tag:theconversation.com,2011:/nz/topics/herd-immunity-1265/articlesHerd immunity – The Conversation2024-03-21T20:24:31Ztag:theconversation.com,2011:article/2262052024-03-21T20:24:31Z2024-03-21T20:24:31ZMeasles is highly contagious, but vaccine-preventable: A primer on recent outbreaks, transmission, symptoms and complications, including ‘immune amnesia’<figure><img src="https://images.theconversation.com/files/583049/original/file-20240320-16-lkngkh.jpg?ixlib=rb-1.1.0&rect=0%2C135%2C3962%2C2913&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A measles virus particle. Measles is one of the most contagious pathogens known.</span> <span class="attribution"><span class="source">(CDC and NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Canada is seeing a resurgence of measles, with cases in the first quarter of 2024 already far surpassing the total for all of 2023. There were <a href="https://www.canada.ca/en/public-health/services/publications/diseases-conditions/measles-rubella-surveillance/2023/week-52.html">12 cases last year</a>, and more than three times that number so far in 2024, with 38 reported as of March 19. </p>
<p>Most of these cases (28) <a href="https://www.quebec.ca/en/health/health-issues/a-z/measles/measles-outbreak">are in Québec</a>, and <a href="https://www.publichealthontario.ca/-/media/Documents/M/24/measles-ontario-epi-summary.pdf?rev=c082f5ae0c6c446f9624d47b7e3c8535&sc_lang=en">eight are in Ontario</a>, while <a href="https://www.saskhealthauthority.ca/news-events/news/measles-exposure-risk-saskatoon">Saskatchewan</a> and <a href="https://news.gov.bc.ca/releases/2024HLTH0026-000274">British Columbia</a> have each reported one case. </p>
<p>As an immunologist with a focus on host-microbe interactions and antiviral immunity, I have been following recent measles outbreaks. </p>
<h2>Symptoms and complications</h2>
<p>Measles (also known as rubeola) is a serious but vaccine-preventable disease caused by an RNA virus of the family <a href="https://www.britannica.com/science/paramyxovirus-virus-family">Paramyxoviridae</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A child seen from behind with a red rash all over his skin" src="https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=720&fit=crop&dpr=1 600w, https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=720&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=720&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=905&fit=crop&dpr=1 754w, https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=905&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/583046/original/file-20240320-24-qx59sq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=905&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Measles rash appears on the face before spreading downward to other areas of the body.</span>
<span class="attribution"><span class="source">(U.S. Centers for Disease Control)</span></span>
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<p>Measles usually begins with fever, runny nose, conjunctivitis (red watery eyes), sore throat and coughing. These can be initially mistaken for common cold or flu.</p>
<p>However, these non-specific signs and symptoms are typically followed by clinical manifestations that are characteristic of measles. These include Koplik spots (tiny white specks with bluish-white centres in the inner lining of the cheeks), and subsequently a <a href="https://www.cdc.gov/measles/symptoms/signs-symptoms.html">measles rash</a> appearing on the face before spreading downward to other areas of the body.</p>
<p>In most cases, measles resolves on its own. However, <a href="https://www.mayoclinic.org/diseases-conditions/measles/symptoms-causes/syc-20374857">severe complications</a> may arise, especially in immunocompromised individuals. <a href="https://www.cdc.gov/globalhealth/measles/about/index.html">Complications</a> can include pneumonia, encephalitis (brain inflammation and swelling), blindness, deafness and permanent neurological consequences. When measles occurs during pregnancy, it can result in miscarriage, premature labour, stillbirth, birth defects or even fetal death. The most severe cases of measles can be fatal. </p>
<p>Also of note, infection with the measles virus can weaken the immune system for months or years, increasing the risk of infections with a wide range of microbes. While measles-associated immunosuppression has been documented for decades, we are only beginning to decipher its underlying mechanisms. For example, a phenomenon called “<a href="https://doi.org/10.1038/s41467-018-07515-0">immune amnesia</a>” is thought to contribute, at least partially, to unrelated infections in the aftermath of measles.</p>
<h2>What is immune amnesia?</h2>
<p>The naturally occurring (wild-type) strains of measles virus can target, infect and kill memory B and T lymphocytes, which are instrumental to antimicrobial defence. This is because one of the three measles virus receptors, called CD150, happens to be abundantly present on the surface of these lymphocytes.</p>
<p>Long-lived memory cells, which accumulate as a result of immunizations and infections over time, remain in a poised state to mount rapid and rigorous recall responses when we re-encounter microbes. B cells orchestrate the production of antibodies that neutralize extracellular microbes, and T cells work to destroy infected cells. Therefore, when people lose their precious memory cells to measles, the immune system is set back to a default mode, as if it has never seen any microbes or vaccines in the past.</p>
<p>To add insult to injury, <a href="https://doi.org/10.1093/infdis/jiaa407">measles virus may also eliminate “memory-like” innate T cells</a>, which also express CD150, thus removing yet another potent weapon from our antimicrobial arsenal. Therefore, collectively, the ability of measles virus to find and kill memory and memory-like lymphocytes can lead to adaptive and <a href="https://doi.org/10.1371/journal.ppat.1009071">innate immune amnesia</a>, rendering a measles patient or survivor prone to many opportunistic infections.</p>
<h2>How does measles spread and how contagious is it?</h2>
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<img alt="microscopic image of a virus" src="https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/583047/original/file-20240320-20-nv4olv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Microscopic view of a measles virus particle (red).</span>
<span class="attribution"><span class="source">(CDC and NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Measles virus spreads easily through airborne droplets released by infected people when they breathe, talk, laugh, cough or sneeze. In addition, measles virus infectious particles can remain active in the air and on contaminated surfaces for up to two hours.</p>
<p>Measles virus is one of the most contagious respiratory pathogens known, with <a href="https://doi.org/10.1016/S1473-3099(17)30307-9">each person with measles passing on their infection to 12 to 18 other people</a> in a susceptible population. Measles virus is more transmissible than influenza viruses and SARS-CoV-2 variants.</p>
<h2>How effective are measles vaccines?</h2>
<p>Measles vaccines are safe, affordable and extremely effective. According to the World Health Organization (WHO), <a href="https://www.who.int/news-room/fact-sheets/detail/measles">measles claimed 2.6 million lives each year before 1963</a> when a measles vaccine became available. Since then, widespread immunization programs have saved millions of lives, including an estimated 56 million just between 2000 and 2021.</p>
<p>Measles vaccines contain a live measles virus strain that has been attenuated so that it does not inflict harm; yet, it is sufficient to generate protective immune responses. </p>
<p>The measles-mumps-rubella (MMR) vaccine or the measles-mumps-rubella-varicella (MMRV) vaccine is routinely administered to children in <a href="https://www.canada.ca/en/public-health/services/diseases/measles/health-professionals-measles.html">two doses</a>, with a first dose being given after the first birthday, typically between 12-15 months of age, followed by a booster dose recommended after 18 months of age and before attending school. This should afford lifelong protection against measles in most people. </p>
<p>According to the United States Centers for Disease Control and Prevention (CDC), one and two doses of the MMR vaccine are <a href="https://www.cdc.gov/vaccines/vpd/mmr/public/index.html">93 per cent and 97 per cent effective</a> in preventing measles, respectively. </p>
<p>Teens and adults should also <a href="https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-12-measles-vaccine.html#">remain up to date with regard to measles immunization</a> since measles can affect anyone. There are blood tests that can be ordered by health-care providers to determine immunity to measles. </p>
<p>The MMR vaccine can be <a href="https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-12-measles-vaccine.html#">given at any time</a> during one’s lifespan, but the MMRV vaccine is authorized in Canada only between one and 13 years of age.</p>
<h2>Why are measles cases returning?</h2>
<p>Recent years have witnessed a rise in measles outbreaks within and outside Canada. This is primarily due to an alarming decline in measles vaccination caused by <a href="https://theconversation.com/measles-global-increase-in-cases-likely-driven-by-covid-pandemic-182250">delayed childhood immunizations amid COVID-19</a> lockdowns, vaccine hesitancy <a href="https://theconversation.com/measles-outbreak-why-are-anti-vaxxers-risking-a-public-health-crisis-116334">creating vulnerable societal pockets</a>, anti-vaccine sentiments and <a href="https://time.com/6564694/measles-antivaccine-misinformation/">digital misinformation</a> spread through online social media, and the resumption of global travel post-COVID.</p>
<p>Measles outbreaks occur soon after <a href="https://doi.org/10.1001/jama.2020.20895">herd immunity</a> is compromised. Herd immunity is achieved when an adequately large proportion of a population becomes immune to a specific pathogen through prior infections or vaccination. As a result, the probability of an infectious case encountering a susceptible person drops dramatically. </p>
<p>For measles, the necessary <a href="https://www.who.int/news/item/23-11-2022-nearly-40-million-children-are-dangerously-susceptible-to-growing-measles-threat">threshold for herd immunity is 95 per cent</a>. This means when 95 per cent of people in a population are immune, the remaining five per cent (including newborns, unvaccinated or undervaccinated children and immunodeficient people who cannot receive a measles vaccine) are also indirectly protected since the risk of measles virus transmission is significantly minimized.</p>
<p>By receiving two doses of a measles vaccine, one protects not only themselves but also the vulnerable members of their community. The only way to avoid measles and its serious complications, including proneness to a broad spectrum of unrelated infections, is to vaccinate widely, to engage those who are hesitant to have their children immunized in a respectful dialogue, and to educate the public regarding the unparalleled benefits of measles vaccines.</p>
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Read more:
<a href="https://theconversation.com/how-better-conversations-can-help-reduce-vaccine-hesitancy-for-covid-19-and-other-shots-159321">How better conversations can help reduce vaccine hesitancy for COVID-19 and other shots</a>
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<p>It is also crucial to isolate infected individuals for four days after the appearance of a measles rash to prevent measles virus transmission to others.</p>
<p>In Canada, measles has been <a href="https://www.canada.ca/en/public-health/services/diseases/measles/surveillance-measles.html">a nationally notifiable disease</a> since 1924 (except between 1959 and 1968), and the Canadian Measles and Rubella Surveillance System (CMRSS) ensures the weekly collection of measles data from every province and territory, including zero report submissions.</p><img src="https://counter.theconversation.com/content/226205/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mansour Haeryfar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Canada is seeing a surge in measles cases. Find out what measles is, why it’s returning to Canada, and how people can protect themselves and others.Mansour Haeryfar, Professor of Immunology, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2195182023-12-11T12:37:21Z2023-12-11T12:37:21ZWhooping cough cases increasing in the UK – what you need to know<figure><img src="https://images.theconversation.com/files/564677/original/file-20231210-29-ny65no.jpg?ixlib=rb-1.1.0&rect=35%2C0%2C7904%2C5297&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/child-got-sick-virus-little-boy-1693664527">Zdan Ivan/Shutterstock</a></span></figcaption></figure><p>You may have read recent alarming reports of a cough that “<a href="https://www.thesun.co.uk/health/24974770/highly-contagious-cough-fractured-ribs-whooping-cough/">lasts 100 days</a>” is “<a href="https://www.mirror.co.uk/news/health/100-day-cough-quickly-spreading-31622932">quickly spreading across the UK</a>” and can “<a href="https://nypost.com/2023/12/07/lifestyle/100-day-cough-highly-contagious-infection-that-could-fracture-ribs-soars-250-in-uk/">fracture ribs</a>”. If you didn’t look beyond the headlines, you might have missed the fact that the reports are about <a href="https://www.nhs.uk/conditions/whooping-cough/">whooping cough</a>.</p>
<p>So, what is going on?</p>
<p>Whooping cough (or pertussis) is what is known in the UK as a “notifiable infectious disease”, which means any doctor who diagnoses a case has a legal duty to report the infection to the local authority. Notifications of whooping cough are indeed much higher this year, particularly in the five months since July than at any time during the previous three years. </p>
<p>In the 21 weeks to November 27, <a href="https://www.gov.uk/government/publications/notifiable-diseases-weekly-reports-for-2023">there were 716 notifications</a> compared with just 217 in the same period in 2022, 213 in 2021 and just 72 in 2020. That is more than a threefold rise this year compared with the previous year. </p>
<p>Like most respiratory infections, whooping cough was suppressed during the COVID years. Notifications for whooping cough this year are still <a href="https://www.gov.uk/government/publications/notifiable-diseases-weekly-reports-for-2023">markedly down on 2019</a> where there were 1,842 notifications over the same 21-week period. </p>
<p>What we are seeing now is a partial return to the pre-COVID situation and not an unprecedented surge in infections. (Although the reported cases represent only a <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-14-147">fraction of all cases</a> in the community.)</p>
<p>The fact that whooping cough notifications are still relatively low should not distract from the fact that infections in the 2010s were still much <a href="https://www.gov.uk/government/publications/notifiable-diseases-historic-annual-totals">higher than in the previous decade</a>. Since the mid-1950s and the introduction of a vaccine, whooping cough was <a href="https://www.gov.uk/government/publications/pertussis-the-green-book-chapter-24">generally in decline</a> until this most recent decade. </p>
<h2>What is whooping cough?</h2>
<p>Whooping cough is a chest infection caused by the bacterium <em>Bordetella pertussis</em> – although another bacterium <em>Bordetella parapertussis</em> can also cause it. </p>
<p>The illness lasts for about six weeks or more and <a href="https://emedicine.medscape.com/article/967268-overview">progresses through three stages</a>. The first stage is very similar to a bad cold with a runny nose, sneezing and sore eyes. </p>
<p>The second phase, which starts after about two weeks, is characterised by bouts of intense coughing. Each bout can last several minutes and is occasionally followed by the loud whoop that gives the disease its name. Afterwards, a chronic cough can remain for several weeks.</p>
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<figcaption><span class="caption">What whooping cough sounds like.</span></figcaption>
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<p>Most people eventually make a full recovery, but in babies under three months old <a href="https://emedicine.medscape.com/article/967268-overview#a6">1% to 3% may die</a>. And most children under six months will require hospitalisation. </p>
<p>About one in 50 babies under one year will <a href="https://www.cdc.gov/pertussis/about/complications.html">suffer convulsions</a> and one in 150 (0.6%) will have encephalopathy (swelling of the brain). </p>
<p>Other even more serious neurological problems, such as paralysis and blindness, have been reported but are rare. In older children and adults, fainting, rib fractures, <a href="https://www.cdc.gov/pertussis/about/complications.html">pneumonia and urinary incontinence</a> can occur. </p>
<p>Antibiotics have limited value in <a href="https://onlinelibrary.wiley.com/doi/10.1002/ebch.1845">treating whooping cough</a>. They can reduce the time that the patient is infectious to others, but they have limited effect on preventing symptoms. </p>
<h2>How to avoid getting it</h2>
<p>There is an effective vaccine for whooping cough that in the UK is given in <a href="https://www.gov.uk/government/publications/routine-childhood-immunisation-schedule/routine-childhood-immunisations-from-february-2022-born-on-or-after-1-january-2020">combination with other vaccines</a> at eight, 12 and 16 weeks old. Then there is a booster shot given when the child is three years and four months. </p>
<p>The vaccine is also now recommended for pregnant women. This is not to protect the mother but to protect their baby during the first weeks of the child’s life before the first course of vaccine – when the infant would be at the highest risk of death.</p>
<p>Concerns about the safety of the vaccine, particularly during the 1970s, led to a significant fall in vaccine coverage and a re-emergence of whooping cough. </p>
<p>A committee of the US Institute of Medicine concluded that the evidence was “<a href="https://www.ncbi.nlm.nih.gov/books/NBK234367/">consistent with a causal relationship</a>” between the vaccine and acute encephalopathy, with a risk estimated at between zero and ten cases per million jabs administered. </p>
<p>However, subsequent studies suggested that many of the cases in the biggest study had a particular <a href="https://pubmed.ncbi.nlm.nih.gov/20447868/">genetic abnormality known as Dravet syndrome</a> and the whooping cough vaccine was merely bringing forward the date of onset of problems that would have happened anyway. </p>
<p>In any event, the studies reported above were of a time when whole-cell vaccines were being used (made from killed whole bacteria). Since 2004, whooping cough vaccines made with just parts of the bacterium (so-called acellular vaccine) have been used in the UK and these are associated with a <a href="https://pubmed.ncbi.nlm.nih.gov/12706690/">lower risk of side-effects</a>.</p>
<h2>Far from clear</h2>
<p>The recent increase in notifications of whooping cough, as mentioned above, is due to COVID suppression measures – lockdowns, mask-wearing and hand hygiene – coming to an end. But why there were more whooping cough cases during the years 2010 to 2019 compared with the previous decade is far from clear. </p>
<p>Vaccine coverage in the years before COVID up to 2019 was <a href="https://www.gov.uk/government/publications/pertussis-the-green-book-chapter-24">no lower than ten years previously</a>. <a href="https://karger.com/mpp/article/31/4/313/825084/Whole-Cell-and-Acellular-Pertussis-Vaccine">Possible explanations</a> include waning immunity, greater awareness of whooping cough among doctors (so more diagnoses), and improved laboratory diagnosis. </p>
<p>My take on the evidence is that the increasing infections in the years before COVID was down to the shift from whole-cell to acellular vaccine. Although the acellular vaccines cause fewer side-effects, they also generate <a href="https://karger.com/mpp/article/31/4/313/825084/Whole-Cell-and-Acellular-Pertussis-Vaccine">less powerful immunity</a>.</p>
<p>While both vaccines are highly effective at preventing severe disease, the acellular vaccine does not prevent mild infections that can be <a href="https://karger.com/mpp/article/31/4/313/825084/Whole-Cell-and-Acellular-Pertussis-Vaccine">infectious for others for as long</a>, so allowing the infection to continue to spread in the community. </p>
<p>The whole-cell pertussis vaccines were able to achieve herd immunity, which the acellular ones probably cannot. So the chance that young babies come into contact with an infectious older child or adult is now greater. </p>
<p>With the falling vaccination coverage in <a href="https://www.gov.uk/government/publications/pertussis-immunisation-in-pregnancy-vaccine-coverage-estimates-in-england-october-2013-to-march-2014/pertussis-vaccination-coverage-for-pregnant-women-in-england-january-to-march-and-annual-coverage-2021-to-2022">pregnant women</a> this puts babies at risk in their most vulnerable first weeks of life.</p><img src="https://counter.theconversation.com/content/219518/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Hunter consults for the World Health Organization. He receives funding from National Institute for Health Research and has received funding from the World Health Organization and the European Regional Development Fund.</span></em></p>Antibiotics aren’t very effective against it, but we do have a vaccine.Paul Hunter, Professor of Medicine, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2102332023-07-27T14:46:30Z2023-07-27T14:46:30ZMeasles: it’s not just London that’s at risk of an outbreak – it’s all of the UK<p>Since the start of 2023, measles has been reported in a third of countries in the World Health Organization (WHO) European region. And in the first five months of the year, there were <a href="https://www.who.int/europe/news/item/19-07-2023-european-region-achieves-high-routine-immunization-coverage--but-falls-short-of-pre-pandemic-levels">5,699 cases reported there</a> – nearly seven times as many as in the whole of 2022. </p>
<p>The UK lost its measles-free status in 2019, indicating that the measles virus was circulating and there was inadequate vaccination to prevent its spread. If exposed to the measles virus, <a href="https://www.who.int/news-room/fact-sheets/detail/measles#:%7E:text=Transmission,of%20their%20unvaccinated%20close%20contacts.">90% of unvaccinated people will get infected</a>. The virus spreads like wildfire among the unvaccinated, as demonstrated recently when seven unvaccinated children at a nursery school in <a href="https://www.bbc.co.uk/news/uk-england-stoke-staffordshire-66297202">Stoke-on-Trent nursery</a> caught the bug.</p>
<p>With the <a href="https://www.gov.uk/government/publications/health-protection-report-volume-17-2023/hpr-volume-17-issue-7-news-14-july-2023">latest data</a> from the UK Health Security Agency (UKHSA) showing at least one measles case in each region in England this year, and warnings of the potential for outbreaks in London, where else in the UK are children at risk? The short answer is probably “everywhere”. </p>
<p>Schools in all four devolved nations have now broken up for the summer holidays and people are travelling both in the UK and abroad and may encounter the measles virus on their travels. Eighty-one per cent of the 128 confirmed cases of measles in England so far in 2023 have been as a result of in-country community transmission.</p>
<p>There are no specific drugs for measles, so treatment is to help relieve symptoms and address complications, such as bacterial infections. <a href="https://www.cdc.gov/globalhealth/newsroom/topics/measles/index.html">For every 1,000 people infected</a>, between one and three of them will die (deaths are highest in children under the age of five and those with weakened immune systems). </p>
<p>Deaths are commonly due to secondary bacterial infections. Pneumonia accounts for 60% of measles-associated deaths.</p>
<p>Other complications such as deafness, fits and encephalitis (brain inflammation) are relatively common. Around 25% of people who develop measles need hospital care.</p>
<p>But measles is a highly preventable disease, with two doses of the measles, mumps and rubella (MMR) vaccine <a href="https://www.nhs.uk/conditions/vaccinations/mmr-vaccine/">protecting around 97%</a> of people. In the UK, MMR is given as part of the <a href="https://www.nhs.uk/conditions/vaccinations/nhs-vaccinations-and-when-to-have-them/">routine childhood immunisation schedule</a>, with dose one (MMR1) given around the age of 12 months, and MMR2 given as part of the pre-school boosters at age three years and four months. </p>
<p>Yet MMR levels across many parts of the UK fall far short of the 95% coverage needed for <a href="https://theconversation.com/measles-how-declining-vaccination-levels-in-london-are-threatening-herd-immunity-209827">“herd immunity” against measles</a> – where enough people are vaccinated that the virus is unable to spread. In the first quarter of 2023, UK-wide coverage for <a href="https://www.gov.uk/government/statistics/cover-of-vaccination-evaluated-rapidly-cover-programme-2022-to-2023-quarterly-data">MMR2 by the age of five</a> (that is, more than 18 months after it’s due) was just below 86% and no devolved nation had coverage above 90%. </p>
<p>While London has the lowest coverage for the same metric (at around 75%), only one of the other six NHS England regions had coverage above 90% (and even then, only just, at 90.5%).</p>
<p>There have always been pockets of populations with much lower-than-average levels of MMR coverage, but this has become much more complicated during the pandemic when disruptions to services in early waves meant that certain age groups may also have missed out on routine childhood immunisations. </p>
<p>For example, of the children attending a large paediatric emergency department in Greater Manchester, it was found that <a href="https://bmjopen.bmj.com/content/13/6/e072053">just 20%</a> of four-year-olds had received both the required doses of MMR. This pattern is seen globally, with many countries yet to attain the levels of routine immunisation coverage they had pre-pandemic. During 2022, <a href="https://www.who.int/news-room/fact-sheets/detail/immunization-coverage">21.9 million children missed</a> their first dose of a measles vaccine – nearly 3 million more than in 2019.</p>
<p>Mumps and rubella – viruses also covered by the MMR vaccine – are also highly infectious diseases and can make children extremely ill. Complications include deafness and fits. But it’s never too late to catch up on a missed dose of the MMR vaccine. </p>
<p>In the UK, you can check your vaccinations with your GP surgery. There are <a href="https://www.nhs.uk/conditions/vaccinations/mmr-vaccine/">some situations</a> where older children and adults need to check they are up to date with their vaccinations, for example, if they are about to start university or travel abroad. </p>
<p>Adults in different age groups might also not be fully protected – for example, those who have been immunised according to the NHS schedule and were born between 1970 and 1979 may only be vaccinated against measles. And those born between 1980 and 1990 may not be protected against mumps.</p>
<p>But measles isn’t the only vaccine-preventable disease on the rise. Last year’s discovery of type 2 <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(22)01804-9/fulltext">polio virus</a> in London wastewater and reports of increased cases of <a href="https://www.gov.uk/government/publications/diphtheria-cases-among-asylum-seekers-in-england-2022/diphtheria-cases-among-asylum-seekers-in-england-2022">diphtheria</a> among a vulnerable population in England means that improving routine childhood vaccination coverage should be a priority. </p>
<p>For MMR, a national catch-up campaign is underway, and many regions have set up measles-elimination groups. If this work is successful, hopefully the UK will be able to regain its measles-free status.</p><img src="https://counter.theconversation.com/content/210233/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Professor Rachel Isba receives funding from Action Medical Research (AMR) and the National Institute for Health and Care Research (NIHR) and has previously received funding from the Children's Hospital Alliance (CHA), Health Education England (HEE), the Sir Halley Stewart Trust, and the Dowager Countess Eleanor Peel Trust. She is a Trustee of the Royal Society for Public Health. </span></em></p>Seven children at a nursery in Stoke-on-Trent have caught measles. But other parts of the UK are at risk too.Rachel Isba, Professor of Medicine, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2098272023-07-18T16:10:33Z2023-07-18T16:10:33ZMeasles: how declining vaccination levels in London are threatening herd immunity<figure><img src="https://images.theconversation.com/files/538068/original/file-20230718-23-6nl8w9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5176%2C3445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/viral-disease-rash-measles-concept-doctor-1297395328">fotohay/Shutterstock</a></span></figcaption></figure><p>The UK Health Security Agency (UKHSA) <a href="https://www.gov.uk/government/publications/health-protection-report-volume-17-2023/hpr-volume-17-issue-7-news-14-july-2023">has warned</a> of an increased risk of measles outbreaks, particularly in London. </p>
<p>Although the probability of a large epidemic is still considered to be low elsewhere in the UK, the UKHSA’s projections suggest the capital could see <a href="https://www.gov.uk/government/publications/measles-risk-assessment-for-resurgence-in-the-uk">40,000 to 160,000 cases</a>, with hospitalisation rates of 20%-40%.</p>
<p>For 60 years, measles has been preventable by a <a href="https://www.nhs.uk/conditions/vaccinations/mmr-vaccine/">widely available vaccine</a>, so why is London facing a potential disaster now? </p>
<p>The answer lies in faltering vaccine coverage, particularly since the late 1990s, but <a href="https://theconversation.com/measles-global-increase-in-cases-likely-driven-by-covid-pandemic-182250">exacerbated</a> by COVID pandemic. </p>
<p>Measles is a viral infection that primarily affects children but can also occur in adults. It can cause <a href="https://academic.oup.com/jid/article/189/Supplement_1/S4/823958">serious complications</a>, particularly in people with weakened immune systems. </p>
<p>The measles virus <a href="https://www.who.int/news-room/fact-sheets/detail/measles">spreads</a> through respiratory droplets from an infected person, making it easily transmissible in close quarters such as schools, hospitals, and public transport. It’s known to be one of the most infectious pathogens affecting humans. </p>
<p>The <a href="https://theconversation.com/coronavirus-is-the-r-number-still-useful-138542">basic reproduction number</a>, R, for measles, is estimated to be <a href="https://pubmed.ncbi.nlm.nih.gov/28757186/">between 12 and 18</a>. This means one infected child can pass on the disease to 12 to 18 other children in a completely susceptible population. </p>
<p>The effective reproduction number, Re, takes into account the proportion of contacts who are not susceptible, either because they have already had measles or have been vaccinated. If the Re is larger than one, the disease spreads. </p>
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Read more:
<a href="https://theconversation.com/vaccine-hesitancy-is-one-of-the-greatest-threats-to-global-health-and-the-pandemic-has-made-it-worse-208227">Vaccine hesitancy is one of the greatest threats to global health – and the pandemic has made it worse</a>
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<p>Before measles vaccines became available, almost everybody over five would have had the disease, which for most meant lifelong immunity. But <a href="https://academic.oup.com/jid/article/189/Supplement_1/S4/823958?login=false">complications</a> like encephalitis or pneumonia caused many <a href="https://en.wikipedia.org/wiki/Olivia_Dahl">deaths</a>. Even today, thousands die <a href="https://www.who.int/news-room/fact-sheets/detail/measles">from measles</a> globally every year – mostly unvaccinated young children.</p>
<p>Vaccination campaigns have been <a href="https://ourworldindata.org/vaccination#how-vaccines-work-herd-immunity">remarkably successful</a> in reducing the number of measles cases. Mass vaccination programmes started in the 1960s and quickly suppressed the spread in most developed countries. The measles shot is a “<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9595357/">sterilising</a>” vaccine, which means it not only prevents illness, but also transmission.</p>
<p><strong>Measles cases in the US, 1938–2019</strong></p>
<figure class="align-center ">
<img alt="A graph showing how vaccinations in the US affected measles cases." src="https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=356&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=356&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=356&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=448&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=448&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538009/original/file-20230718-25-c5oh3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=448&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/3/3f/Measles_US_1938-2019.png">Julius Senegal</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>We don’t actually need to vaccinate every single person against measles for everybody to be protected. By vaccinating a large enough proportion of the population, we can lower the Re below one, effectively “starving” the pathogen of new hosts. The population then reaches “<a href="https://theconversation.com/herd-immunity-why-the-figure-is-always-a-bit-vague-141839">herd immunity</a>”.</p>
<p>Mathematical modelling, taking in the virus’ reproduction number and other factors, allows us <a href="https://theconversation.com/what-is-herd-immunity-and-how-many-people-need-to-be-vaccinated-to-protect-a-community-116355">to estimate</a> the level of vaccination needed to reach and maintain herd immunity. </p>
<p>For measles to be eliminated, <a href="https://www.nhs.uk/conditions/vaccinations/why-vaccination-is-safe-and-important/">between 90% and 95%</a> of the population <a href="https://www.who.int/news/item/10-11-2021-global-progress-against-measles-threatened-amidst-covid-19-pandemic">should be immune</a> (either from vaccination or infection).</p>
<p>Herd immunity could be lost if we don’t keep vaccinating children who are born susceptible to measles. Two doses of the measles, mumps and rubella (MMR) vaccine are <a href="https://www.cdc.gov/vaccines/vpd/measles/index.html">needed</a> – the first at 12 months and the second at age five – for effective protection.</p>
<p>The current levels of MMR coverage in England, particularly in London, are <a href="https://www.gov.uk/government/news/london-at-risk-of-measles-outbreaks-with-modelling-estimating-tens-of-thousands-of-cases">well below</a> the 95% threshold. </p>
<p><strong>Vaccination levels needed to maintain herd immunity</strong></p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=496&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=496&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=496&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=623&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=623&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537912/original/file-20230717-27-pnlijj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=623&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This graph shows vaccination levels needed for herd immunity for diseases with different R values, and how this applies to measles.</span>
<span class="attribution"><a class="source" href="https://www.gov.uk/government/publications/measles-risk-assessment-for-resurgence-in-the-uk">UKHSA; Adam Kleczkowski</a>, <span class="license">Author provided</span></span>
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<p><strong>MMR vaccination levels across different age groups in London</strong></p>
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<img alt="This graph shows vaccination levels for MMR 1 and MMR 2 across different age groups in London for children born between 1985 and 2016." src="https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=583&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=583&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=583&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=733&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=733&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538040/original/file-20230718-26248-b0ibpg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=733&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="source" href="https://www.gov.uk/government/publications/measles-risk-assessment-for-resurgence-in-the-uk">UKHSA; Adam Kleczkowski</a>, <span class="license">Author provided</span></span>
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<p>The UK has never reached the 95% level of MMR coverage recommended by the World Health Organization (WHO) to eliminate measles, although it has come close enough to prevent a repeat of the large outbreaks that regularly occurred before the 1960s. </p>
<p>However, a drop in vaccination rates in the late 1990s meant <a href="https://theconversation.com/measles-epidemic-parents-reluctant-to-vaccinate-their-children-need-to-hear-of-the-horrors-of-forgotten-diseases-122688">repeated revivals</a> of the virus. This drop is often <a href="https://www.bbc.co.uk/programmes/w3cswjk9">linked</a> to the publication of Andrew Wakefield’s Lancet paper linking the MMR vaccine to autism, which has since been debunked.</p>
<p>Then, in 2017, the WHO declared that the UK had <a href="https://ukhsa.blog.gov.uk/2019/08/19/measles-in-england/">eliminated measles</a>, but this was not maintained. Cases subsequently started occurring more frequently in areas with particularly low vaccination coverage. An <a href="https://www.gov.uk/government/news/measles-outbreaks-across-england">outbreak in England</a> between 2017 and 2018 saw a nearly fourfold increase in confirmed cases. Other <a href="https://www.bbc.com/news/health-45246049">European countries</a> had similar problems.</p>
<p>The COVID pandemic has seen vaccination levels drop further, creating a <a href="https://www.who.int/news/item/27-04-2022-unicef-and-who-warn-of--perfect-storm--of-conditions-for-measles-outbreaks--affecting-children">perfect storm</a> of <a href="https://www.gov.uk/government/publications/measles-risk-assessment-for-resurgence-in-the-uk">low immunity levels</a>. </p>
<p>Some children born since 2015 who were going to be given their second MMR shot during the COVID pandemic missed it. These groups of children are at particular risk, as they are now at school, where they can easily catch the virus. </p>
<p>As well as COVID lockdowns limiting access to routine healthcare, vaccine hesitancy and <a href="https://bylinetimes.com/2021/10/01/inside-the-radicalised-anti-vaxxer-network-influencing-government-vaccine-advisory-panel/?s=09">outright anti-vaxxer attitudes</a> have likely been magnified by COVID <a href="https://www.bbc.com/news/54893437">vaccine misinformation</a>. </p>
<p><strong>Estimated immunity levels for different age groups, London and England</strong></p>
<figure class="align-center ">
<img alt="This graph shows the estimated immunity levels for different age groups in London and England for children born between 1985 and 2016." src="https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=599&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=599&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=599&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=752&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=752&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538031/original/file-20230718-21-vbdwkp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=752&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="source" href="https://www.gov.uk/government/publications/measles-risk-assessment-for-resurgence-in-the-uk">UKHSA; Adam Kleczkowski</a>, <span class="license">Author provided</span></span>
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<p>While only <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1170146/risk-assessment-for-measles-resurgence-in-the-UK-2023.pdf">three-quarters</a> of eligible five-year-olds in London have received their second MMR dose, immunity levels are not the same across all age groups. The UKHSA has sought to work out immunity levels in different age groups to better understand the risk of outbreaks. </p>
<p>The UKHSA <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/769970/UK_measles_and_rubella_elimination_strategy.pdf">combined</a> the proportion of vaccinated people in different age groups with vaccine <a href="https://www.cdc.gov/vaccines/vpd/measles/index.html">efficacy</a> (93% after the first dose and 97% after two). It also accounted for the misclassification of unvaccinated and under-vaccinated people. </p>
<p>The resulting immunity levels are unevenly distributed across ages, as seen in the graph above. Most adults 55 or over are likely to have had measles when they were young. Children born between the start of the vaccination programme and the late 1980s were given a catch-up in 1994 and 1996 and are relatively safe. But children born in the late 1990s and early 2000s are potentially at high risk, as is the most recent, post-2015 cohort. </p>
<p>With its consistently low vaccination levels, London is more likely to face an outbreak than the rest of the UK. Counting how many people would need to become infected to fill in the “immunity gap” gives the worst-case estimate of 160,000 cases for the capital.</p>
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Read more:
<a href="https://theconversation.com/measles-outbreaks-and-political-crises-go-hand-in-hand-122968">Measles outbreaks and political crises go hand in hand</a>
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<p>Some <a href="https://www.gov.uk/government/collections/notifications-of-infectious-diseases-noids">1,053 cases</a> of measles were reported in England and Wales over the past year, and we could see more. Most of the new disease outbreaks can <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/849538/PHE_Measles_Guidelines.pdf">be controlled</a> by emergency vaccination and management of contacts. But loss of immunity makes the virus escape more likely and could lead to large, uncontrollable outbreaks.</p><img src="https://counter.theconversation.com/content/209827/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Kleczkowski receives funding from the UKRI and from the Scottish Government. He is a trustee of the Scottish Forestry Trust.</span></em></p>Projections from the UKHSA suggest London could see a measles outbreak totalling 40,000 to 160,000 cases at current vaccination levels.Adam Kleczkowski, Professor of Mathematics and Statistics, University of Strathclyde Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1974542023-01-23T12:26:19Z2023-01-23T12:26:19ZCOVID is running rampant in China – but herd immunity remains elusive<p>After nearly three years of keeping COVID under control, China is experiencing a massive new wave of COVID infections. The official figures reporting <a href="https://apnews.com/article/health-china-beijing-covid-425a5de577126b042d4eea915c174bc0">60,000 deaths</a> between <a href="https://edition.cnn.com/2023/01/14/china/china-covid-deaths-intl/index.html">December 8 and January 12</a> are widely seen as underestimating the impact of the outbreak.</p>
<p>Until December 2022, China had used <a href="https://www.nature.com/articles/d41586-022-04382-0">lockdown policies</a> to reduce the opportunity for COVID spread in the hope of eliminating the virus or building up enough population immunity through vaccination. The exceptionally strict zero-COVID policy was very successful in stopping the virus’ spread while the world faced returning deadly waves. </p>
<p>However, the <a href="https://www.bloomberg.com/opinion/articles/2023-01-03/china-herd-immunity-people-are-so-sick-of-covid-zero-they-just-want-to-get-sick">prolonged lockdowns</a> eventually became politically and economically unsustainable. China’s <a href="http://www.nhc.gov.cn/xcs/s3574/202301/a68301ee500b436b989ec5be2a35cad2.shtml">official policy</a> is currently concentrating on strengthening the early detection and treatment of severe cases rather than the prevention of infections. This has led to claims the country is now pursuing a “<a href="https://www.theepochtimes.com/xi-lying-flat-and-losing-out-no-way-even-purged-opponents-rally-around-him-as-the-west-gets-it-wrong-again_4982775.html">herd immunity</a>” approach.</p>
<p>But would this be a realistic goal? Lessons from other countries’ experiences suggest not. Let’s take a look at why. </p>
<h2>Herd immunity: a recap</h2>
<p>The <a href="https://theconversation.com/herd-immunity-why-the-figure-is-always-a-bit-vague-141839">herd immunity</a> concept was <a href="https://www.cambridge.org/core/journals/epidemiology-and-infection/article/spread-of-bacterial-infection-the-problem-of-herdimmunity/FAFA36F92CEA92AC1FA6C942B37568D9">introduced</a> some 100 years ago to explain why epidemic waves often stop before affecting the whole population. </p>
<p>As a disease such as COVID spreads, more people become infected. Most of them recover and gain infection-induced immunity. Those who become infected increasingly have contact with immune rather than susceptible people. This leads to lower risk of passing on the infection.</p>
<p>The epidemic wave slows down and eventually declines. The decline is caused by a sufficiently large number of people becoming immune, therefore protecting the whole population – or the “herd”. In the 1970s, epidemiologists found a <a href="https://academic.oup.com/cid/article/52/7/911/299077">simple formula</a> that predicts the proportion of immune individuals at which the number of infections stops growing.</p>
<p>The formula includes the <a href="https://www.gov.uk/guidance/the-r-value-and-growth-rate#:%7E:text=The%20reproduction%20number%20(%20R%20)%20is,number%20of%20infections%20is%20stable.">R number</a>, the average number of people one infected person passes the disease onto. Non-pharmaceutical interventions, like social distancing, lockdowns, or mask-wearing, are aimed at reducing the transmissibility of the virus, lowering the value of R. </p>
<figure class="align-center ">
<img alt="A man wearing full PPE in Shanghai, May 2022." src="https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505093/original/file-20230118-7953-54i5t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">China’s COVID zero strategy proved unsustainable.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/shanghai-china-may-10-2022-enters-2154392867">Graeme Kennedy/Shutterstock</a></span>
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</figure>
<p>The herd immunity threshold also depends on the proportion of people with <a href="https://www.nature.com/articles/s41541-022-00594-7">pre-existing immunity</a> from either previous outbreaks or vaccination. Using these concepts, scientists have designed vaccination strategies that successfully keep contagious diseases such as smallpox, polio, diphtheria and rubella under control.</p>
<p>For such public health policies to be successful, mass vaccination needs to reach a high proportion of the population. Sublineages of <a href="https://theconversation.com/new-covid-variants-may-be-more-transmissible-but-that-doesnt-mean-the-r0-or-basic-reproduction-number-has-increased-186826">the omicron variant BA.5</a> are currently <a href="https://www.who.int/news/item/04-01-2023-tag-ve-statement-on-the-3rd-january-meeting-on-the-covid-19-situation-in-china">dominant in China</a>. Omicron has <a href="https://academic.oup.com/jtm/article/29/3/taac037/6545354">an average R of 9.5</a>, so around 90% of the population needs to be fully protected to reach herd immunity, according to <a href="https://academic.oup.com/cid/article/52/7/911/299077">the model</a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/herd-immunity-why-the-figure-is-always-a-bit-vague-141839">Herd immunity: why the figure is always a bit vague</a>
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<p>However, vaccination is not perfect. Some 89% of China’s population has so far <a href="https://en.wikipedia.org/wiki/COVID-19_vaccination_in_mainland_China">reportedly received</a> two doses of the vaccine. But booster uptake <a href="https://www.cnbc.com/2022/11/29/china-says-covid-vaccination-rates-for-seniors-has-climbed-over-the-last-two-weeks.html">is low</a> and the efficacy of the <a href="https://www.who.int/news-room/feature-stories/detail/the-sinovac-covid-19-vaccine-what-you-need-to-know">Sinovac</a> and <a href="https://www.who.int/news-room/feature-stories/detail/the-sinopharm-covid-19-vaccine-what-you-need-to-know">Sinopharm</a> vaccines used in China <a href="https://cdn.who.int/media/docs/default-source/immunization/sage/2021/april/5_sage29apr2021_critical-evidence_sinovac.pdf">is lower</a> than the mRNA vaccines from Pfizer and Moderna used widely. So, the actual percentage of people protected by the vaccine <a href="https://www.forbes.com/sites/georgecalhoun/2022/12/31/the-impact-of-chinas-zero-covid-exit-is-china-really-vaccinated/">will be lower</a> than in other countries – perhaps <a href="https://www.airfinity.com/articles/china-risks-between-1-3-and-2-1-million-deaths-if-it-ends-its-zero-covid">as low as 5%</a>.</p>
<p>Before December 2022, China had seen relatively few COVID cases, leaving infection-induced immunity low. This creates a significant gap between the existing levels of immunity and those required to achieve herd immunity, as illustrated in the figure below. In the absence of other control measures, this gap will need to be filled in by infection, resulting in a massive outbreak.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=519&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=519&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=519&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=652&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=652&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505154/original/file-20230118-19-qyhb3p.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=652&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The 5% vaccination-induced immunity level, shown here for illustration purposes, reflects the limited booster coverage and the lower efficacy and faster waning of China’s vaccines.</span>
<span class="attribution"><span class="source">Adam Kleczkowski</span></span>
</figcaption>
</figure>
<h2>Predictions are challenging</h2>
<p>Predicting what will happen next in China <a href="https://edition.cnn.com/2023/01/05/china/china-covid-outbreak-who-data-intl-hnk/index.html">is difficult</a> due to the lack of reliable data. Although cases now seem to be decreasing, the traditional activity around the <a href="https://www.washingtonpost.com/world/2023/01/11/china-covid-cases-lunar-new-year/">lunar new year</a> will most likely cause a new wave.</p>
<p>Several models have explored different assumptions. The Institute for Health Metrics and Evaluation <a href="https://covid19.healthdata.org/china?view=cumulative-deaths">expects</a> almost three million cases per day at an upcoming peak following the lunar new year and 1.6 million <a href="https://www.nature.com/articles/d41586-022-04502-w">deaths</a> by the end of 2023.</p>
<figure class="align-center ">
<img alt="A model showing three scenarios for the trajectory of COVID cases in China." src="https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=521&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=521&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=521&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=655&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=655&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505169/original/file-20230118-24-cqgmhg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=655&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><span class="source">Institute for Health Metrics and Evaluation, University of Washington and Adam Kleczkowski</span></span>
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<p>Health data analytics company Airfinity <a href="https://www.airfinity.com/articles/chinas-covid-19-wave-forecast-to-have-two-peaks-where-cases-could-reach-4-2">predicts</a> four million cases per day at the peak of the upcoming wave, and that the number of deaths could reach <a href="https://www.airfinity.com/articles/china-risks-between-1-3-and-2-1-million-deaths-if-it-ends-its-zero-covid">2.1 million</a>. Given the uncertainty about the epidemic spread in China, these numbers might even be underestimates.</p>
<p>Eventually, China’s population will <a href="https://www.bbc.co.uk/news/world-asia-china-64208127">temporarily reach</a> the “herd immunity” level, and the upcoming wave will probably peak around March 2023, according to these models. But this is not a guarantee that the epidemic will end there. </p>
<p>The virus persists even in countries like the UK, where <a href="https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/articles/coronaviruscovid19latestinsights/antibodies">roughly 80%–95% of the population</a> have COVID antibodies. This indicates high levels of immunity from prior infection, vaccination, or both. </p>
<p>Unfortunately, the <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(22)00833-7/fulltext">immunity</a> from COVID vaccines and prior infections <a href="https://www.reuters.com/business/healthcare-pharmaceuticals/antibodies-sinovacs-covid-19-shot-fade-after-about-6-months-booster-helps-study-2021-07-26/">wanes after some months</a> and may be less durable against new variants. As a result, new waves appear as herd immunity is temporarily breached, before being restored again. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/chinas-covid-situation-is-dire-but-it-shouldnt-pose-a-big-risk-to-other-countries-197219">China's COVID situation is dire – but it shouldn't pose a big risk to other countries</a>
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<p>If China is really aiming at herd immunity to eliminate the virus – and some young Chinese people are apparently <a href="https://www.bbc.co.uk/news/world-asia-china-64183281">seeking infection</a> – it will very likely <a href="https://www.nature.com/articles/d41586-021-00728-2">fail again</a>. The repeated lesson from other countries is that the loss of immunity and the appearance of new variants make herd immunity a futile goal when it comes to COVID.</p><img src="https://counter.theconversation.com/content/197454/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Kleczkowski receives funding from the UKRI and the Scottish Government.</span></em></p>The repeated lesson from other countries is that the loss of immunity and the appearance of new variants make herd immunity a futile goal when it comes to COVID.Adam Kleczkowski, Professor of Mathematics and Statistics, University of Strathclyde Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1899342022-09-21T12:35:27Z2022-09-21T12:35:27ZPolio vaccination rates in some areas of the US hover dangerously close to the threshold required for herd immunity – here’s why that matters<figure><img src="https://images.theconversation.com/files/484423/original/file-20220913-3906-gl2l50.jpg?ixlib=rb-1.1.0&rect=0%2C18%2C4102%2C2990&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In 1956, during the height of the polio epidemic in the U.S., health officials in Chicago offer polio shots at a public school.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/free-chicago-illinois-mrs-rose-stamler-uses-microphone-to-news-photo/514975204?adppopup=true">Bettmann via Getty Images</a></span></figcaption></figure><p>Given recent headlines, you may be wondering why polio is even an issue in 2022. For more than 60 years, vaccines against the poliovirus <a href="https://www.cdc.gov/vaccines/pubs/pinkbook/polio.html#">have protected virtually everyone</a> in the United States from the disease. Due to an enormously successful polio vaccination campaign beginning in the 1950s when the <a href="https://www.who.int/news-room/spotlight/history-of-vaccination/history-of-polio-vaccination">first polio vaccines became available</a>, by 1979 polio was <a href="https://www.cdc.gov/polio/why-are-we-involved/index.htm#">considered eliminated in the U.S.</a> </p>
<p>Unfortunately, even today, there are communities in the U.S. that have lower-than-necessary polio vaccination rates. Because many people have not been vaccinated, there is now a real <a href="https://theconversation.com/fears-of-a-polio-resurgence-in-the-us-have-health-officials-on-high-alert-a-virologist-explains-the-history-of-this-dreaded-disease-189107">possibility of a resurgence of polio in the U.S</a>. </p>
<p>As a <a href="https://scholar.google.com/citations?user=G2EkJJ0AAAAJ&hl=en">clinical professor of pharmacy</a>, I train future pharmacists about how vaccines work, their importance and how they prevent diseases. </p>
<p>Public health experts’ longstanding concerns over falling vaccination rates rose to the surface when, in July 2022, a man from Rockland County, New York, <a href="https://www.cdc.gov/mmwr/volumes/71/wr/mm7133e2.htm">was diagnosed with polio</a>, the first such diagnosis in the U.S. <a href="https://www.nytimes.com/2022/07/21/nyregion/polio-case-new-york.html">in nearly a decade</a>. The patient – who developed the severe, paralytic form of the disease – had been exposed to an <a href="https://theconversation.com/polio-in-new-york-an-infectious-disease-doctor-explains-this-exceedingly-rare-occurrence-187518">altered live vaccine strain from overseas</a>.</p>
<p>Then on Sept. 9, 2022, New York declared a <a href="https://www.governor.ny.gov/executive-order/no-21-declaring-disaster-state-new-york">state of emergency</a> due to ongoing poliovirus transmission. As of that date, using wastewater surveillance, officials had identified <a href="https://health.ny.gov/diseases/communicable/polio/wastewater.htm">57 samples of poliovirus in wastewater</a> from four New York counties. More than half of those were detected in the same county where the adult patient is from, just outside New York City.</p>
<p>As a result of the continued poliovirus detection in wastewater, the Centers for Disease Control and Prevention declared that the U.S. now meets the World Health Organization’s criteria for “a <a href="https://www.cdc.gov/media/releases/2022/s0913-polio.html">country with circulating vaccine-derived poliovirus</a>.”</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/w0YUT0-5mPI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The U.S. has recorded its first case of polio in the U.S. in nearly a decade.</span></figcaption>
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<h2>Two main poliovirus vaccine types</h2>
<p>There are two key types of polio vaccine <a href="https://www.cdc.gov/cpr/polioviruscontainment/diseaseandvirus.htm">in use around the world today</a>. The <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/ipv/">inactivated poliovirus vaccine</a> is given as a shot, and the <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/opv/">oral attenuated (or weakened) poliovirus vaccine</a> is administered as oral drops, sometimes on a sugar cube.</p>
<p>Since 2000, the U.S. has exclusively used the inactivated poliovirus vaccine, which cannot cause disease since it does not contain live virus. But in countries where the poliovirus continues to circulate, <a href="https://polioeradication.org/where-we-work/polio-endemic-countries/">such as Pakistan and Afghanistan</a>, the <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/opv/">oral attenuated poliovirus vaccine</a> is still used. </p>
<p>In <a href="https://polioeradication.org/wp-content/uploads/2016/09/Position-statement_OPVsafety.pdf">extremely rare cases</a>, the weakened live vaccine used in other countries can mutate back into its virulent form and lead to paralysis. This is how the adult in New York is believed to have come into contact with the virus.</p>
<h2>How ‘herd immunity’ for polio is determined</h2>
<p>The degree to which a community is protected from a pathogen like poliovirus comes down to <a href="https://doi.org/10.1001/jama.2020.20895">herd immunity</a>. When a community – the so-called herd – reaches a threshold of immunity, it can prevent the transmission of a pathogen from person to person, thereby quelling the pathogen. </p>
<p>The herd immunity threshold for a given disease is calculated based upon the expected number of individuals who an infected person would spread it to if they were susceptible. The higher the number of individuals who would become infected, the higher the percentage of the community or population that <a href="https://doi.org/10.1093/cid/cir007">needs to be vaccinated</a> to avoid continued spread of the disease. </p>
<p>For poliovirus, researchers estimate that between five and seven individuals would be infected for each case <a href="https://doi.org/10.4161/hv.18444">if those people were susceptible</a>. Based upon these calculations, experts determined that at least 80% of a community or population should be vaccinated against poliovirus to prevent its spread. </p>
<h2>Falling vaccination rates</h2>
<p>Throughout the U.S., vaccination rates for polio vary significantly. </p>
<p>The CDC recommends that infants and young children receive a <a href="https://www.cdc.gov/vaccines/vpd/polio/public/index.html#">four-dose schedule of the inactivated poliovirus vaccine</a> at 2 months, 4 months, 6 to 18 months and 4 to 6 years. For those who begin vaccination later – as older children, teens or adults – three doses is considered to be complete vaccination. This is because three doses of inactivated poliovirus vaccination have been shown to provide <a href="https://www.cdc.gov/vaccines/vpd/polio/hcp/effectiveness-duration-protection.html#">between 99% and 100% protection against severe disease</a>. </p>
<p>Although all U.S. states are currently above the 80% herd immunity threshold for poliovirus, there are areas within the country that include many pockets of unvaccinated or undervaccinated individuals – those who have not received a total of three lifetime doses of the inactivated vaccine.</p>
<p>New York state, for example, holds one of the highest kindergarten polio vaccination rates in the country, <a href="https://www.cdc.gov/vaccines/imz-managers/coverage/schoolvaxview/data-reports/index.html">with 97.9%</a> of kindergartners vaccinated in the 2020-2021 school year. But current estimates by the New York State Department of Public Health suggest that only <a href="https://health.ny.gov/diseases/communicable/polio/county_vaccination_rates.htm">79% of 2-year-olds in that state</a> have received three doses of the polio vaccine. </p>
<p>Further, in certain pockets and counties of New York, such as Rockland, Orange and Sullivan, three-dose vaccination rates may be far lower based on the 2-year-old age group, which is the only data that is available by county: Rockland 60%, Orange 59% and Sullivan 62%. In fact, 46% of counties in New York are below the three-dose poliovirus vaccination <a href="https://health.ny.gov/diseases/communicable/polio/county_vaccination_rates.htm">herd immunity threshold for 2-years-olds</a>. </p>
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<figcaption><span class="caption">Most people today don’t remember the polio outbreak that terrorized Americans during the first half of the 20th century.</span></figcaption>
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<h2>Vaccine recommendations</h2>
<p>When children fall more than one month behind on recommended polio vaccination, doctors recommend routine catch-up throughout adolescence. </p>
<p>Because most adults in the U.S. today were vaccinated as children and the <a href="https://www.cdc.gov/polio/why-are-we-involved/index.htm#">U.S. had eliminated polio as of 1979</a>, there was little reason for health experts to believe an adult would come into contact with poliovirus in the U.S. For that reason, catch-up vaccination for adults has not been included on the routine adult vaccination schedule. </p>
<p>But in August 2022, the CDC updated its guidance. In light of the fact that there are communities where poliovirus vaccination rates have fallen below the 80% threshold needed for herd immunity, coupled with the ongoing circulation of poliovirus in New York, the CDC now recommends that all unvaccinated or undervaccinated adults in these communities <a href="https://www.cdc.gov/vaccines/vpd/polio/public/index.html#">receive a poliovirus vaccination</a>. </p>
<p>Additionally, the CDC suggests that some fully vaccinated adults who are at increased risk of exposure may benefit from a single lifetime poliovirus booster dose. This includes health care providers who care for those with poliovirus, or people traveling to areas where poliovirus has not been eliminated.</p>
<p>If you are unsure if you need vaccination or what steps you should take, talk to your pharmacist or primary care physician.</p><img src="https://counter.theconversation.com/content/189934/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Girotto consults for Lexi-Comp. She has received grant funds from Pfizer to support independent quality improvement specific to outpatient antimicrobial stewardship. </span></em></p>With poliovirus circulating in New York, health authorities worry that pockets of the county with low polio vaccination rates could give the virus a foothold.Jennifer Girotto, Clinical Professor of Pharmacy Practice, University of ConnecticutLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1839182022-06-02T20:26:38Z2022-06-02T20:26:38ZHerd immunity was sold as the path out of the pandemic. Here’s why we’re not talking about it any more<figure><img src="https://images.theconversation.com/files/465611/original/file-20220527-18-dvoa4u.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/little-plastic-blue-toy-figure-stand-1074052646">Shutterstock</a></span></figcaption></figure><p>Early in the pandemic, the term “herd immunity” hit the headlines, along with a polarised discussion on how to achieve it.</p>
<p>Some groups were attached to the <a href="https://theconversation.com/the-herd-immunity-route-to-fighting-coronavirus-is-unethical-and-potentially-dangerous-133765">now-discredited notion</a> of letting a dangerous virus rip through the population to reach the critical level of population immunity needed to reduce transmission.</p>
<p>But a more serious conversation focussed on the prospect of attaining herd immunity by vaccination. </p>
<p>This is the idea that vaccines – when available and taken up at sufficient levels – could squash virus transmission. This would lead to the possible <a href="https://theconversation.com/eradication-elimination-suppression-lets-understand-what-they-mean-before-debating-australias-course-142495">elimination or eradication</a> of SARS-CoV-2, the virus that causes COVID. </p>
<p>The <a href="https://news.harvard.edu/gazette/story/2021/02/vaccines-should-end-the-pandemic-despite-the-variants-say-experts/">promise</a> was this would herald the return of life back to normal.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1368380912644292612"}"></div></p>
<p>It’s understandable why this notion gained so much attention, as it promised a complete return to a world without COVID. But in reality it was probably always a pipe dream.</p>
<p>As time wore on, herd immunity became even less reachable.</p>
<p>Here’s why we’re not talking about it any more, even with the high vaccination rates we see today.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/80-vaccination-wont-get-us-herd-immunity-but-it-could-mean-safely-opening-international-borders-162863">80% vaccination won't get us herd immunity, but it could mean safely opening international borders</a>
</strong>
</em>
</p>
<hr>
<h2>What is herd immunity?</h2>
<p>If enough people in the community develop immunity to an infectious agent such as a virus, an epidemic is unable to grow.</p>
<p>In fact, much like a bushfire goes out when it runs out of fuel to burn, an epidemic <a href="https://theconversation.com/what-is-herd-immunity-and-how-many-people-need-to-be-vaccinated-to-protect-a-community-116355">begins to decline</a> when the virus runs out of susceptible people to infect.</p>
<p>The level of vaccine coverage needed in a population to get you over the line to achieve herd immunity is the “herd immunity threshold”.</p>
<p>This depends on two main parameters – the infectiousness of the virus and the effectiveness of the vaccine. </p>
<p><a href="https://theconversation.com/what-is-herd-immunity-and-how-many-people-need-to-be-vaccinated-to-protect-a-community-116355">In short</a>, the more infectious the virus and the less effective the vaccine, the more people you need to vaccinate to achieve herd immunity.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-herd-immunity-and-how-many-people-need-to-be-vaccinated-to-protect-a-community-116355">What is herd immunity and how many people need to be vaccinated to protect a community?</a>
</strong>
</em>
</p>
<hr>
<h2>Further and further out of reach</h2>
<p>As the pandemic progressed, herd immunity via vaccination moved further and further out of reach. In fact, based on what we know about currently circulating viral variants, today, herd immunity via vaccination is mathematically impossible.</p>
<p>Back at the beginning of 2020, we were grappling with the original strain of SARS-CoV-2, which was much less infectious than current circulating variants. </p>
<p>The original strain had an estimated R0 (basic reproduction number) of <a href="https://www.bmj.com/content/369/bmj.m1891">two to three</a>. That is, someone infected with the virus would spread it to, on average, two to three others.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pins on a board, connected with string" src="https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466508/original/file-20220601-49630-dv2meh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Each person with the ancestral strain of the virus infected two to three others. But later variants infected many more.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/linking-entities-networking-social-media-sns-1044017923">Shutterstock</a></span>
</figcaption>
</figure>
<p>If we assume we were working with a vaccine with an effectiveness of 80%, this yields a herd immunity threshold estimate of 60-80%. That is, when the original strain of the virus was circulating we would have needed to vaccinate 60-80% of the whole population to see the epidemic decline. Mathematically at least, this was not out of reach.</p>
<p>However, as we know, circumstances have changed dramatically over the course of the pandemic, with the original SARS-CoV-2 virus superseded by far more infectious variants.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-is-a-covid-mutation-a-new-variant-and-when-is-it-a-subvariant-and-whats-a-recombinant-182333">When is a COVID mutation a new variant, and when is it a subvariant? And what’s a recombinant?</a>
</strong>
</em>
</p>
<hr>
<p>Although estimates of the infectiousness for the variants are subject to some uncertainty, it is reasonable to assume Delta has a reproduction number of about five and Omicron may be double this, somewhere <a href="https://theconversation.com/new-covid-variants-may-be-more-transmissible-but-that-doesnt-mean-the-r0-or-basic-reproduction-number-has-increased-186826">around 10</a>.</p>
<p>Based on these numbers for Delta and Omicron, the herd immunity threshold estimates go to over 100%. </p>
<p>As you cannot vaccinate more than 100% of the population, you can see how relying on vaccination to achieve herd immunity has become progressively more mathematically impossible as the pandemic progressed.</p>
<h2>That’s not all</h2>
<p>Over the course of the pandemic we have learnt more about how the vaccines have performed in the real world and the nature of our immune response.</p>
<p><strong>Vaccines don’t block all transmission</strong></p>
<p>Herd immunity via vaccination, and the calculations above, assume vaccines stop transmission 100% of the time.</p>
<p>Although vaccines reduce transmission to a <a href="https://theconversation.com/mounting-evidence-suggests-covid-vaccines-do-reduce-transmission-how-does-this-work-160437">significant degree</a>, they do not prevent it completely. If we factor this into our calculations, the challenge to achieve herd immunity becomes harder again.</p>
<p><strong>Immunity wanes over time</strong></p>
<p>Attaining herd immunity also assumes immunity against COVID is maintained long term. But we now know immunity <a href="https://theconversation.com/immunity-to-covid-19-may-not-last-this-threatens-a-vaccine-and-herd-immunity-142556">wanes</a> after vaccination and after natural infection.</p>
<p>So if immunity is not sustained, even if herd immunity were theoretically possible, it would only be transient. Preserving it would only come with significant effort, requiring regular delivery of boosters for the whole population.</p>
<p><strong>New viral variants</strong></p>
<p>Then we’ve seen new <a href="https://theconversation.com/why-are-there-so-many-new-omicron-sub-variants-like-ba-4-and-ba-5-will-i-be-reinfected-is-the-virus-mutating-faster-182274">variants</a> emerge with an ability to evade the immune response. Any change in the immunogenicity of new variants moves the goal posts further away, compromising our ability to achieve herd immunity to an even greater extent.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1374575449918083073"}"></div></p>
<h2>So why are we bothering to vaccinate?</h2>
<p>While attaining herd immunity via vaccination is no longer a realistic proposition, this needs to be put into perspective.</p>
<p><strong>Vaccines go hand-in-hand with other measures</strong></p>
<p>It’s better to consider herd immunity as a gradient rather than a binary concept. That is, even if we don’t reach the herd immunity threshold, the greater the proportion of the population vaccinated, the more difficult it becomes for the virus to spread.</p>
<p>Therefore, vaccination can combine with other behavioural and environmental measures (such as physical distancing, wearing masks and improving ventilation), to substantially impact the ability of the virus to move through the population.</p>
<p><strong>Vaccines protect individuals</strong></p>
<p>Despite the allure of herd immunity, the primary purpose of COVID vaccination has always been to protect individuals from severe illness and death, and thus the impact of disease on the population. </p>
<p>In this regard, despite the waning protection against infection, vaccines appear to afford more <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2115481">sustained protection</a> against severe disease.</p>
<p>So being vaccinated remains as important now as it has always been. Right now, at the start of winter and with few COVID restrictions, it has never been more important to ensure you are fully vaccinated.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-well-do-covid-vaccines-work-in-the-real-world-162926">How well do COVID vaccines work in the real world?</a>
</strong>
</em>
</p>
<hr>
<p><em>Correction: this article originally estimated Omicron had an R0 of around 20, making it among the most infectious diseases known. This has been replaced with the estimate of around 10. The herd immunity threshold has also been updated from up to 100-118% to over 100%.</em></p><img src="https://counter.theconversation.com/content/183918/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hassan Vally does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Achieving herd immunity via vaccination was always going to be a hard ask. Now it’s mathematically impossible.Hassan Vally, Associate Professor, Epidemiology, Deakin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1768422022-03-31T19:29:32Z2022-03-31T19:29:32ZHow we think about immunity can help us navigate COVID-19 risks together<figure><img src="https://images.theconversation.com/files/455651/original/file-20220331-26-pfeipc.jpg?ixlib=rb-1.1.0&rect=724%2C160%2C4643%2C3412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Viewing immunity as a carpet that we weave together evokes labour and artistry, and suggests we have a role in crafting something rather than simply being acted upon by a virus.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/how-we-think-about-immunity-can-help-us-navigate-covid-19-risks-together" width="100%" height="400"></iframe>
<p>Back in February, Peter Jüni, then scientific director of Ontario’s <a href="https://covid19-sciencetable.ca/">Scientific Advisory Table</a>, stated on a CBC Radio <a href="https://www.cbc.ca/listen/live-radio/1-13-cross-country-checkup/clip/15893561-full-episode-is-start-living-covid-19">call-in show</a> that, “We are continuing to weave a carpet of immunity.” </p>
<p>As a health humanities researcher working on how COVID-19 informs our cultural imagining of immunity, I was struck by Jüni’s metaphor. Now, with <a href="https://www.cbc.ca/news/canada/ottawa/dr-peter-juni-stepping-down-science-table-new-job-1.6389800">his impending departure</a> coinciding with the end of mask and vaccine mandates, I find myself considering the metaphor anew. </p>
<p>At a time when authorities are advising individuals to <a href="https://www.tvo.org/transcript/2692413/how-ontarians-have-to-manage-their-own-covid-risk">make their own risk assessments</a> as we head into a <a href="https://globalnews.ca/news/8720190/canada-6th-covid-wave-explainer/">sixth COVID-19 wave</a>, public health messaging has never been more important. </p>
<p>Jüni’s metaphorical “carpet of immunity” conjured up an image of something meticulously crafted and spreading protectively over our region. It also illustrated how the language of public health can invite the public to think differently about immunity, a complex biological system that the pandemic has thrust into daily life.</p>
<h2>Language, metaphor and health</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Grid of 15 different physical distancing signs" src="https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=254&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=254&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=254&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=319&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=319&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455339/original/file-20220330-5922-dqv7gy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=319&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">As we head into a potential sixth wave of COVID-19, individuals are being told to make their own risk assessments.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Jonathan Hayward</span></span>
</figcaption>
</figure>
<p>Language matters. Theorists have been making this argument for decades in relation to <a href="https://us.macmillan.com/books/9780312420130/illnessasmetaphorandaidsanditsmetaphors">cancer</a>, <a href="https://www.dukeupress.edu/how-to-have-theory-in-an-epidemic/">AIDS</a> and the <a href="https://press.uchicago.edu/ucp/books/book/chicago/W/bo14674212.html">cultural representation of disease</a> more generally. Language can often <a href="https://doi.org/10.1093/geront/42.3.293">distort our understanding</a> of fundamental concepts of health and medicine, especially <a href="https://www.penguinrandomhouse.ca/books/204348/flexible-bodies-by-emily-martin/9780807046272">in the case of immunity</a>.</p>
<p>Philipp Dettmer, founder of YouTube science education channel Kurzgesagt and author of <em>Immune</em>, <a href="https://www.bbc.com/news/health-60171592">says of immunity</a>: </p>
<blockquote>
<p>“… people lack a good mental image of what the term means. They think of it as an energy shield that you can charge up. But it is not a thing at all, it’s a multitude of things.” </p>
</blockquote>
<p>As a way of making sense of something we can’t see, metaphor often mediates our understanding of immunity. Seeking a more fitting way of imagining immunity, Eula Biss, author of <em>On Immunity: An Inoculation</em>, proposes the naturalistic image of the “garden” as an alternative to the <a href="https://www.bbc.com/news/health-59260294">standard fortress metaphor</a>. The garden image (based on an <a href="https://doi.org/10.1086/590200">ecological understanding of immunity</a>) suggests something in between the natural and the artificial. As <a href="https://www.graywolfpress.org/books/immunity">Biss explains</a>: </p>
<blockquote>
<p>“The antibodies that generate immunity following vaccination are manufactured in the human body, not in factories. Using ingredients sourced from organisms, once living or still alive, vaccines invite the immune system to produce its own protection.” </p>
</blockquote>
<p>Vaccines are not perfectly natural, but neither are they “unnatural,” despite the arguments of wellness communities. In rejecting vaccines, these groups tend to glorify an idea of <a href="https://www.vox.com/the-goods/22577558/wellness-world-qanon-conspiracy-orientalism">bodily purity</a> based on the frequent misappropriation and <a href="https://www.fridaythings.com/recent-posts/angela-liddon-oh-she-glows-canada-trucker-convoy-2022">misrepresentation</a> of Eastern spirituality. </p>
<p>This notion of the individual body’s ability to boost its “<a href="https://hub.jhu.edu/2021/09/10/infection-from-covid-vs-vaccines/">natural immunity</a>” has further fed resistance to public health measures and restrictions. </p>
<h2>Weaving the carpet</h2>
<p>A garden by its very nature is cultivated but can quite easily run wild if left untended. But a “carpet that we weave together” elegantly evokes labour and artistry. In suggesting that we have a role in crafting something rather than simply being acted upon by a virus, this phrasing offers an antidote, perhaps, to the pandemic-induced feelings of disempowerment seemingly fuelling anti-mandate demonstrations. </p>
<figure class="align-center ">
<img alt="Close-up of a carpet in progress on a loom" src="https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&rect=0%2C129%2C1599%2C1068&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455484/original/file-20220331-17-vmm62y.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Viewing immunity as a carpet that we weave together evokes labour and artistry, and suggests we have a role in crafting something rather than simply being acted upon by a virus.</span>
<span class="attribution"><span class="source">(Wikipedia Commons/Fulvio Spada)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>This metaphor also sidesteps the divide between the artificial and the natural by intertwining both forms of immunity (acquired through either exposure to infection or vaccination) into something figuratively spun on a loom.</p>
<p>Jüni’s metaphor also seemed strategic in its reassuring domesticity: what is more commonplace than a carpet? In this sense, “carpet immunity” rejects <a href="https://www.wbfo.org/binational/2021-04-19/ontario-losing-the-battle-between-the-variants-and-vaccines">politicians</a>’ standard <a href="https://doi.org/10.1080/15265161.2016.1214305">militaristic imagery</a> of vaccines as a front line of defence against COVID-19 and its variants. </p>
<p>In its banality, the image captured what it means to live with the virus. In a biological sense, we “live with” the virus through our immune systems, which had an opportunity to get acquainted with SARS-CoV-2 under the controlled conditions afforded by mandates and vaccine rollouts. </p>
<h2>Immunity as a shared goal and responsibility</h2>
<p>From the early days of the pandemic, public health <a href="https://www.theatlantic.com/ideas/archive/2021/02/how-public-health-messaging-backfired/618147/">struggled with its messaging</a> around mandates. But Jüni’s metaphor clearly calls on us to work together. Emerging from the pandemic, this formulation emphasizes mutual responsibility and invites us to think of immunity in social terms rather than simply individual terms.</p>
<p>However, this is a more difficult undertaking than one might expect. Immunity is informed by and layered over with <a href="https://www.dukeupress.edu/a-body-worth-defending">political</a> and <a href="https://www.politybooks.com/bookdetail?book_slug=immunitas-the-protection-and-negation-of-life--9780745649139">legal meanings</a> stretching as far back as ancient Rome and filtered through <a href="https://doi.org/10.1186/1747-5341-5-1">Enlightenment thought</a>. </p>
<p>As gender studies professor Ed Cohen reflects in <a href="https://www.dukeupress.edu/a-body-worth-defending"><em>A Body Worth Defending</em></a>, an idea of “immunity-as-defence” charged with maintaining clear boundaries around the individual has been fixed in western thinking since the 19th century. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People at a vaccine mandate protest holding signs" src="https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455347/original/file-20220330-5413-c08ea5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Anti-vaccination discourse positions the robust, sovereign body as impervious to both infection and accountability.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Lars Hagberg</span></span>
</figcaption>
</figure>
<p>Interestingly, the “immunity as carpet” phrasing has to date been applied to immunity in precisely this original, legal sense. A quick Google search reveals multiple usages of the phrase “<a href="https://thenationonlineng.net/re-traditionalisation-globalisation-politics/">red carpet of immunity</a>” to signify the exemption of high-profile politicians and executives from prosecution. In this double sense, anti-vaccination discourse positions the robust, <a href="https://www.theguardian.com/commentisfree/2021/sep/22/leftwingers-far-right-conspiracy-theories-anti-vaxxers-power">sovereign body</a> as impervious to both infection and accountability. </p>
<p>Yet scientists’ imagining of <a href="https://www.ncbi.nlm.nih.gov/books/NBK538382/">collective immunity</a> posits exactly the opposite of exemption (in a social rather than medical sense). “<a href="https://www.un.org/en/un-coronavirus-communications-team/we-are-all-together-human-rights-and-covid-19-response-and">We are all in this together</a>,” we are told, with the same basic biology, entangled <a href="https://read.dukeupress.edu/books/book/1261/ContagiousCultures-Carriers-and-the-Outbreak">by webs of contact</a> and the traces we leave behind. </p>
<p>The idea of “carpet immunity” captures the varied <a href="https://doi.org/10.1093/beheco/arq070">complexities of shared immune systems</a>. It is in its own way a unifying image in the weaving together of infection- and vaccination-induced antibodies. Taken together, these antibodies may over time give our society <a href="https://doi.org/10.1128/mBio.02656-21">some measure of protection</a> against Omicron, its currently surging <a href="https://www.cbc.ca/news/canada/saskatchewan/omicron-subvariant-ba2-1.6393804">subvariant BA.2</a> and subsequent strains of the novel coronavirus. </p>
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Read more:
<a href="https://theconversation.com/how-new-covid-19-variants-emerge-natural-selection-and-the-evolution-of-sars-cov-2-176030">How new COVID-19 variants emerge: Natural selection and the evolution of SARS-CoV-2</a>
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<p>Finally, “a carpet we weave together” evokes an image of artisans working in close proximity to create something both functional and ornamental. This collectivist metaphor offers an esthetically appealing alternative to the more familiar “herd immunity” increasingly seen as <a href="https://www.ctvnews.ca/health/coronavirus/omicron-highlights-fading-hope-of-herd-immunity-from-covid-19-1.5747676">out of reach</a>. It invites us to imagine immunity as a collaborative project, spreading out to protect those among us for whom the end of mandates means <a href="https://www.tvo.org/article/ending-mask-mandates-is-a-betrayal-of-disabled-ontarians">increased vulnerability</a>. </p>
<p>Most importantly, this language challenges us to imagine what a post-pandemic future might look like if we commit to continuing to craft a “carpet of immunity” through vaccination, rather than unravelling it while it remains a work in progress. As Peter Jüni prepares to step down from the Ontario COVID-19 Science Advisory Table, he leaves behind a model for how effective public health messaging can reshape ideas about both our bodies and our communities and affect our everyday practices (if we choose to listen).</p><img src="https://counter.theconversation.com/content/176842/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kelly McGuire receives funding from the Social Sciences and Humanities Research Council of Canada. </span></em></p>The metaphor of a collective “carpet of immunity” invites us to imagine immunity as a collaborative project, spreading out to protect those for whom the end of mandates means increased vulnerability.Kelly McGuire, Associate Professor of Gender & Social Justice and English, Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1797982022-03-24T20:00:19Z2022-03-24T20:00:19ZPandemic vaccine passports in Canada: A brief history and potential future<figure><img src="https://images.theconversation.com/files/453987/original/file-20220323-17-r3rrfp.jpg?ixlib=rb-1.1.0&rect=0%2C184%2C5955%2C4125&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">B.C. Jobs Minister Ravi Kahlon has his COVID-19 vaccine QR code scanned in September, 2021.</span> <span class="attribution"><span class="source">THE CANADIAN PRESS/Darryl Dyck</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/pandemic-vaccine-passports-in-canada--a-brief-history-and-potential-future" width="100%" height="400"></iframe>
<p>The simple idea of tracking and requiring proof of vaccination created some of the most <a href="https://www.cbc.ca/news/politics/anti-mandate-protests-cripple-canada-us-trade-1.6345414">disruptive protests</a> in Canadian history, and the declaration of a <a href="https://www.cbc.ca/news/politics/trudeau-premiers-cabinet-1.6350734">national emergency</a>.</p>
<p>How did this happen? It’s complicated.</p>
<p>It’s easy to forget that, at the outset of the pandemic, the initial lockdowns were extremely harsh and had a severe <a href="https://www.bankofcanada.ca/2021/05/staff-analytical-note-2021-8/">impact on economies</a> and <a href="https://www150.statcan.gc.ca/n1/pub/11-631-x/11-631-x2021001-eng.htm">people’s lives</a>. In attempts to mitigate these effects while protecting the health of populations, the idea of natural immunity passports was considered. </p>
<p>There were many scientific questions about this approach, including how to determine if someone was infected and how long immunity would last. And there were also <a href="https://www.cbc.ca/news/opinion/opinion-pandemic-coronavirus-immunity-passport-1.5551528">important ethical questions</a> to consider, such as creating incentives to be infected and creating a two-tier society.</p>
<p>This idea <a href="https://globalnews.ca/news/6868198/coronavirus-immunity-passports-canada-trudeau/">didn’t move forward for several reasons</a>, not the least of which was because so few people had evidence of infection, for this approach to have any value.</p>
<h2>Vaccine-induced immunity</h2>
<p>Flash forward to the publication of the Phase 3 studies for the mRNA vaccines. The results were better than many expected: 95 per cent protection against symptomatic infection. The idea of proof of immunity was revisited, but this time it was <a href="https://www.priv.gc.ca/en/opc-news/speeches/2021/s-d_20210519/">vaccine-induced immunity</a>. </p>
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<img alt="People carrying signs reading 'No more tax pass' and 'Make Canada free again' in front of a parked trucks" src="https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453984/original/file-20220323-27-1as5ekg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Protests against vaccine mandates led to a state of emergency in Ontario in February.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Justin Tang</span></span>
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<p>However, the argument against it now was that if the vaccine was that effective, individuals <a href="https://www.factcheck.org/2021/09/covid-19-the-unvaccinated-pose-a-risk-to-the-vaccinated/">wouldn’t need others to be vaccinated, if they were vaccinated themselves</a>. Also, based on the transmission rate of the original strain of the virus, the <a href="https://doi.org/10.1038/d41586-021-00728-2">herd immunity threshold was in the 60-70 per cent range</a>, which was potentially achievable through voluntary programs. </p>
<p>The Delta variant changed this calculus and became the poster child for vaccine passports. Vaccine <a href="https://doi.org/10.1136/bmj.n1960">effectiveness dropped</a> to the 70 per cent range against infection, and the <a href="https://www.cbc.ca/news/canada/ottawa/covid-19-unvaccinated-final-push-herd-immunity-delta-1.6113769">herd immunity threshold increased to 90 per cent range</a>, a target that would be challenging without mandates of some sort. Furthermore, the Delta variant was causing serious illness in broader segments of the population and hospitals. In particular, <a href="https://doi.org/10.1503/cmaj.211248">intensive care units</a> were being overwhelmed.</p>
<p>Reluctant Conservative governments had no choice but to <a href="https://nationalpost.com/news/canada/hit-a-wall-kenney-relents-on-vaccine-passports-to-mitigate-alberta-hospitals-grave-collapse">acquiesce to vaccine passports</a>. When a federal election was called, this was a <a href="https://www.cbc.ca/radio/thehouse/vaccine-passport-king-vaughan-the-house-1.6180018">key platform issue</a> of the Liberal party. </p>
<p>As a physician innovator in <a href="https://www.canimmunize.ca/en/about">digital immunization records</a> with expertise in <a href="https://www.ottawahealthlaw.ca/faculty">health law, policy and ethics</a>, I understood the challenges in balancing public health benefits with individuals rights and freedoms. </p>
<p>At that time, my thoughts were that the reason to have mandates was primarily for settings in which the virus could spread easily. During the Delta wave, stories of <a href="https://globalnews.ca/news/7921830/ontario-covid-peel-region-delta-variant/">vulnerable essential workers</a> contracting the virus in warehouses and <a href="https://globalnews.ca/news/7754875/cargill-london-ont-covid-19-outbreak/">meat packing plants</a> and spreading it to their families who fell seriously ill, were terrible. </p>
<p>In my mind, you simply could not allow individuals to go to these high-risk settings unvaccinated. However, the <a href="https://news.ontario.ca/en/release/1000750/ontario-makes-covid-19-vaccination-policies-mandatory-for-high-risk-settings">broader application of the policy</a> also resulted in increased vaccination rates, and helped control the Delta wave.</p>
<h2>The spread of Omicron</h2>
<p>The Omicron wave changed the story again. Omicron was milder, but more infectious. But more importantly, two doses of vaccine provided <a href="http://doi.org/10.1056/NEJMoa2119451">minimal protection against infection</a>, although it did <a href="https://www.aamc.org/news-insights/omicron-and-vaccines-your-questions-answered">protect against serious illness and death</a>. </p>
<p>The rationale for vaccine passports was now different. Herd immunity through vaccination alone was unattainable. If the goal was to prevent transmission to others, any mandate should be three vaccines which <a href="https://doi.org/10.1038/d41586-022-00214-3">provide 60-70 per cent protection against infection</a>. However, if the goal is to protect against serious illness then two doses provided reasonable protection, although this would be improved with a booster. </p>
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<img alt="A man in a mask uses a smartphone to scan another smartphone held by a woman in a mask" src="https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453988/original/file-20220323-25-djwvbo.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A customer has their proof of vaccination scanned entering a restaurant in Montréal in September, 2021.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Graham Hughes</span></span>
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<p>And here is where it gets complicated. People not wishing to be vaccinated could argue that an unvaccinated person was no more likely to become infected by Omicron than a two-dose vaccinated person. </p>
<p>Unfortunately, our fragile health-care system complicates this decision. Individuals getting seriously ill place strains on hospitals, health-care workers and have spillover effects, including the cancellation of medical procedures. And, <a href="https://www.reuters.com/world/americas/canadas-ontario-province-announces-curbs-prevent-spread-omicron-tsunami-2022-01-03/">as we saw with the “mild” Omicron wave</a>, this triggers a lockdown which affects all of us.</p>
<h2>Future policy</h2>
<p>So where do we go from here? I think we will end on a middle ground for a potentially endemic virus. This could mean a policy <a href="https://doi.org/10.1503/cmaj.202755">already in use for health-care workers</a> and the influenza vaccine: You don’t neccesarily have to be vaccinated, but if there are cases at work or at school, you and your child will be asked to stay home for your own protection. This may vary based on the risk to your demographic. Proof of previous infection may be also considered in these policies. </p>
<p><a href="https://www.cbc.ca/news/health/canada-vaccine-mandate-passport-covid-19-omicron-boosters-1.6349038">Vaccine passports did work</a>. They increased vaccination rates, saved countless lives and reduced the duration of lockdowns, preserving parts of the economy.</p>
<p>But, as we have seen, these policies are highly divisive and are impacted by the changing science of the pandemic, which will require more targeted and adaptable approaches moving forward. And importantly, the messaging around these policies will need to change from penalizing the sub-optimally vaccinated to protecting them.</p><img src="https://counter.theconversation.com/content/179798/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kumanan Wilson is the Chief Executive Officer of CANImmunize Inc. Dr Wilson served as a member of the independent data monitoring committee for the Medicago COVID-19 vaccine trial. Dr Wilson has received funding from the Canadian Institutes of Health Research, the Canadian Immunity Task Force, the World Health Organization and the Bill & Melinda Gates Foundation.
Dr Wilson is an internal medicial physician at The Ottawa Hospital, Professor of Medicine and Chair in Digital Health Innovation at the University of Ottawa, an innovation advisor at Bruyere Hospital and CEO of CANImmunize Inc. He is a member of the University of Ottawa Centre for Health Law, Policy and Ethics.</span></em></p>Vaccine passports became one of the most divisive issues of the COVID-19 pandemic. These policies were affected not only by public opinion but by new variants and changing goals for herd immunity.Kumanan Wilson, Professor of Medicine, physician, scientist, Ottawa Hospital Research Institute, L’Université d’Ottawa/University of OttawaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1790602022-03-17T12:10:24Z2022-03-17T12:10:24ZHow does the immune system mobilize in response to a COVID-19 infection or a vaccine? 5 essential reads<figure><img src="https://images.theconversation.com/files/452348/original/file-20220316-16-12d1gnq.jpg?ixlib=rb-1.1.0&rect=231%2C52%2C6774%2C4810&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The COVID-19 pandemic has taught most people more than they ever expected to know about immunology.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/coronavirus-structural-morphology-royalty-free-image/1215480593">Membio/iStock via Getty Images Plus</a></span></figcaption></figure><p>Heading into the third year of the COVID-19 pandemic, many of us have become amateur immunologists, having conversations at the dinner table and in the grocery store aisle about <a href="https://theconversation.com/how-mrna-vaccines-from-pfizer-and-moderna-work-why-theyre-a-breakthrough-and-why-they-need-to-be-kept-so-cold-150238">mRNA vaccines</a>, <a href="https://theconversation.com/will-omicron-the-new-coronavirus-variant-of-concern-be-more-contagious-than-delta-a-virus-evolution-expert-explains-what-researchers-know-and-what-they-dont-169020">variants</a>, <a href="https://theconversation.com/what-is-a-breakthrough-infection-6-questions-answered-about-catching-covid-19-after-vaccination-164909">breakthrough infections</a>, <a href="https://theconversation.com/how-long-does-protective-immunity-against-covid-19-last-after-infection-or-vaccination-two-immunologists-explain-177309">“waning” immunity</a>, <a href="https://theconversation.com/what-is-herd-immunity-a-public-health-expert-and-a-medical-laboratory-scientist-explain-170520">herd immunity</a>, <a href="https://theconversation.com/is-covid-19-here-to-stay-a-team-of-biologists-explains-what-it-means-for-a-virus-to-become-endemic-168462">endemic viruses</a>, <a href="https://theconversation.com/tense-decision-making-as-cdc-joins-fda-in-recommending-pfizer-booster-shot-for-65-and-up-people-at-high-risk-and-those-with-occupational-exposure-to-covid-19-168703">booster shots</a> and much more. </p>
<p>Many of the stories that we’ve published over the past two years here at The Conversation have stemmed from our own head-scratching questions that came up in our morning news meetings or were posed to us directly by curious readers. We sought out scholars who could take our readers on deep dives into immunology and virology to help demystify these sometimes confusing, conflicting and taxing science-based questions.</p>
<p>Here are five stories from The Conversation’s archives that highlight critical insights that we as editors and readers have gained thanks to COVID-19, and that will no doubt continue to be an important part of our pandemic lexicon. </p>
<h2>1. COVID-19 vaccines explained</h2>
<p>Understanding how vaccines can “trick” the body into mounting an effective immune response against a perceived or actual threat is one of the most fascinating aspects of immunology. “The most important thing to understand about vaccines is that they <a href="https://theconversation.com/what-happens-when-the-covid-19-vaccines-enter-the-body-a-road-map-for-kids-and-grown-ups-164624">teach your body how to gear up to fight an infection</a>, without your body having to deal with the infection itself,” writes <a href="https://scholar.google.com/citations?user=YpknwWcAAAAJ&hl=en">Glenn J. Rapsinski</a>, a pediatric infectious diseases fellow at the University of Pittsburgh Health Sciences. “In this way, vaccines help your body be prepared for invasions by germs that could otherwise make you very sick.”</p>
<p>Rapsinski explains how the COVID-19 vaccines available in the U.S. emulate the spike protein of SARS-CoV-2, the virus that causes COVID-19. “SARS-CoV-2 is a round virus, with bumps all over it – sort of like a baseball covered in golf tees. The bumps are the spike proteins.”</p>
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Read more:
<a href="https://theconversation.com/what-happens-when-the-covid-19-vaccines-enter-the-body-a-road-map-for-kids-and-grown-ups-164624">What happens when the COVID-19 vaccines enter the body – a road map for kids and grown-ups</a>
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<h2>2. And then came breakthrough infections</h2>
<p>Soon after the relief that came with the widespread availability of vaccines in the spring of 2021, we were introduced to the idea of “breakthrough infections,” which were the rare cases in which fully vaccinated people got infected with COVID-19. </p>
<p>“<a href="https://theconversation.com/what-is-a-breakthrough-infection-6-questions-answered-about-catching-covid-19-after-vaccination-164909">Breakthrough infections</a> are a little more frequent than previously expected and are probably increasing because of growing dominance of the delta variant,” <a href="https://scholar.google.com/citations?user=F8vQ9xIAAAAJ&hl=en">Sanjay Mishra</a>, a cancer and vaccine researcher from Vanderbilt University, wrote in July 2021. “But infections in vaccinated people are still very rare and usually cause mild or no symptoms.” </p>
<p>Although breakthrough infections became far more common late in 2021, in part because of the emergence of the highly transmissible omicron variant – more on that down below – COVID-19 vaccines still continue to provide robust protection against the most severe forms of COVID-19 that lead to hospitalization and death.</p>
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Read more:
<a href="https://theconversation.com/what-is-a-breakthrough-infection-6-questions-answered-about-catching-covid-19-after-vaccination-164909">What is a breakthrough infection? 6 questions answered about catching COVID-19 after vaccination</a>
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<h2>3. The growing list of variants</h2>
<p>In 2020 and 2021, new strains of SARS-CoV-2 seemed to emerge faster than people could keep up with their Greek names. But by mid-2021, the highly transmissible delta variant had become the dominant strain in the U.S. and was responsible for the growing number of breakthrough infections. The continual emergence of variants was and is concerning, because it raises questions about how robust one’s immune protection will be from prior infections or from the COVID-19 vaccines, which were based on the original strain of the virus. </p>
<p>The delta variant was between 40% and 60% more transmissible than the alpha variant that it replaced and nearly <a href="https://theconversation.com/will-omicron-the-new-coronavirus-variant-of-concern-be-more-contagious-than-delta-a-virus-evolution-expert-explains-what-researchers-know-and-what-they-dont-169020">twice as transmissible as the original SARS-CoV-2</a> virus, wrote <a href="https://scholar.google.com/citations?user=dqahf8oAAAAJ&hl=en">Suresh V. Kuchipudi</a>, a professor of emerging infectious diseases at Penn State. </p>
<p>But then, of course, came omicron, which was even more contagious than delta, thanks in part to its high number of mutations. “Omicron is very unusual in that it is by far the most heavily mutated variant yet of SARS-CoV-2, the virus that causes COVID-19,” Kuchipudi explained. “The omicron variant has 50 mutations overall, with 32 mutations on the spike protein alone. The spike protein – which forms protruding knobs on the outside of the SARS-CoV-2 virus – helps the virus adhere to cells so that it can gain entry.”</p>
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Read more:
<a href="https://theconversation.com/will-omicron-the-new-coronavirus-variant-of-concern-be-more-contagious-than-delta-a-virus-evolution-expert-explains-what-researchers-know-and-what-they-dont-169020">Will omicron – the new coronavirus variant of concern – be more contagious than delta? A virus evolution expert explains what researchers know and what they don't</a>
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<h2>4. Putting ‘endemic’ viruses into context</h2>
<p>At some point in 2021 – the year is one big blur – we entered a phase of the pandemic where it became clear that we were stuck with COVID-19 for the foreseeable future. For many people, there was a mental shift from the assumption that we could eradicate the coronavirus that causes COVID-19 through vaccination, into the slow realization that it just wasn’t going away. Virologists and other researchers began using the term “endemic” to describe the way that some viruses can fade away but still maintain a low level of transmission in a community. </p>
<p><a href="https://scholar.google.com/citations?user=XY7DNtgAAAAJ&hl=en">Sara Sawyer</a>, <a href="https://experts.colorado.edu/display/fisid_166880">Arturo Barbachano-Guerrero</a> and <a href="https://scholar.google.com/citations?user=l2lpnYkAAAAJ&hl=en">Cody Warren</a>, a team of virologists and immunologists <a href="https://theconversation.com/is-covid-19-here-to-stay-a-team-of-biologists-explains-what-it-means-for-a-virus-to-become-endemic-168462">from the University of Colorado Boulder explain</a> that SARS-CoV, the coronavirus that set off the SARS pandemic in 2003, was less contagious than SARS-CoV-2 and was brought under control relatively quickly by speedy public health measures that ultimately drove the virus extinct. </p>
<p>On the other hand, they wrote, “pandemic viruses may also gradually settle into a relatively stable rate of occurrence, maintaining a constant pool of infected hosts capable of spreading the virus to others.” Such viruses are said to be “endemic” – as will likely become the case with the coronavirus that causes COVID-19.</p>
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Read more:
<a href="https://theconversation.com/is-covid-19-here-to-stay-a-team-of-biologists-explains-what-it-means-for-a-virus-to-become-endemic-168462">Is COVID-19 here to stay? A team of biologists explains what it means for a virus to become endemic</a>
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<h2>5. Immune defenses shift over time</h2>
<p>As 2021 waned, so – apparently – did protective antibodies against COVID-19. Researchers began to learn more about how the immune response shifts in the months following COVID-19 infection or vaccination. And it became clear that over time, people became more vulnerable to getting reinfected or having a breakthrough infection following vaccination – in part because of the emergence of variants.</p>
<p>But antibodies are only <a href="https://theconversation.com/how-long-does-protective-immunity-against-covid-19-last-after-infection-or-vaccination-two-immunologists-explain-177309">part of the immune system’s protective defense</a>, explain <a href="https://scholar.google.com/citations?user=jJVj3sUAAAAJ&hl=en">Prakash Nagarkatti</a> and <a href="https://scholar.google.com/citations?user=af7TahQAAAAJ&hl=en">Mitzi Nagarkatti</a>, a husband-and-wife team of immunologists from the University of South Carolina. </p>
<p>“Throughout the COVID-19 pandemic, the public has widely and mistakenly believed that antibodies provide the bulk of protective immunity, while not recognizing the important role of killer T cells,” they write. “This is in part because antibodies are easy to detect, whereas killer T-cell detection is complex and involves advanced technology. When antibodies fail, it is the killer T cells that are responsible for preventing the more severe outcomes of COVID-19, such as hospitalization and death.”</p>
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Read more:
<a href="https://theconversation.com/how-long-does-protective-immunity-against-covid-19-last-after-infection-or-vaccination-two-immunologists-explain-177309">How long does protective immunity against COVID-19 last after infection or vaccination? Two immunologists explain</a>
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<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/179060/count.gif" alt="The Conversation" width="1" height="1" />
The COVID-19 pandemic has brought immunology terms that are typically relegated to textbooks into our everyday vernacular. These stories helped us make sense of the ever-evolving science.Amanda Mascarelli, Senior Health and Medicine EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1754962022-01-27T13:28:42Z2022-01-27T13:28:42ZIs the omicron variant Mother Nature’s way of vaccinating the masses and curbing the pandemic?<figure><img src="https://images.theconversation.com/files/442657/original/file-20220126-17-75f6ee.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7592%2C3940&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Preliminary research suggests that the omicron variant may potentially induce a robust immune response.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/coronavirus-royalty-free-image/1357650209?adppopup=true">Olga Siletskaya/Moment via Getty Images</a></span></figcaption></figure><p>In the short time since the omicron variant was <a href="https://www.cnn.com/2021/12/02/world/south-africa-omicron-origins-covid-cmd-intl/index.html">identified in South Africa</a> in November 2021, <a href="https://doi.org/10.12998/wjcc.v10.i1.1">researchers have quickly learned</a> that it has three unique characteristics: It spreads efficiently and quickly, it generally causes milder disease than previous variants and it may confer strong protection against other variants such as delta. </p>
<p>This has many people wondering whether omicron could act as a vaccine of sorts, inoculating enough people to effectively bring about <a href="https://theconversation.com/what-is-herd-immunity-a-public-health-expert-and-a-medical-laboratory-scientist-explain-170520">herd immunity</a> – the threshold at which enough of the population is immune to the virus to stop its spread – and end the COVID-19 pandemic.</p>
<p>As <a href="https://sc.edu/study/colleges_schools/medicine/about_the_school/faculty-staff/nagarkatti_mitzi.php">immunology researchers</a> at the University of South Carolina who are <a href="https://pubmed.ncbi.nlm.nih.gov/?term=nagarkatti+p&sort=date&size=200&show_snippets=off">working on inflammatory and infectious diseases</a>, including COVID-19, we find the characteristics of omicron in the pandemic setting particularly intriguing. And it is these characteristics that can help answer that question. </p>
<p>Some 4.73 billion people across the globe – about 61.6% of the world’s population – have received at least <a href="https://www.nytimes.com/interactive/2021/world/covid-vaccinations-tracker.html">one dose of a COVID-19 vaccine</a>. In the United States, 63.4% of the population <a href="https://covid.cdc.gov/covid-data-tracker/#vaccinations_vacc-total-admin-rate-total">is fully vaccinated with two doses</a> as of late January 2022, while only 39.9% of Americans have received the booster dose. Such low levels of vaccination resulting from <a href="https://data.cdc.gov/stories/s/Vaccine-Hesitancy-for-COVID-19/cnd2-a6zw/">vaccine hesitancy</a> and the complexities of the <a href="https://dx.doi.org/10.1016%2Fj.ijpe.2021.108193">global vaccine supply chain</a> cast doubt on reaching <a href="https://theconversation.com/what-is-herd-immunity-a-public-health-expert-and-a-medical-laboratory-scientist-explain-170520">herd immunity</a> through vaccination anytime soon. </p>
<h2>How does omicron mimic a vaccine?</h2>
<p><a href="https://www.hhs.gov/immunization/basics/types/index.html">All vaccines</a> work on the principle of training the immune system to fight against an infectious agent. Each vaccine, regardless of how it is made, exposes the human or animal host to the critical molecules used by the infectious agent – in this case, the SARS-CoV-2 virus – to gain entry into the host’s cells.</p>
<p>Some vaccines expose the host only to select portions of the virus. For example, the Pfizer-BioNTech and Moderna vaccines use a <a href="https://theconversation.com/how-mrna-vaccines-from-pfizer-and-moderna-work-why-theyre-a-breakthrough-and-why-they-need-to-be-kept-so-cold-150238">molecule called messenger RNA</a>, or mRNA, to encode and produce a fragment of the “spike protein” – the knobby protrusion that is expressed on the outside of SARS-CoV-2 viruses – inside a person’s body. These spike proteins are the key way that <a href="https://theconversation.com/what-happens-when-the-covid-19-vaccines-enter-the-body-a-road-map-for-kids-and-grown-ups-164624">the coronavirus invades cells</a>, so the mRNA vaccines are designed to mimic that protein and trigger an immune response against it. </p>
<p>In contrast, some vaccines against other infections, <a href="https://theconversation.com/the-chickenpox-virus-has-a-fascinating-evolutionary-history-that-continues-to-affect-peoples-health-today-168636">such as chickenpox</a> and <a href="https://www.cdc.gov/vaccines/hcp/vis/vis-statements/mmr.html">measles, mumps and rubella (MMR)</a>, expose the host to a “live attenuated” form of the virus. These vaccines use small amounts of a weakened form of the live virus. They mimic a natural infection, trigger a strong immune response and afford lasting resistance to infection. </p>
<p>In some respects, omicron mimics these live attenuated vaccines because it causes milder infection and trains the body to trigger a strong immune response against the delta variant, as shown in a recent <a href="https://doi.org/10.1101/2021.12.27.21268439">study that is not yet peer-reviewed</a> from South Africa. </p>
<h2>Deliberate infection with omicron is not the answer</h2>
<p>While omicron may share certain characteristics with a vaccine, it should not be considered a viable alternative to the existing vaccines. For one, COVID-19 infection can result in <a href="https://www.nytimes.com/live/2022/01/10/world/omicron-covid-testing-vaccines">severe illness, hospitalization or death</a>, especially in <a href="https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medical-conditions.html">vulnerable individuals with underlying conditions</a>. It can also cause long-term health effects in some people, called <a href="https://theconversation.com/deciphering-the-symptoms-of-long-covid-19-is-slow-and-painstaking-for-both-sufferers-and-their-physicians-164754">long COVID</a>. In contrast, vaccines currently available against COVID-19 have been tested for safety and efficacy. </p>
<p>The high transmission of omicron combined with ongoing vaccination efforts could help attain herd immunity soon and end the most acute phase of the pandemic. However, there is little chance of it eradicating COVID-19, since all signs point to the likelihood that the virus <a href="https://theconversation.com/is-covid-19-here-to-stay-a-team-of-biologists-explains-what-it-means-for-a-virus-to-become-endemic-168462">will become endemic</a> – meaning SARS-CoV-2 will be in circulation but will likely not be as disruptive to society.</p>
<p>Thus far, smallpox is the only infectious disease that <a href="https://www.cdc.gov/smallpox/index.html#">has been eradicated globally</a>, which shows how difficult it is to fully eliminate a disease. However, it is easier to control an infection effectively. One example is <a href="https://www.cdc.gov/polio/what-is-polio/polio-us.html">polio</a>, which has been reduced or eliminated in most countries through vaccination. </p>
<h2>What happens when the body meets a virus or vaccine</h2>
<p>Both viral infections or the mimicking of a virus through vaccination activate a critical component of the immune system, called B cells, in the body. These cells produce antibodies that bind to the virus, preventing it from infecting cells. These antibodies act much like anti-ballistic missiles that shoot down an incoming virus missile. However, once a virus manages to get inside the body’s cells, antibodies are less effective. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A 3-D illustration of antibody proteins attacking a coronavirus pathogen cell." src="https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442658/original/file-20220126-13-ngm9rq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Antibodies behave similarly to anti-ballistic missiles, shooting down their target – in this case, the SARS-CoV-2 virus.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/immunoglobulin-or-antibody-proteins-attack-a-corona-royalty-free-image/1299604801?adppopup=true">Christoph Burgstedt/iStock via Getty Images Plus</a></span>
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<p>That’s where another key player in the immune system, called killer T cells, come in. These cells can recognize and destroy a cell as soon as it is infected, thereby preventing the virus from multiplying and spreading further. Think of this as an anti-ballistic missile that detects and destroys the factory where missiles are manufactured. </p>
<p>Immunologists believe that antibodies against COVID-19 prevent an individual from catching the infection, while the <a href="https://www.nature.com/articles/d41586-021-00367-7">killer T cells are crucial</a> in preventing severe disease. Despite its numerous mutations, omicron can trigger a <a href="https://www.nature.com/articles/d41586-022-00063-0#">strong killer T cell response</a>. This may explain why the COVID-19 vaccines – by triggering the T cells – have provided strong enough immunity against omicron to, in most cases, <a href="https://doi.org/10.1001/jamanetworkopen.2021.42725">prevent hospitalization and death</a>.</p>
<p>But, critically, the first wave of antibodies and killer T cells produced during infection or vaccination last for only a few months. This is why recurrent infections of COVID-19 have occurred even in the vaccinated population, and it’s also <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/booster-shot.html">why booster shots are needed</a>. In contrast, some vaccines – like the one against smallpox – have been shown to trigger immunity that lasts for several years. </p>
<h2>Memory immune response</h2>
<p>So what exactly triggers strong and lasting immunity? The lifelong immunity seen in certain infections such as smallpox can be explained by a phenomenon called “<a href="https://www.ncbi.nlm.nih.gov/books/NBK27158/">immunological memory</a>.”</p>
<p>After the B cells and killer T cells first encounter the virus, some of them get converted into what are called memory cells, which are known to <a href="https://doi.org/10.1038/nm917">live for several decades</a>. As their name suggests, when memory cells “see” a virus again after initial exposure, they recognize it, divide rapidly and mount a robust antibody and killer T cell response, thereby preventing reinfection.</p>
<p>[<em>Over 140,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-140ksignup">Sign up today</a>.]</p>
<p>For this reason, memory cells are critical for establishing strong, long-lasting immunity. This is evidenced from studies with smallpox in which people that were infected or vaccinated were found to have the antibody response <a href="https://dx.doi.org/10.1016%2Fj.amjmed.2008.08.019">even after 88 years</a>! Why some infections or vaccines trigger long-lasting memory and others do not is under active investigation. Because COVID-19 is only two years old, we researchers don’t know yet how long the memory B and T cells last. Based on recurrent infections, it looks like longer-term immunity does not last very long, but that could also in part be due to the evolution of new variants. </p>
<p>All of these considerations leave room for hope that when new variants of SARS-CoV-2 inevitably arise, omicron will have left the population better equipped to fight them. So the COVID-19 vaccines combined with the omicron variant could feasibly move the world to a new stage in the pandemic – one where the virus doesn’t dominate our lives and where hospitalization and death are far less common.</p><img src="https://counter.theconversation.com/content/175496/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prakash Nagarkatti receives funding from the National Institutes of Health and the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Mitzi Nagarkatti receives funding from the National Institutes of Health.</span></em></p>Some of the omicron variant’s unique properties – such as its ability to spread rapidly while causing milder COVID-19 infections – could usher in a new phase of the pandemic.Prakash Nagarkatti, Professor of Pathology, Microbiology and Immunology, University of South CarolinaMitzi Nagarkatti, Professor of Pathology, Microbiology and Immunology, University of South CarolinaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1751372022-01-24T19:11:10Z2022-01-24T19:11:10ZWill an Omicron-specific vaccine help control COVID? There’s one key problem<p>In November last year, Australians began to feel a wave of optimism that COVID would no longer define their everyday existence.</p>
<p>Soaring vaccination rates provided some measure of confidence the threat from COVID was beginning to recede.</p>
<p>But by mid-December, this wave of hope had been swept away by a surge of Omicron infections.</p>
<p>Emerging research showed there was <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1048395/technical-briefing-34-14-january-2022.pdf">only around 20% protection from Omicron infection</a> four months after two doses of AstraZeneca, Pfizer or Moderna vaccines (though protection against hospitalisation and death remains much higher, and a booster dose increases protection against infection, but possibly only short-term).</p>
<p>Since the emergence of Omicron, both <a href="https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-provide-update-omicron-variant">Pfizer</a> and <a href="https://www.pharmaceutical-technology.com/news/moderna-eyes-covid-19-flu-booster-2023/">Moderna</a> have announced they’re working on vaccines to specifically target the variant, with production promised as early as March of this year.</p>
<p>So, are variant-specific vaccines the way we regain control of COVID?</p>
<p>A vaccine targeting Omicron will increase immunity to the variant on both an individual and population level.</p>
<p>However, variant-specific vaccines are ultimately a reactive measure that could always leave us behind the eight ball. By the time we roll out any variant-specific vaccine, a wave of infections driven by that variant may already have peaked, and a new variant will likely be on the way.</p>
<p>The solution to this problem may be “variant-proof” vaccines, also known as “universal” COVID vaccines. These are vaccines which work across different variants, rather than being targeted to a specific variant. These are in development and could be a proactive way to prevent new variants from taking hold.</p>
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<h2>Variant-specific vaccines could take too long to roll out</h2>
<p>Scientists have little doubt vaccination with an Omicron-specific vaccine will provide enhanced immunity to Omicron.</p>
<p>Approvals of these new vaccines should be comparatively rapid because they’re similar to previously approved vaccines, though some additional data on safety and efficacy will be required.</p>
<p>However, the question remains as to whether the rollout of these new vaccines would necessarily be useful to Australian society.</p>
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Read more:
<a href="https://theconversation.com/a-single-vaccine-to-beat-all-coronaviruses-sounds-impossible-but-scientists-are-already-working-on-one-156373">A single vaccine to beat all coronaviruses sounds impossible. But scientists are already working on one</a>
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<p>Following the approval of COVID vaccines in Australia, it took <a href="https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines/numbers-statistics">nine months to vaccinate 70% of the adult population</a>. In contrast, Omicron cases in Australia peaked in less than two months.</p>
<p>Although there are <a href="https://djpr.vic.gov.au/about-us/news/victoria-to-become-home-of-mrna-vaccine-manufacturing">plans to develop local manufacturing facilities by 2024</a>, Australia doesn’t yet have the capacity to mass produce mRNA vaccines (like Pfizer’s and Moderna’s). So, we can expect the rollout of these vaccines to begin significantly later here than in other countries.</p>
<p>Reactively relying on developing variant-specific vaccines, even under idealised production and distribution systems, would always leave Australia vulnerable to disruptive waves of infection and pose ongoing challenges to health strategies. </p>
<p>Waves of new variants would engulf the population faster than variant-specific vaccines could ever be deployed.</p>
<h2>Mass infection isn’t likely to protect against future variants</h2>
<p>Health officials predict <a href="https://www.theguardian.com/australia-news/2022/jan/03/all-of-us-are-going-to-be-exposed-to-omicron-queensland-chief-health-officer-warns">almost all Australians</a> will soon be exposed to Omicron.</p>
<p>This has left many wondering if mass exposure could finally provide Australians with the antibody protection required for the fabled “herd immunity”, making the need for future variant-specific vaccines unnecessary.</p>
<p>A <a href="https://www.ahri.org/wp-content/uploads/2021/12/MEDRXIV-2021-268439v1-Sigal_corr.pdf">small-scale pre-print study</a>, yet to be reviewed by other scientists, suggests infection with Omicron did produce some antibodies that could neutralise Delta, but only around a quarter the magnitude of those produced against the infecting variant.</p>
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<p>Whether these antibodies would be sufficient to protect against the infection from the Delta or other variants, remains to be established.</p>
<p>Most antibodies induced by vaccination and natural infection predominantly target regions of the virus that can easily mutate.</p>
<p>It’s plausible the next variants that emerge could be even more different in this region than Delta or Omicron. This means it could evade current antibody responses induced by infection, or by vaccines specific for either the original virus or the Omicron variant.</p>
<p>So it’s likely mass infection with Omicron won’t protect us from catching future variants.</p>
<h2>Here’s where a variant-proof vaccine comes in</h2>
<p><a href="https://www.abc.net.au/news/2021-12-27/covid-19-variant-proof-universal-vaccine-sars-cov-2/100724488">Several teams around Australia</a> and the world are currently working on efforts to produce “universal” COVID vaccines, including our own research team at the Garvan Institute.</p>
<p>These are vaccines which generate antibodies to regions of the virus that cannot be easily mutated. </p>
<p>The goal of using such vaccines across the population is to protect us not just against current variants of the virus, but also against future variants.</p>
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<p>Unlike the current reactive strategy of generating variant-specific vaccines following the emergence of a new invasive threat, a universal vaccine could be used to prevent a new variant from ever taking hold.</p>
<p>Australia should aim to produce such vaccines locally, so we could avoid the current supply and distribution delays.</p>
<p>As Australia continues to “ride the Omicron wave”, we can only wonder what challenges the next variant will pose for us.</p><img src="https://counter.theconversation.com/content/175137/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Deborah Burnett receives funding from the Australian National Health and Medical Research Council (NHMRC).
Deborah is current working on efforts to develop a "Universal" COVID-19 variant-proof vaccine.
</span></em></p>Variant-specific vaccines would undoubtedly increase immunity. But waves of new variants would engulf the population faster than these vaccines could ever be deployed.Deborah Burnett, Research Officer, Garvan Institute; Senior Lecturer, UNSW., Garvan InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1747032022-01-21T13:42:45Z2022-01-21T13:42:45ZAlpha then delta and now omicron – 6 questions answered as COVID-19 cases once again surge across the globe<figure><img src="https://images.theconversation.com/files/440917/original/file-20220114-16-yxousj.jpg?ixlib=rb-1.1.0&rect=468%2C100%2C10694%2C4318&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The list of SARS-CoV-2 variants – each with its own unique qualities that give it an edge – just keeps growing.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/alpha-beta-gamma-delta-omicron-covid-variant-royalty-free-image/1361940125?adppopup=true">Matt Anderson Photography/Moment via Getty Images</a></span></figcaption></figure><p><em>Editor’s note: The <a href="https://www.cdc.gov/coronavirus/2019-ncov/variants/omicron-variant.html">omicron variant</a> of SARS-CoV-2, the virus that causes COVID-19, has fueled a <a href="https://www.cnbc.com/2022/01/12/who-says-omicron-cases-are-off-the-charts-as-global-infections-set-new-records.html">rapid surge in cases globally</a>. We asked a team of virologists and immunologists from the University of Colorado Boulder to weigh in on some of the pressing questions that people are asking about the new variant.</em></p>
<h2>How is omicron different from previous variants?</h2>
<p>There are two key differences between omicron and previous variants of the SARS-CoV-2 virus that emerged in late 2019. Early data suggests that <a href="https://doi.org/10.1101/2022.01.11.22269045">omicron cases are milder</a> than infections caused by the delta variant. On the flip side, omicron is far more transmissible – meaning it spreads easier – than previous variants. It can be confusing to think about the overall effects of a milder virus that is also far more infectious.</p>
<p>When the delta variant became dominant and displaced alpha in the summer of 2021, it managed to do so because it was <a href="https://asm.org/Articles/2021/July/How-Dangerous-is-the-Delta-Variant-B-1-617-2">between 40% and 60% more transmissible</a>. Now, the omicron variant is even <a href="https://www.npr.org/sections/goatsandsoda/2021/12/15/1064597592/a-tantalizing-clue-to-why-omicron-is-spreading-so-quickly">more transmissible than delta</a>.</p>
<p>It’s difficult to put numbers around how intrinsically more transmissible one variant is than another, because human behaviors and vaccination percentages are constantly in flux. Those factors, together with transmissibility, affect how a virus fares in a population. </p>
<p>In comparison with the original strain of SARS-CoV-2, omicron contains <a href="https://covariants.org/variants/21K.Omicron">72 mutations</a> throughout its genome. Some of these mutations account for the complex new features that characterize this variant. Half of those changes are in the spike protein, the critical surface protein that enables the virus to latch on and infect cells. It is also the key virus feature that is recognized by the human immune system. </p>
<h2>Why is omicron spreading so quickly?</h2>
<p>Initial studies suggest that omicron is more effective at reproducing in the upper airways, including <a href="https://doi.org/10.1101/2021.12.31.474653">the nose</a>, <a href="https://doi.org/10.1101/2021.12.22.21268246">throat</a> and <a href="https://doi.org/10.1038/s41591-021-01296-8">mouth</a>, than earlier variants, making it more similar to a common cold virus. If data from these preliminary studies holds up, then it may help explain omicron’s high transmissibility: Viruses replicating in the upper airways <a href="https://www.nytimes.com/2021/12/31/health/covid-omicron-lung-cells.html">may spread more easily</a>, although the reasons for this are not completely understood.</p>
<p>In addition, omicron is often able to <a href="https://doi.org/10.1038/s41586-021-04385-3">evade existing immunity</a> long enough to start an infection, cause symptoms and transmit onward to the next person. This explains why reinfections and vaccine <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/effectiveness/why-measure-effectiveness/breakthrough-cases.html">breakthrough infections</a> seem to be more common with omicron.</p>
<p>Those properties, and the timing of this variant emerging during the holiday season, resulted in the extraordinary surge in COVID-19 infections in the U.S. Add in wintertime – which brought people indoors – along with <a href="https://www.scientificamerican.com/article/how-we-can-deal-with-pandemic-fatigue/">pandemic fatigue</a>, and you have the perfect storm for rapid transmission. </p>
<p>The good news is that vaccination and vaccine boosters nevertheless <a href="https://www.research.ed.ac.uk/en/publications/severity-of-omicron-variant-of-concern-and-vaccine-effectiveness-">provide good protection</a> against severe disease and hospitalization. But given the current number of cases, that still means a lot of illnesses, hospitalizations and deaths in the weeks to come. </p>
<figure class="align-center ">
<img alt="A computer-generated image of the omicron variant." src="https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441625/original/file-20220119-17-16kkmdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Omicron contains a large number of mutations and is much more transmissible than earlier variants of the SARS-CoV-2 virus.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/omicron-variant-of-coronavirus-or-covid-19-a-royalty-free-image/1359621511?adppopup=true">Uma Shankar sharma/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Could omicron move the population closer to herd immunity?</h2>
<p><a href="https://theconversation.com/what-is-herd-immunity-a-public-health-expert-and-a-medical-laboratory-scientist-explain-170520">Herd immunity</a> occurs when enough people have immunity to a virus that it no longer spreads well. It is only possible when two conditions are met. First, a large fraction of the population must be vaccinated or recovered from prior infection. Second, vaccination or prior infection must confer enough immunity to block or slow future infections. Will vaccination campaigns, combined with widespread omicron infection, be enough to bring herd immunity?</p>
<p>Three issues complicate the hope of achieving a long-term herd immunity after omicron. The first is that immunity naturally wanes over time, regardless of whether it comes from a vaccine or prior infection. It is not yet clear how long after infection or vaccination immunity to this virus lasts, since SARS-CoV-2 has been infecting humans for only two years. Eventually, controlled studies will be able to determine this.</p>
<p>Second, children younger than age 5 are not yet eligible for COVID-19 vaccines, and new susceptible children are born every day. So, until all age groups are eligible for vaccination, there will likely be ongoing transmission in kids. </p>
<p>And third, we can’t rule out that new variants could escape existing immunity. As <a href="https://doi.org/10.1101/2022.01.05.22268782">omicron has shown</a>, infection with one variant doesn’t guarantee protection against infection by future variants. </p>
<p>Together, these three factors suggest that even if a large enough fraction of the population recovers from omicron, long-term herd immunity is unlikely. These are the same reasons that humans never achieve long-lasting herd immunity to influenza and have to get a new flu vaccine each year.</p>
<p>It’s important to remember that, with all variants to date, most of the people who are hospitalized for COVID-19 <a href="https://coronavirus.health.ny.gov/covid-19-breakthrough-data">are unvaccinated</a>. This shows that vaccines are an effective tool for reducing disease severity and can be beneficial even against new variants. </p>
<h2>Where do new variants like omicron come from?</h2>
<p>When viruses make more copies of themselves inside of human cells, they make mistakes in that process – mutations – that alter their genetic code. Most of these mutations will not be beneficial to the virus. However, in some instances, a virus hits on a jackpot of one or more beneficial mutations that fuel its spread through a population. The alpha variant possessed some mutations in the spike protein that made it <a href="https://doi.org/10.7554/eLife.69091">easier for viruses to infect cells</a>. The delta variant had additional mutations that <a href="https://www.nature.com/articles/d41586-021-02275-2">improved viral spread</a>. Omicron, with its staggering number of mutations, is a true oddity. It’s rare for a coronavirus to rapidly accumulate so many mutations in its genome. </p>
<p>The origins of omicron are still poorly understood. One prevailing theory is that an immunocompromised person was infected with a coronavirus for an <a href="https://doi.org/10.1056/NEJMc2031364">extended period of time</a>, leading to <a href="https://doi.org/10.1016/j.chom.2022.01.005">accelerated viral evolution</a>. <a href="https://www.statnews.com/2021/12/02/some-experts-suggest-omicron-variant-may-have-evolved-in-an-animal-host/">Another theory</a> speculates that omicron could have evolved in another animal species and then reinfected humans. Alternatively, omicron could have evolved gradually in a location with poor <a href="https://theconversation.com/from-delta-to-omicron-heres-how-scientists-know-which-coronavirus-variants-are-circulating-in-the-us-173971">sequencing surveillance</a>. There is still much more that needs to be understood about the factors that led to the emergence of this highly mutated variant.</p>
<h2>Could omicron mutate to become more deadly?</h2>
<p>The variants that have risen to prominence have done so because they contain advantageous mutations for the coronavirus. We are essentially witnessing Darwinian evolution – survival of the fittest – in real time. Variants with beneficial mutations, such as those providing escape from antibodies or shorter incubation periods, are rapidly displacing their less fit predecessors. </p>
<p>The most important thing to remember about virus evolution is that natural selection favors variants that spread better than other variants. The great news is that more pathogenic – or dangerous – variants are less likely to spread well. This is because individuals who feel particularly sick tend to naturally self-isolate, reducing the virus’s chance to transmit. </p>
<p>Also good news is that, because infection with one variant <a href="https://doi.org/10.1101/2022.01.05.22268782">provides partial immunity to others</a>, omicron’s rapid spread has brought on delta’s swift decline. </p>
<p>At this point it is expected that all new variants that spread widely – so-called <a href="https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-classifications.html#anchor_1632154493691">variants of concern</a> – will continue to be highly transmissible. </p>
<h2>What about the buzz around ‘deltacron’ and ‘flurona’?</h2>
<p>In early January 2022, researchers in Cyprus reported cases of COVID-19 infections containing <a href="https://www.bloomberg.com/news/articles/2022-01-08/cyprus-finds-covid-19-infections-that-combine-delta-and-omicron">sequences of both omicron and delta</a>, dubbed “deltacron.” However, other scientists are speculating that this is nothing more than a <a href="https://www.independent.co.uk/news/science/covid-omicron-deltacron-variant-lab-b1992996.html">laboratory contaminant</a> – an omicron sample contaminated with delta. While more details are needed, as of now, there is not cause for alarm over this possible hybrid because it has not been commonly observed.</p>
<p>And in recent weeks <a href="https://www.washingtonpost.com/health/2022/01/05/flurona-coronavirus-flu-symptoms/">the term “flurona” has surfaced</a>, referring to an individual who is infected with both influenza virus and a coronavirus at the same time. While rare, such situations do happen, and it’s important that you reduce your risk by receiving both the influenza and COVID-19 vaccines. But it’s important to note that flurona is not a new combination of the flu and coronavirus genomes, making this term a bit of a misnomer.</p><img src="https://counter.theconversation.com/content/174703/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sara Sawyer is a co-founder of Darwin Biosciences. She receives funding from the National Institutes of Health and the Department of Defense.</span></em></p><p class="fine-print"><em><span>Cody Warren receives funding from the National Institutes of Health. </span></em></p><p class="fine-print"><em><span>Arturo Barbachano-Guerrero does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>People are buzzing with questions about the omicron variant and whether it could help usher in herd immunity. A team of virologists deciphers the latest findings.Sara Sawyer, Professor of Molecular, Cellular and Developmental Biology, University of Colorado BoulderArturo Barbachano-Guerrero, Postdoctoral Fellow in Virology, University of Colorado BoulderCody Warren, Postdoctoral Fellow in Virology and Immunology, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1741952022-01-09T13:14:44Z2022-01-09T13:14:44ZOmicron: Vaccines remain the best defence against this COVID-19 variant and others<figure><img src="https://images.theconversation.com/files/439616/original/file-20220106-13-ngc07h.jpg?ixlib=rb-1.1.0&rect=125%2C26%2C5622%2C4136&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The best way to stop new variants from arising is to increase the proportion of vaccinated individuals while maintaining infection prevention measures like wearing masks and social distancing.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 175px; border: none; position: relative; z-index: 1;" allowtransparency="" src="https://narrations.ad-auris.com/widget/the-conversation-canada/omicron--vaccines-remain-the-best-defence-against-this-covid-19-variant-and-others" width="100%" height="400"></iframe>
<p>We have made it through another pandemic winter holiday. Fortunately, COVID-19 fatalities have decreased since the year before, however, the numbers still weren’t ideal. Using Dec. 25 as a reference date, <a href="https://ourworldindata.org/explorers/coronavirus-data-explorer?zoomToSelection=true&time=2020-03-01..latest&facet=none&pickerSort=asc&pickerMetric=location&Metric=Confirmed+deaths&Interval=7-day+rolling+average&Relative+to+Population=true&Align+outbreaks=false&country=USA%7ECAN">the death rate from COVID-19</a> in the United States was 4.27 per million in 2021, compared to 7.48 per million in 2020. In Canada, it was 0.42 per million in 2021, compared to 2.95 per million the previous year — a much more significant decrease. </p>
<p>The difference that vaccination is making becomes clear when comparing the <a href="https://ourworldindata.org/explorers/coronavirus-data-explorer?zoomToSelection=true&time=2020-03-01..latest&facet=none&pickerSort=asc&pickerMetric=location&Metric=People+fully+vaccinated&Interval=7-day+rolling+average&Relative+to+Population=true&Align+outbreaks=false&country=USA%7ECAN">corresponding rates of fully vaccinated people: 61.4 per cent in the U.S. compared to 77.1 per cent in Canada</a>. The higher vaccination rate in Canada corresponds to the more sharply reduced death rate.</p>
<p>As a medical doctor and researcher of COVID-19, I am optimistic about the power of increased vaccination rates in combination with infection prevention practices to fight the pandemic. </p>
<p>Waiting for <a href="https://theconversation.com/5-failings-of-the-great-barrington-declarations-dangerous-plan-for-covid-19-natural-herd-immunity-148975">natural herd immunity</a> will not fix this or save lives. In the U.S., the <a href="https://www.nytimes.com/interactive/2021/us/covid-cases.html">55 million people who have tested positive for COVID-19</a> since the pandemic began represent only about 17 per cent of the roughly 330 million population — nowhere near the <a href="https://theconversation.com/covid-19-may-never-go-away-but-practical-herd-immunity-is-within-reach-162406">level needed for herd immunity</a>. The only ethical means of achieving herd immunity is vaccination.</p>
<h2>Omicron</h2>
<p>Unfortunately, the Omicron variant may have <a href="https://pubmed.ncbi.nlm.nih.gov/34873578/">greater potential to infect people than past variants</a>, and may be more able to infect fully vaccinated and boosted individuals, according to research awaiting peer review. This new form of the virus is a product of its natural evolution. The longer a pandemic lasts, the more changes occur with a virus. </p>
<p>The best way to stop new variants from arising is to increase the proportion of vaccinated individuals while maintaining infection prevention measures, like following recommendations for face masks and social distancing. <a href="https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/fully-vaccinated-people.html#:%7E:text=Evidence%20suggests%20the%20US%20COVID,interrupting%20chains%20of%20transmission.">Vaccinated individuals are less likely to pass on the virus if they do become infected</a>.</p>
<p>Most cases and deaths <a href="https://covid.cdc.gov/covid-data-tracker/#rates-by-vaccine-status">continue to affect unvaccinated individuals</a>. Further sickness and death are largely preventable, just as most of the illness and death in recent months were. Vaccine refusal, in the absence of valid medical reasons, and not adhering to infection prevention measures are largely responsible for the continued hardship of the pandemic. </p>
<h2>Vaccines and variants</h2>
<p>Vaccines remain an effective tool towards ending the pandemic, particularly against Omicron. This is despite research awaiting peer review indicating the new variant may have <a href="https://pubmed.ncbi.nlm.nih.gov/34873578/">greater potential to infect people than past variants</a>, and may be more able to infect fully vaccinated and boosted individuals. </p>
<p>More data is needed to establish how much more or less infectious the Omicron variant is compared to others, but <a href="https://asm.org/Articles/2021/December/How-Ominous-is-the-Omicron-Variant-B-1-1-529">Omicron’s ability to infect vaccinated individuals (albeit less so than unvaccinated individuals) is concerning</a>. That means infection prevention activities, like wearing a mask and social distancing regardless of vaccination status, are still essential. <a href="https://doi.org/10.1038/d41586-021-03614-z">Poor adherence to these measures can be enough to increase cases in a community</a>, even with many vaccinated folks. </p>
<figure class="align-center ">
<img alt="Illustration of a row of coronaviruses in a gradient of colours" src="https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=217&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=217&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=217&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=272&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=272&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439629/original/file-20220106-19-173dcvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=272&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The longer a pandemic lasts, the more changes occur with a virus.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>While vaccines are less protective against becoming infected with Omicron than other variants, <a href="https://directorsblog.nih.gov/2021/12/14/the-latest-on-the-omicron-variant-and-vaccine-protection/">they offer significant protection against developing an infection</a> and <a href="http://doi.org/10.1056/NEJMc2119270">severe illness</a>. </p>
<p>For those who have already had COVID-19 but have not been vaccinated, the evidence available so far suggests that they should still get vaccinated <a href="https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/covid-19/report-49-Omicron/">because past infection did not protect against Omicron</a>. While there are claims that Omicron produces milder illness, one cannot rely on this when infected individuals still face a significant chance of severe disease.</p>
<p>Several months of winter remain, and COVID-19 <a href="https://globalnews.ca/news/8479373/covid-canada-omicron-christmas/">cases are ballooning again</a>. There is reason to believe that the pandemic will get worse before it gets better. </p>
<h2>Pandemic toolkit</h2>
<p>Booster shots are readily available in the U.S. and are increasingly available in Canada. <a href="https://directorsblog.nih.gov/2021/12/14/the-latest-on-the-omicron-variant-and-vaccine-protection/">Boosters have been shown to confer increased protection against the Omicron variant</a>. </p>
<p>It is everyone’s social responsibility to get the booster, with the exception of the very few people who are allergic to vaccine components. Research showed that <a href="http://doi.org/10.1001/jamanetworkopen.2021.22255">being highly allergic to something that is not vaccine-related rarely equates with an expected severe allergic reaction to the vaccine</a>. </p>
<figure class="align-center ">
<img alt="Illustration of a hand holding a syringe pointed at a coronavirus against a background of stopwatches" src="https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=209&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=209&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=209&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=263&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=263&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439630/original/file-20220106-27-1yqmm7w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=263&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Vaccines remain an effective tool towards ending the pandemic, particularly against Omicron.</span>
<span class="attribution"><span class="source">(Pixabay)</span></span>
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<p>I have an allergy to shellfish that has placed me in the hospital when I inadvertently consumed it. Nothing happened to me when receiving any of my three shots of COVID-19 vaccines, and the above research suggests that this would be the case for most people with non-vaccine allergies. </p>
<p>The risks of COVID-19 far outweigh the very small risk of having an allergic reaction to the vaccine. In the unlikely event that you did have an allergic reaction to the vaccine, such reactions are typically mild and readily treated.</p>
<p>The pandemic will get better if we work together. While news of Omicron and implications on vaccine effectiveness are disheartening, more systems are in place to respond to this change and future changes in the pandemic. Pfizer, one of the drug makers of the effective COVID-19 vaccines, <a href="https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-provide-update-omicron-variant">has already announced a readiness to produce vaccines adapted to the changing virus</a>. We can expect other manufacturers to follow suit, ensuring that the therapies needed to meet this challenge are available. </p>
<p>This leaves it up to consumers — us — to do our part in ending the pandemic.</p><img src="https://counter.theconversation.com/content/174195/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julian Daniel Sunday Willett does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Even with a variant like Omicron that may be more transmissible than earlier variants, vaccines remain the most effective tool for protection against COVID-19 and for ending the pandemic.Julian Daniel Sunday Willett, PhD Candidate, Quantitative Life Sciences, McGill UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1740322021-12-19T11:14:36Z2021-12-19T11:14:36ZAnswers from COVID experts: How do you talk to family members who aren’t vaccinated? How can the vaccines be safe if they were developed so quickly? Is natural immunity better than being vaccinated?<figure><img src="https://images.theconversation.com/files/438294/original/file-20211218-23072-19asa4x.JPG?ixlib=rb-1.1.0&rect=4%2C4%2C2991%2C1962&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">With the holiday season approaching, people wait to receive a COVID-19 vaccination in Montréal as the pandemic continues in Canada and around the world. </span> <span class="attribution"><span class="source">THE CANADIAN PRESS/Graham Hughes </span></span></figcaption></figure><p><em>The Conversation Canada and McMaster University recently co-hosted a live event on vaccine hesitancy. Editor-in-Chief Scott White spoke with four researchers from McMaster: Medical doctor, educator and researcher Zain Chagla; immunologist Dawn Bowdish; Manali Mukherjee, an assistant professor in the division of respirology at McMaster’s department of medicine; political scientist Clifton van der Linden, who has been conducting ongoing public opinion surveys on COVID-19. Viewers submitted questions to the panel. This is an edited excerpt from the discussion, but you can watch the entire event in the video below.</em></p>
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<p><strong>Scott White</strong>: How many of you have a vaccine hesitant person in your inner circle? What have you tried to say to them to persuade them that vaccines are safe?</p>
<p><strong>Dawn Bowdish</strong>: All the good practices that I use with strangers, I have a hard time implementing with my own family. I think one of the important parts about vaccine hesitancy is it’s not my facts versus your facts and I have all the right facts and you have all the wrong facts, because people who are vaccine hesitant have lots of information, and there’s no metric to say that makes them feel that my information is better than theirs. So I feel like listening to people’s concerns and being really specific and not making judgment calls about what their concerns might be. Because to be honest, the vaccine hesitancy spectrum is huge. So where I have gone wrong with my own family is doing all the things that you shouldn’t do. I talked more than I listened. I threw scientific facts as opposed to listening to people’s stories and concerns. And I appealed to the authority. “I’ve got a PhD. I’ve been working on this for 20 plus years,” and that was a mistake. And so those are the things I would caution people against when you have your own conversations with your vaccine hesitant family members or friends.</p>
<p><strong>Zain Chagla</strong>: We know from things like smoking cessation where the more times that conversation happens in a nonjudgmental and non-confrontational matter, it often ends up with the right outcome at the end of the day. So again, it’s not a conversation to win to the other side and get someone to the pharmacy that afternoon. It’s a conversation to start another conversation and start another conversation and keep going along those lines.</p>
<p><strong>Scott White</strong>: Cliff, you’ve done a lot of work on taking the public pulse on this. What have you learned on trying to convince someone?</p>
<p><strong>Clifton van der Linden</strong>: Certainly, no matter how we model the public opinion data coming in on attitudes towards COVID-19, when it comes to vaccine hesitancy, trust is really the major factor. I think we are in an era where there’s a real sense of anti-intellectualism that’s being cultivated in certain corners of the internet. I think the social media discourse has a huge role to play in the way that trust has eroded as a society. But there are factors in the way that government has conducted itself. There are factors in the bad faith in which certain public actors have conducted themselves. And so there are lots of reasons for mistrust at an institutional level. So I do think that trying to ground conversations with people we love in that framework of trust, knowing that we are concerned about them, that we’re approaching them not because we want to be right but because the consequences of them being wrong are so dire for themselves and for our families and loved ones.</p>
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<img alt="" src="https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="source" href="https://theconversation.com/ca/topics/vaccine-confidence-in-canada-107061">Click here for more articles in our series about vaccine confidence.</a></span>
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<h2>Why are there such strong reactions against vaccines?</h2>
<p><strong>Scott White</strong>: One thing that’s always puzzled me is that there seems to be this really rabid reaction against vaccines, but not other medical procedures like surgery, which is far more invasive, or taking medicine. What is it about vaccines that really seems to cause this hesitancy or resistance?</p>
<p><strong>Dawn Bowdish</strong>: My belief is that it’s partly because it’s a needle and partly because there’s this big mystery about how the immune system works and how it (the vaccine) could be so powerful. The active ingredients in our current vaccines is like 10 micrograms. If you look in your medicine cabinet at your Tylenol, your Advil or whatever, you’ll see that we work in milligrams. But 10 micrograms, a thousand times less, has this incredible powerful effect to be able to create a whole immune response. The amount of stuff that’s in the vaccine is negligible. It’s nothing. But this incredibly powerful immune event, I think is a little bit humbling in some ways.</p>
<p><strong>Clifton van der Linden</strong>: I think that especially in the last five or six years, we have been flooded with discussions of fake news, misinformation, disinformation. I mean, we are told not to trust what we hear from government, depending on who’s running government. The idea that you can trust one day and then not trust the next when there’s a change of party, it leaves people in the state of constant cynicism about the good faith I think particularly of elected officials, but also of government institutions in general. I think there’s a difference in Canada compared to countries like the U.S., where in Canada we do see that the public tends not to trust elected officials, but we still do have a lot of trust in our public health institutions in Canada.</p>
<h2>The safety of vaccines that were developed so quickly</h2>
<p><strong>Scott White</strong>: At <em>The Conversation</em>, we’ve been running <a href="https://theconversation.com/ca/topics/vaccine-confidence-in-canada-107061">a series of articles about vaccine confidence and vaccine hesitancy</a> and have been inviting questions from the public. And sort of one of the recurring questions that we get is that people seem to have trouble wrapping their head around the fact that the COVID vaccines have been developed so quickly and that scientists don’t know the long-term effects.</p>
<p><strong>Dawn Bowdish</strong>: The apparent speed was based on decades of fundamental research. I love this as a story because often times as a university academic, the general public thinks we waste time working on things that are fundamentally unimportant. In fact, we did have mRNA based vaccines in the pipeline for many different infections. One of the beauties of the mRNA technology is that it’s fairly easy to alter. Many of the features of vaccination – the dosing intervals, the amount of doses, how we de develop things for kids and for adults and older people – are all based on decades and decades of experience.</p>
<h2>Pregnancy and vaccines</h2>
<p><strong>Scott White</strong>: We get a lot of questions about the potential impact of vaccines on fertility. Zain, from a medical perspective, what are the dangers of not being vaccinated if you are pregnant?</p>
<p><strong>Zain Chagla</strong>: Look, no one is going to deny that most people do get through their infections and don’t die. I think we know this very well, but it doesn’t say that everyone is safe. We do know that elderly people are much more at risk of complications. We know what people with comorbidities are in much more risk of complications. And we have seen young people, who despite looking great on paper, are sitting in our ICUs ventilated, because again, once this virus gets out of control, once the immune system gets super jacked up, it really can cause chaos. And we sometimes don’t know who is that person that it’s going to be chaotic in and not. Pregnant women, I think we’re recognizing much more are in that risk group now. And then we have seen some fairly sick pregnant women. They’re physiologically unwell. They’re obviously carrying a baby. The concerns of having severe COVID not only in the mother, but in the baby, are also a major issue. Unfortunately, we’ve had to deliver babies prematurely for the fact that it would spare the mother their lives more and then make their mother’s oxygenation better.</p>
<p><strong>Dawn Bowdish</strong>: We don’t have a single example of a vaccine leading to long term fertility issues or leading to, I don’t even know what people are envisioning with the context of fertility, but the immune system attacking your ovaries or whatever. And in fact, all those mythologies I think were incredibly clever by the anti-vax group. Because if you’re a parent, what more do you want than grandchildren? And so what is going to trigger your emotional response and your desire to wait and to see more than that threat?</p>
<h2>What is long COVID?</h2>
<p><strong>Scott White</strong>: Manali, you’ve not only researched long COVID, but you’re dealing with it personally. I’m not sure that people fully understand the term and the impact that it can have on your life. So can you tell us about that? And then also speak about the best way to avoid it.</p>
<p><strong>Manali Mukherjee</strong>: A considerable proportion of people who have been infected with COVID-19, irrespective of how severe they were, whether they were in the hospital or whether they recover at home, they continue to have symptoms or actually develop new symptoms long after they have so-called recovered. So the public health gives you that call and tells you, “You know, you have recovered. If you’re feeling fine, go back to work.” But there are a number of people who still feel sick, who have lingering symptoms. These symptoms can range anywhere from chronic fatigue, sense of smell not being there, completely being distorted, having diffused pain, and of course all these can lead to anxiety, palpitations and cognitive impairment. So it’s a constellation of symptoms that’s kind of lingering. And none of these symptoms can be attributed to a clinical diagnosis that they either had before getting COVID. We are trying to look at what might be the reason behind it. I have reasons to believe that it’s deep seated within the immune system. I think that after having COVID, the immune system is still so hyper and it still thinks that the virus is possibly hiding somewhere or there is something still going on and the symptoms are a clinical manifestation of that misunderstanding that the immune system has. So that’s what we are trying to right now unravel and understand and makes sense.</p>
<p><strong>Scott White</strong>: Who’s more susceptible to long COVID? Is it younger people? Older people? Do we know?</p>
<p><strong>Manali Mukherjee</strong>: In my study, I’m seeing people from all age groups, all ethnicities coming in. Even asymptomatic people, people who have the infection, PCR positive test was in asymptomatic. Now they’re having symptoms. So really, we don’t know who’s going to get affected, why they’ll be affected. And worse, we just don’t know when this will stop or whether it will. What worries me right now is we don’t know much right now about the long COVID cases that we have from the original virus, the Wuhan virus to the alpha, beta, delta strains, how long COVID symptoms vary. And now the omicron has come in where we don’t know how it’s really going to be affecting our immune system given that it seems to have a higher transmissibility. And having been said, despite having a milder load, we don’t know how it’s going to really affect those with a longer COVID kind of situation. Will it affect more people with lingering, longer persisting symptoms than actually having a more severe acute infection phase? We don’t know. If you are vaccinated, there is data out there that it kind of reduces your long COVID symptoms. So if you are vaccinated and then still you get omicron, the logic tells me that your immune system might be a better streamlined, the way Dawn said, to handle that infection in a better mode as to not confuse it and make it more rowdier and lead to those lingering long COVID symptoms. So that is again another thing that tells me that vaccination and taking the boosters might actually be in our benefit as a society and community going towards natural immunity or herd immunity.</p>
<h2>Natural immunity vs. vaccine immunity</h2>
<p><strong>Scott White</strong>: There’s been a lot of discussion about herd immunity and on social media, instant experts say natural immunity is better than being vaccinated. Dawn, tell us about herd immunity and natural immunity versus vaccinated – especially as we’re now dealing with the omicron variant.</p>
<p><strong>Dawn Bowdish</strong>: Well, I mean, Manali just gave you an example of natural immunity, right? Long COVID is a natural immune response in some people. I don’t think there’s anything unnatural about a vaccine response. It’s giving your immune system the opportunity to work without distraction, right? So when you get infected with a virus, the virus doesn’t just say, “Oh, whoa. It was me. The immune system’s coming to get me.” It’s destroying tissues. The immune system in many cases is misdirecting and attacking those tissues. So some of the tissue damage we see is mediated by natural immunity, because it gets confused where there’s tissue damage in the context of infections. So natural immunity works sometimes, but vaccine immunity is natural immunity. It’s immunity working without distraction, letting the immune system do its thing without having this virus that’s fighting back and trying to thwart it. The thing about herd immunity is, let’s go back to a time before we had vaccines, antibiotics and doctors. One in three to one in five children died. There were more miscarriages, spontaneous abortions and babies born with severe complications because having an infection during pregnancy is problematic. Sure, if you were one of the lucky ones to survived your first birthday, you might have some level of protection until you got older or until you’ve had some immune compromising event or other illness. So a herd immune system gives a small percentage of the population a little bit of time to be protected from that. But as soon as a new baby’s born, a new pregnancy started, that susceptibility happens all over again. So the idea that we would just let a new virus run rampant in a population and take those risks to the young, the old, the random healthy adults is just cruel from my perspective. Really cruel. The best way for us to reach herd immunity is to get us all vaccinated.</p>
<p><strong>Zain Chagla</strong>: Right now our health-care system is burned to a crisp. We can’t deal with our current caseloads because we have complex patients coming in every day. We have ICU beds that are still allotted for COVID patients and we have health-care workers that are burnt out and have left the profession and are not coming back. So there is a lot of worry in the coming weeks and months as this circulates, that we’re going to see health systems overload. We’re going to see a lot of people test positive regardless of the vaccine status. And we’re going to see a lot of isolation and complications from that. The good news out of all of this though, is boosters do seem to really change the dynamic of vaccines and offer higher level of protection. We’re getting better data by the day that really is suggesting this. And so, I think there is work being done right now across the country, in particular Ontario, to make sure people do have access to a booster shot when their time comes.</p>
<h2>A lack of trust in expertise</h2>
<p><strong>Scott White</strong>: Some people don’t trust government. They don’t trust pharmaceutical companies. And although they may trust their personal doctor, they don’t trust intellectuals and they don’t trust people at universities. Why is that Cliff?</p>
<p><strong>Clifton van der Linden</strong>: We’ve seen a rise in populism throughout western democracies. And along with that rising populism, we’ve seen an unprecedented strain of anti-intellectualism, rejection of science in ways that we have not seen in the post-war era. So I think this is tied up in ideological convictions of partisanship, but really also in polarization. It’s no longer acceptable to have reasonable disagreements. I do think that the structure of public discourse on social media has conditioned us in such a way as to stick to our guns no matter what, to really not be permitted to make mistakes or reverse our judgment even if that means rejecting the decades of scientific research that have been undertaken. And then also looking for signals that substantiate that existing bias that one has.</p>
<h2>Isolation is not a protection strategy</h2>
<p><strong>Scott White</strong>: We had a question sent in to us about someone who’s homeschooled their kids and therefore they believe that that minimizes exposure to others. Again, you hear this from some people. “I don’t get out much” or “I don’t work in an office” or “I work outside, so therefore I don’t really need to be vaccinated.” How would you respond to someone who said something like that?</p>
<p><strong>Zain Chagla</strong>: I have seen people who have tried their best to isolate people that were homebound, but are reliant on certain people to be in their environment for their care that have gotten COVID. So number one, reducing your contacts and staying at home will reduce your risk, but it’s fallible. There are ways that people can get through it. People have to still go to the grocery store, people eventually have to see family, people have to get in public transit, and other ways that people came at exposed. Number two, there is this overlying belief that COVID-19 is somehow going to disappear from the face of this earth. And it’s not, right? This is going to be one of our endemic viruses. It’s not there yet. We’re still seeing epidemic spread, but this is going to be there today, it’s going to be there tomorrow, it’s going to be there the next day. And so, unless you plan on you and your family living a lifestyle where you’re going to be homeschooled and staying at home for the foreseeable decade or two, you’re going to encounter COVID at some point or another. And again, the best thing you can do for your body is have immunity to the virus and have a head start so that when you are encountering this virus, you can deal with it.</p>
<h2>Can minds be changed at this stage?</h2>
<p><strong>Scott White</strong>: Cliff, as someone who’s taking the pulse of the public all the time, do you think that at this stage, almost a year to when the vaccines have been available, is there anything that can be done to convince those who haven’t been vaccinated to actually make that decision now?</p>
<p><strong>Clifton van der Linden</strong>: I think there are some difficult decisions that policy makers have to engage with around this. We’ve seen the efficacy of mandatory vaccinations in certain sectors that has led to people who don’t want to be vaccinated, but nevertheless have made the decision to be vaccinated based on the policies that were put in place. That’s not something that should be done lightly. I think there are reasonable concerns about the government imposing mandatory measures, but there are choices to be made about the collective health of the population. And I will say that what we see in the data of public opinion is that the people who are reluctant to get vaccinated are not a homogenous group. There are different clusters within that group who have different motivations, ideas. They’re basing their decisions on different information and intuition and feelings. And they have different interactions with the public health-care system. But in terms of what we can do, I think it goes back to almost the beginning of the conversation and the really insightful things that my colleagues on this panel have spoken about, which is certainly any frame or any conversation that seeks to patronize or belittle the reasons that people have for not getting vaccinated is probably not going to end up being a successful path to convincing them otherwise. And these are not by and large people who haven’t read anything or who haven’t looked up information in the vaccine or who haven’t taken this very seriously. They do take it seriously. They read a lot about it. But there have been decades of concerted efforts to undermine science when it conflicts with certain interests. Look at the science on climate change for example. This is not something that’s new that has eroded confidence in science in general. We have also consistently underfunded STEM in our public education systems. And that lack of funding has led to an inability to discern authentic information from disinformation and misinformation in the broader public. So it’s almost a perfect storm of institutional and political failings that has led us at this point. I don’t fault individuals by and large. I think we have to think about the system that has led us to the place in which we are now.</p><img src="https://counter.theconversation.com/content/174032/count.gif" alt="The Conversation" width="1" height="1" />
A panel of experts answer questions about vaccines, omicron and other COVID-related issues in a discussion with The Conversation.Scott White, CEO | Editor-in-Chief, The Conversation CanadaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1733242021-12-09T16:53:37Z2021-12-09T16:53:37ZChildren ages 5 to 11 are getting COVID-19 vaccinations: What this might mean for the holidays and the Omicron variant<figure><img src="https://images.theconversation.com/files/436447/original/file-20211208-140109-sdogbt.png?ixlib=rb-1.1.0&rect=0%2C0%2C973%2C785&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Young children are rolling up their sleeves to get vaccinated, protecting themselves against COVID-19 and helping to curb the pandemic.</span> <span class="attribution"><span class="source">(Dasantila Golemi-Kotra)</span>, <span class="license">Author provided</span></span></figcaption></figure><p><a href="https://www.thestar.com/news/canada/2021/11/18/health-canada-is-set-to-approve-the-pfizer-covid-vaccine-for-kids-heres-what-you-need-to-know.html">Public Health Canada</a> approved the use of <a href="https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/pfizer-biontech.html">Pfizer/BioNTech</a> mRNA vaccine for children ages five to 11 on Nov. 19. The decision was highly anticipated as parents — including one of the authors — have been waiting to protect school-age children in the face of growing SARS-CoV-2 positive cases and spare them from another interruption of the school year. (Children ages five to 11 represent <a href="https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines/pfizer-biontech-10-mcg-children-5-11-years-age.html">7.5 per cent</a> of all the cases in Canada, with potentially <a href="https://theconversation.com/im-an-infectious-disease-doctor-yes-im-vaccinating-our-5-year-old-against-covid-19-here-is-why-you-should-too-171001">life-threatening consequences</a>.)</p>
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<img alt="" src="https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410911/original/file-20210712-19-geybnm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="source" href="https://theconversation.com/ca/topics/vaccine-confidence-in-canada-107061">Click here for more articles in our series about vaccine confidence.</a></span>
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<p>As soon as the provincial online booking system became available on Nov. 23, Dasantila booked her daughter for an appointment over the weekend, not wanting her to miss any school days. Then she started planning how to offer comfort on the day of the vaccination: her daughter does not like needles — the sight of a needle on TV or in a magazine or even mentioning one makes her cringe, and she instinctively covers her left arm and says she is in pain.</p>
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Read more:
<a href="https://theconversation.com/if-your-child-is-afraid-of-or-refusing-a-medical-procedure-heres-how-to-help-170923">If your child is afraid of — or refusing — a medical procedure, here’s how to help</a>
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<p>The following day, however, she came home and asked whether her vaccination had been booked. When gently informed that it would be on the weekend, she inquired why not sooner? Dasantila was shocked that her little one, who usually had to be coaxed with chocolate to get her shots, was not happy that her vaccination was not booked sooner. Hiding her shock, Dasantila asked why she wanted it sooner, and her daughter said everyone in her class was getting it sooner.</p>
<p>It’s a reminder that children may be stronger than we imagine them to be, and may exceed our expectations. It’s also another reason to thank teachers who have been consistent in their message about the importance of public health measures to protect themselves and others.</p>
<h2>What is the vaccination coverage in Canada?</h2>
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<a href="https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person out-of-frame holds a smartphone camera in the foreground as a girl gets vaccinated" src="https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=431&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=431&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=431&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=542&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=542&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436451/original/file-20211208-25-1us6nae.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=542&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A mother takes a picture of her daughter receiving a COVID-19 vaccine during the second day of vaccination for children aged five to 11 years old in Montréal.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Paul Chiasson</span></span>
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<p>The approval of vaccination for children ages five to 11 years comes at a <a href="https://health-infobase.canada.ca/covid-19/epidemiological-summary-covid-19-cases.html">critical point in the pandemic here in Canada</a>. In <a href="https://www.publichealthontario.ca/-/media/documents/ncov/epi/covid-19-vaccine-uptake-ontario-epi-summary.pdf?la=en">Ontario</a>, where we live, cases are <a href="https://globalnews.ca/news/8404305/ontario-covid-cases-november-26-coronavirus/">slowly creeping up</a> (the <a href="https://health-infobase.canada.ca/covid-19/epidemiological-summary-covid-19-cases.html">positivity rate</a> — the percentage of people tested who get a positive result — is fluctuating around three per cent), and <a href="https://www.ontario.ca/page/covid-19-cases-schools#section-1">outbreaks in the province’s elementary schools</a> are at their <a href="https://www.cbc.ca/news/canada/toronto/covid-19-ontario-dec-8-2021-school-outbreaks-rapid-tests-1.6277720">highest level since the pandemic began</a>.</p>
<p>A slow increase in positive cases was expected as people gather more indoors due to the cold weather, more venues opened to full capacities and travel bans were lifted. But we don’t know at what rate this trend will continue, so public health measures and vaccines are the thread we must hold on to. </p>
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Read more:
<a href="https://theconversation.com/needle-fears-can-cause-covid-19-vaccine-hesitancy-but-these-strategies-can-manage-pain-and-fear-165009">Needle fears can cause COVID-19 vaccine hesitancy, but these strategies can manage pain and fear</a>
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<p>The participation of five-to-11-year-old children in vaccination programs will make 90 per cent of the population eligible to get vaccinated (this age groups accounts for as many as <a href="https://www.statista.com/statistics/444868/canada-resident-population-by-age-group/">three million</a> children). This level of vaccination can make a substantial difference in “making it or breaking it” for the health-care system in Canada, which has been strained and not at a full capacity when it comes to <a href="https://theconversation.com/collateral-damage-the-unmet-health-care-needs-of-non-covid-19-patients-145934">serving non-COVID-19 patients</a>. </p>
<p>Currently, in Canada, <a href="https://health-infobase.canada.ca/covid-19/vaccination-coverage/">76 per cent of the total population is fully vaccinated</a> (86 per cent of people 12 and older). In Ontario, <a href="https://www.publichealthontario.ca/-/media/documents/ncov/epi/covid-19-vaccine-uptake-ontario-epi-summary.pdf?la=en">77 per cent of total population is fully vaccinated</a> (87 per cent of people 12 and older). Partial vaccination coverage (single dose) among children ages five to 11 is 5.8 per cent in <a href="https://health-infobase.canada.ca/covid-19/vaccination-coverage/">Canada</a> and 22 per cent in <a href="https://covid-19.ontario.ca/data">Ontario</a>.</p>
<h2>Where we are heading?</h2>
<p>A study by the Laboratory for Industrial and Applied Mathematics at York University shows that, with the current Ontario level of full vaccination in the population of 12 and older and in the absence of vaccination for children under 12, the COVID-19 attack ratio (defined as the proportion of infected individuals in the population during an outbreak) among kids <a href="https://doi.org/10.1101/2021.09.25.21263542">under age 12 can reach 18 per cent</a> (the study is not yet peer reviewed).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A boy wearing glasses and a mask gets vaccinated by a health-care worker wearing PPE" src="https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436453/original/file-20211208-136652-fayxzx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The approval of vaccination for children ages five to 11 years comes at a critical point in the pandemic.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Ryan Remiorz</span></span>
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<p>This level of infection in this age group can persist even if the social activity of the populations aged 12 and above remains below 75 per cent of the pre-pandemic level. An effective vaccination among kids five to 11 years old, fortunately, can reduce this attack ratio to under 0.2 per cent. </p>
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Read more:
<a href="https://theconversation.com/im-an-infectious-disease-doctor-yes-im-vaccinating-our-5-year-old-against-covid-19-here-is-why-you-should-too-171001">I'm an infectious disease doctor. Yes, I'm vaccinating our 5-year-old against COVID-19. Here is why you should too.</a>
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<p>A recent report by the same group, published in the PHAC modelling group <a href="https://nccid.ca/covid-19-phac-modelling-group/">Weekly Report</a> (October Report) shows that the attack ratio among all kids under 12 can be lowered to below two per cent if half of kids in this age group are fully vaccinated, and to 0.17 per cent with a 90 per cent vaccination rate in this age group. A game changer!</p>
<h2>Omicron and the holidays</h2>
<p>The emergence of Omicron, a variant that is considered to be <a href="https://www.macleans.ca/news/omicron-variant-will-likely-be-worse-than-delta-according-to-early-research/">more transmissible than Delta</a>, adds more urgency to getting younger ones vaccinated to curb circulation in the community and protect those that remain vulnerable even after being fully vaccinated (including the booster shots). Numerous studies show that <a href="https://theconversation.com/covid-19-vaccine-faqs-efficacy-immunity-to-illness-vs-infection-yes-theyre-different-new-variants-and-the-likelihood-of-eradication-154569">vaccines protect against severe cases of COVID-19 disease</a>, and reduce infection and transmission. </p>
<p>So as the holidays approach, encourage and support those who remain on the fence when it comes to the vaccines, and continue to embrace public health measures: face masks, physical distancing, limited gatherings and hand hygiene. The holidays may seem a bit brighter this way!</p>
<p><em>Do you have a question about COVID-19 vaccines? Email us at <a href="mailto:ca-vaccination@theconversation.com">ca-vaccination@theconversation.com</a> and vaccine experts will answer questions in upcoming articles.</em></p><img src="https://counter.theconversation.com/content/173324/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jianhong Wu receives funding from the Natural Sciences and Engineering Research Council of Canada (NSRRC) and from the Canadian Institute of Health Research. NSERC has also joined force with Sanofi Pasteur Canada in funding his Industrial Research Chair program in Vaccine Mathematics, Modelling and Manufacturing.</span></em></p><p class="fine-print"><em><span>Dasantila Golemi-Kotra does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The participation of five-to-11-year-old children in vaccination programs will make 90 per cent of the population eligible to get vaccinated against COVID-19.Dasantila Golemi-Kotra, Professor, Biology, York University, CanadaJianhong Wu, Professor and Canada Research Chair in Industrial and Applied Mathematics, York University, CanadaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1705202021-11-03T12:28:31Z2021-11-03T12:28:31ZWhat is herd immunity? A public health expert and a medical laboratory scientist explain<figure><img src="https://images.theconversation.com/files/429598/original/file-20211101-25-544rr1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7717%2C5140&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Experts estimate that close to 90% of the U.S. population must be vaccinated to reach herd immunity for COVID-19.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-fill-the-santa-monica-pier-as-crowds-gather-on-news-photo/1233207409?adppopup=true">David McNew/AFP via Getty Images</a></span></figcaption></figure><p>The term <a href="https://theconversation.com/why-herd-immunity-may-be-impossible-without-vaccinating-children-against-covid-19-154790">herd immunity</a> means that enough of a population has gained immunity to stifle a pathogen’s spread. You can think of herd immunity as being similar to fire starting in a field: If the field is dry and filled with weeds, the fire will catch and spread quickly. However, if the field is well-maintained with watering and trimming, the fire will fizzle out. Future embers that might land there will be far less likely to ignite.</p>
<p>The embers are much like SARS-CoV-2, the coronavirus that causes COVID-19. </p>
<p>Herd immunity can theoretically be achieved <a href="https://doi.org/10.1001/jama.2020.20895">either through infection and recovery or by vaccination</a>. The danger of trying to achieve herd immunity through infection is that many people will die or be forced to live with post-recovery disabilities. Moreover, research has shown that the immune response resulting from infection does not always provide <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7044e1.htm">strong enough long-term protection against COVID-19</a> and <a href="https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-info.html">its evolving strains</a>. Thus, public health experts still recommend vaccination against the coronavirus to achieve the strongest and most reliable protection. </p>
<p>When the COVID-19 pandemic erupted, scientists quickly began to develop vaccines so that populations could develop immunity to <a href="https://doi.org/10.1016/j.immuni.2020.04.012">slow the firelike spread of the coronavirus</a>. In the meantime, nearly all countries mandated or encouraged social distancing, masking and other public health measures.</p>
<p>Unfortunately, the disjointed implementation of these efforts, coupled with large-scale surges and the <a href="https://theconversation.com/delta-variant-makes-it-even-more-important-to-get-a-covid-19-vaccine-even-if-youve-already-had-the-coronavirus-164203">emergence of the highly transmissible delta variant</a>, has forced public health experts to recalculate what it would take to reach “herd immunity” for COVID-19.</p>
<h2>Why herd immunity matters</h2>
<p>Prior experience with respiratory pathogens that were comparable to the new coronavirus allowed public health experts to make educated estimates of what would be needed to reach the lower threshold of herd immunity for COVID-19. Initially they believed that around 70% of the population would need to be vaccinated to <a href="https://www.ama-assn.org/delivering-care/public-health/what-doctors-wish-patients-knew-about-covid-19-herd-immunity">effectively slow or stop the spread of SARS-CoV-2</a>. </p>
<p>But with <a href="https://theconversation.com/delta-variant-makes-it-even-more-important-to-get-a-covid-19-vaccine-even-if-youve-already-had-the-coronavirus-164203">the delta variant</a> continuing to spread rapidly around the world, experts revised that estimate. Now, epidemiologists and other public health officials estimate that closer to 90% of the U.S. population would need to be vaccinated to <a href="https://www.healthline.com/health-news/how-delta-variant-has-affected-our-ability-to-reach-herd-immunity#When-might-the-U.S.-reach-herd-immunity-through-vaccinations?">reach herd immunity</a> for COVID-19. </p>
<p>Viruses like <a href="https://www.cdc.gov/polio/what-is-polio/polio-us.html">those that cause polio</a> and <a href="https://doi.org/10.1177/0033354919826558">measles required decades of education</a> and vaccination programs to achieve herd immunity and to ultimately eliminate them in the U.S. But given that new U.S. cases of COVID-19 <a href="https://covid.cdc.gov/covid-data-tracker/#trends_dailycases">continue to number in the tens of thousands</a> daily, it’s become clear that <a href="https://www.nature.com/articles/d41586-021-00396-2">COVID-19 is going to stick around</a>.</p>
<p>[<em>Research into coronavirus and other news from science</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-corona-research">Subscribe to The Conversation’s new science newsletter</a>.]</p>
<p>There are several reasons it will take some time to achieve COVID-19 herd immunity. The COVID-19 vaccines are <a href="https://theconversation.com/the-fda-authorizes-pfizers-covid-19-vaccine-for-children-ages-5-to-11-a-pediatrician-explains-how-the-drug-was-tested-for-safety-and-efficacy-169907">currently authorized for some age groups</a> but not others. For perspective, roughly 90% of the U.S. population <a href="https://www.cdc.gov/nchs/fastats/immunize.htm">receives the measles, mumps and rubella vaccine – or MMR</a> – as children, and 93% of the population is vaccinated against polio; both of these have been routine childhood immunizations for decades. Since children make up more than <a href="https://www.census.gov/newsroom/press-kits/2020/population-estimates-detailed.html">20% of U.S. residents</a>, the country likely cannot reach COVID-19 herd immunity without widespread childhood vaccination, even if all eligible adults were vaccinated. </p>
<p>As of Nov. 1, 2021, only 67.8% of the total U.S. population ages 12 and up that are <a href="https://covid.cdc.gov/covid-data-tracker/#vaccinations_vacc-total-admin-rate-total">vaccine-eligible had been fully vaccinated</a>. Experts have attributed this to multiple factors including <a href="https://www.texasmonthly.com/promotion/right-place-right-time-txst/">vaccine hesitancy</a> and the <a href="https://theconversation.com/us-is-split-between-the-vaccinated-and-unvaccinated-and-deaths-and-hospitalizations-reflect-this-divide-164460">politicization of the pandemic</a>. </p>
<p>Of course, no vaccine is perfect. Vaccinated people can have <a href="https://www.cdc.gov/vaccines/covid-19/health-departments/breakthrough-cases.html">breakthrough infections</a>, although the COVID-19 vaccines continue to effectively <a href="https://www.washingtonpost.com/health/2021/09/10/moderna-most-effective-covid-vaccine-studies/">reduce the most severe cases of COVID-19</a>. In addition, research suggests that those who experience COVID-19 after vaccination <a href="https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/fully-vaccinated-people.html#:%7E:text=Vaccinated%20people%20can%20still%20become,the%20virus%20is%20widespread">may transmit the virus at lower transmission rates</a> than those who are unvaccinated. </p>
<p><em>Read other short accessible explanations of newsworthy subjects written by academics in their areas of expertise for The Conversation U.S.<a href="https://theconversation.com/us/topics/significant-terms-105996">here</a>.</em></p><img src="https://counter.theconversation.com/content/170520/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rodney E. Rohde has received funding from the American Society of Clinical Pathologists (ASCP), American Society for Clinical Laboratory Science (ASCLS), U.S. Department of Labor (OSHA), and other public and private entities/foundations. Dr. Rohde is affiliated with ASCP, ASCLS, ASM, and serves on several scientific advisory boards. See <a href="https://rodneyerohde.wp.txstate.edu/service/">https://rodneyerohde.wp.txstate.edu/service/</a>. </span></em></p><p class="fine-print"><em><span>Ryan McNamara has received/receives funding from the National Cancer Institutes (NCI) and the National Institutes of Allergens and Infectious Diseases (NIAID). Dr. McNamara has served as a contributor for the National Technology Roadmap for Pandemic Responses and Recovery by the Advanced Regenerative Manufacturing Institute. </span></em></p>Vaccination campaigns like the ones that eventually eliminated polio and measles in the United States required decades of education and awareness in order to achieve herd immunity in the U.S. population.Rodney E. Rohde, Professor of Clinical Laboratory Science, Texas State UniversityRyan McNamara, Research Associate of Microbiology and Immunology, University of North Carolina at Chapel HillLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1697322021-10-28T01:03:15Z2021-10-28T01:03:15ZCOVID vaccines for 5 to 11 year olds are inching closer. Here’s what we know so far<figure><img src="https://images.theconversation.com/files/428707/original/file-20211027-25-ei2y7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/child-face-mask-getting-vaccinated-coronavirus-1823718611">Shutterstock</a></span></figcaption></figure><p>Australian children aged five to 11 could begin receiving the Pfizer vaccine <a href="https://www.smh.com.au/politics/federal/children-as-young-as-five-could-start-getting-covid-vaccines-from-the-end-of-november-20211027-p593jc.html">by the end of November</a>, with the nation’s regulator currently reviewing the health and safety data. </p>
<p>Pfizer <a href="https://www.health.gov.au/ministers/the-hon-greg-hunt-mp/media/minister-hunts-press-conference-in-canberra-on-27-october-2021-on-tga-approves-pfizer-booster-shot-roll-out-and-vaccination-shots-prepared-for-5-11-year-olds">submitted a partial application</a> to Australia’s Therapeutic Goods Administration (TGA) this week and will supply the remaining data over the next two weeks. The TGA will then review all the information and make a decision about whether to approve the vaccine for use in this age group. </p>
<p>Barring any issues, <a href="https://www.smh.com.au/politics/federal/children-as-young-as-five-could-start-getting-covid-vaccines-from-the-end-of-november-20211027-p593jc.html">TGA head John Skerritt expects</a> a decision will be made by the end of November. The Australian Technical Advisory Group on Immunisation (ATAGI), will then advise the government on timing of the rollout.</p>
<p>So what does the data say so far on safety and efficacy? And what are the benefits of vaccinating children aged five to 11? </p>
<h2>Why vaccinate children?</h2>
<p>While the risk of severe COVID in children is low, a small proportion of children who are infected will become severely unwell, and some of them will die from the virus. </p>
<p>As Delta case numbers rise, so too will the number of serious cases and fatalities.
In the United States, children represented more than <a href="https://downloads.aap.org/AAP/PDF/AAP%20and%20CHA%20-%20Children%20and%20COVID-19%20State%20Data%20Report%2010.14%20FINAL.pdf">six million (16.4%)</a> of the total COVID reported cases (8,208 cases per 100,000 children). More than 23,582 US children have been hospitalised and 558 children died (0.01% of child COVID cases). </p>
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Read more:
<a href="https://theconversation.com/how-to-talk-to-your-child-about-a-covid-diagnosis-and-share-the-news-with-others-170014">How to talk to your child about a COVID diagnosis ... and share the news with others</a>
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<p>Multi-system inflammatory syndrome in children <a href="https://www.cdc.gov/mis/mis-c.html">(MIS-C)</a> has been reported in children following COVID infection. This can cause multiple parts of the body to become inflamed, including the heart, lungs, eyes, brain, kidneys, skin and gastrointestinal system.</p>
<p>Since May 2020, 5,217 cases of MIS-C have <a href="https://covid.cdc.gov/covid-data-tracker/#mis-national-surveillance">been reported in the United States</a>, with a median patient age of nine years; 46 children have died from the condition.</p>
<p>Thankfully, although MIS-C can be serious, most children who are diagnosed with MIS-C recover with medical care.</p>
<figure class="align-center ">
<img alt="A young girl in a mask hugs her mother." src="https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428935/original/file-20211027-19-qm6sqn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The risk of severe disease in children is low, but it’s still possible.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cute-child-daughter-hugging-mother-on-1718446282">Shutterstock</a></span>
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<p>The long term effects of COVID are still unknown. In adults, even mild infection can cause a range of <a href="https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/coronavirus-long-term-effects/art-20490351">ongoing symptoms of long COVID</a>. These include fatigue, shortness of breath, joint and muscle pain, loss of smell, chest pain and problems with memory, concentration and sleep.</p>
<p><a href="https://www.nature.com/articles/d41586-021-01935-7">Data from the UK</a> found 9.8% of children aged 2–11 years reported at least one long COVID symptom five weeks after, with other research suggesting <a href="https://www1.racgp.org.au/newsgp/clinical/children-s-risk-of-long-covid-substantially-lower">they rarely last</a> more than 12 weeks. </p>
<p>However, data from Russia which is yet to be peer reviewed found one-quarter of children discharged from hospital had symptoms more than <a href="https://www.medrxiv.org/content/10.1101/2021.04.26.21256110v1">five months later</a>. </p>
<p>Even if a small proportion of children have long-term symptoms, this is of concern, and further studies are required. </p>
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Read more:
<a href="https://theconversation.com/do-kids-get-long-covid-and-how-often-a-paediatrician-looks-at-the-data-166277">Do kids get long COVID? And how often? A paediatrician looks at the data</a>
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<p>There are also other factors to consider. With children under 12 completely unvaccinated, these children can potentially spread the virus to older, vulnerable people. </p>
<p><a href="https://www.webmd.com/lung/news/20210121/kids-highly-likely-to-transmit-covid-to-others#1">This may be a particular risk</a> where extended family live together or older relatives care for younger family members. </p>
<h2>Are the vaccines safe for children?</h2>
<p>This week, the US <a href="https://www.health.gov.au/ministers/the-hon-greg-hunt-mp/media/minister-hunts-press-conference-in-canberra-on-27-october-2021-on-tga-approves-pfizer-booster-shot-roll-out-and-vaccination-shots-prepared-for-5-11-year-olds">Food and Drug Administration’s</a> (FDA) independent advisory committee <a href="https://www.theguardian.com/business/2021/oct/26/covid-vaccine-children-pfizer-fda-kids-debate-latest-">recommended Pfizer</a> be made available to children aged 5-11 years. </p>
<p>When approved, children will receive a <a href="https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-announce-positive-topline-results">reduced dose</a> (one-third of the adult dose) and will <a href="https://www.reuters.com/business/healthcare-pharmaceuticals/pfizerbiontech-covid-19-vaccine-shows-907-efficacy-trial-children-2021-10-22/">receive two doses</a>, at the same schedule as adults: approximately three weeks apart.</p>
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<img alt="Masked boy stands outside school, talking to his friends." src="https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=412&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=412&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=412&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=517&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=517&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428939/original/file-20211027-27-n4g1eu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=517&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Children aged 5-11 will received a third of the adult dose.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/schoolage-children-medical-masks-portrait-school-1698885025">Shutterstock</a></span>
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<p>In order for the new vaccines to gain approval for a new use, they must undertake their own trials to show they are safe and effective in that population specifically. </p>
<p>A <a href="https://www.fda.gov/media/153409/download">recent submission to the FDA</a> showed a robust immune response following the vaccine. It also provided a good safety profile, with side effects comparable to those seen in a study of 16-25 year olds.</p>
<p>So far, <a href="https://www.fda.gov/media/153409/download">no cases</a> of myocarditis or pericarditis (inflammation of the heart and around the heart) have occurred among the children aged 5-11 in the three months after their second dose.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-benefits-of-a-covid-vaccine-far-outweigh-the-small-risk-of-treatable-heart-inflammation-163970">The benefits of a COVID vaccine far outweigh the small risk of treatable heart inflammation</a>
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<p>However, as the vaccination is rolled out to larger groups, there is a small risk of <a href="https://www.cnbc.com/2021/10/26/fda-panel-recommends-pfizers-low-dose-covid-vaccine-for-kids-ages-5-to-11.html">myocarditis and pericarditis</a>. </p>
<p>But the benefits of being vaccinated – in preventing severe disease, hospitalisation and death – outweigh the risk of the rare inflammatory heart conditions, as you can see in the data below.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1453428461461118978"}"></div></p>
<p>While the initial studies were not designed to measure efficacy, they showed the vaccine regimen was <a href="https://www.reuters.com/business/healthcare-pharmaceuticals/pfizerbiontech-covid-19-vaccine-shows-907-efficacy-trial-children-2021-10-22/">90.7% effective</a> at preventing COVID infection. </p>
<p>Of the vaccinated children who developed COVID, symptoms tended to be <a href="https://www.statnews.com/2021/10/23/fda-scientists-say-benefits-of-pfizer-covid-19-vaccine-clearly-outweigh-the-risks-for-children-ages-5-to-11/">very mild</a> and didn’t include a fever. Non-vaccinated children generally presented with headaches and fever. </p>
<h2>What about the other vaccines?</h2>
<p>Early data on Moderna, another mRNA based vaccine, found it was safe and induced <a href="https://www.wsj.com/articles/moderna-data-shows-covid-19-vaccine-produced-strong-immune-response-in-6-to-11-year-olds-11635173936">strong antibody</a> responses in 6-11 year olds. Children aged 6-11 were given half the adult Moderna dose, twice, 28 days apart. </p>
<p>As with adults and adolescents, the most common side effects in children aged 6-11 from Moderna were fatigue, headache, fever and pain at injection site; the majority were mild or moderate. </p>
<p>Moderna plans to submit the data to the FDA, European Medicines Agency and other regulators in the near future.</p>
<p>The protein-based vaccine <a href="https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines/about-rollout/vaccine-agreements">Novavax</a>, (currently under evaluaton by the TGA), has plans to evaluate its use in younger children, however the necessary trials are long from completion. So far, <a href="https://www.clinicaltrialsarena.com/news/novavax-paediatric-subjects-trial/">no preliminary data is available</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-novavax-australias-third-covid-vaccine-option-and-when-will-we-get-it-157227">What is Novavax, Australia's third COVID vaccine option? And when will we get it?</a>
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<p>A study evaluating the AstraZeneca vaccine in children was <a href="https://www.abc.net.au/news/2021-04-07/astrazeneca-pauses-vaccine-study-on-kids-blood-clots/100052424">paused</a> due to safety concerns about blood clots and <a href="https://mvec.mcri.edu.au/references/covid-19-vaccination-in-children/">is unlikely to continue</a>. </p>
<h2>Should I vaccinate my children?</h2>
<p>Given the strong safety and efficacy of the vaccines, and the increasing risk of children contracting COVID as the only remaining population of unvaccinated people, the benefits significantly outweigh the risks. </p>
<p>Vaccination will also play an important role in ensuring vulnerable children can continue to participate in social and educational activities with their peers, and reduce their role in spreading the virus. </p>
<p>It’s OK for parents to have questions about the vaccines. If you do, talk to your GP who can listen your concerns and discuss the evidence and how that relates to your circumstances.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-may-need-to-vaccinate-children-as-young-as-5-to-reach-herd-immunity-with-delta-our-modelling-shows-164942">We may need to vaccinate children as young as 5 to reach herd immunity with Delta, our modelling shows</a>
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</em>
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<img src="https://counter.theconversation.com/content/169732/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vasso Apostolopoulos' COVID-19 research has received internal funding from a Victoria University research grant and from philanthropic donations</span></em></p><p class="fine-print"><em><span>Athina (Tina) Soulis, Jack Feehan, and Maja Husaric do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Regulators are currently reviewing the safety and efficacy data of the Pfizer vaccine for five to 11 year olds before deciding whether to approve its use in this age group.Vasso Apostolopoulos, Professor of Immunology and Associate Provost, Research Partnerships, Victoria UniversityAthina (Tina) Soulis, Strategic Advisor, Neuroscience Trials Australia, Florey Institute of Neuroscience and Mental Health, The University of MelbourneJack Feehan, Research Officer - Immunology and Translational Research, Victoria UniversityMaja Husaric, Senior Lecturer; MD, Victoria UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1695612021-10-15T13:51:56Z2021-10-15T13:51:56ZRelaxing restrictions hasn’t made COVID cases spike – but this doesn’t mean herd immunity has arrived<figure><img src="https://images.theconversation.com/files/426702/original/file-20211015-7324-1ymrgu8.jpg?ixlib=rb-1.1.0&rect=66%2C79%2C2773%2C1597&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-pedestrian-crossing-view-above-1199648089">Varavin88/Shutterstock</a></span></figcaption></figure><p>Back in the summer of 2021, the UK government’s pandemic modellers <a href="https://www.gov.uk/government/publications/spi-m-o-summary-of-further-modelling-of-easing-restrictions-roadmap-step-4-on-19-july-2021-7-july-2021">predicted</a> that there would be a significant COVID outbreak in the autumn. Yet so far, this hasn’t happened. Other countries with good COVID vaccine coverage have also seen their cases fall and then stabilise. So is <a href="https://www.who.int/news-room/q-a-detail/herd-immunity-lockdowns-and-covid-19">herd immunity</a> finally arriving?</p>
<p>Reaching a level of immunity across the population that’s sufficient to stop the virus spreading has been a goal since the beginning of the pandemic. Initially it was hoped natural exposure to the virus would get us there. Yet data from <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00183-5/fulltext">Brazil</a>, <a href="https://www.ft.com/content/38f5398a-8588-48a1-86db-3e8050bace51">India</a> and <a href="https://www.medrxiv.org/content/10.1101/2021.10.04.21264540v1">Iran</a> (some of which is in preprint, and so still needs to be formally reviewed) suggests that herd immunity through natural infection wasn’t achieved in these places despite several waves of infection.</p>
<p>But many countries – such as Portugal, Malta, Denmark and Chile – have now managed to fully vaccinate 70% to 80% of their population, including children. As a result, their overall levels of immunity – when counting vaccine-based and naturally acquired immunity – are very high, allowing for the removal of most, if not all, regulations.</p>
<figure class="align-center ">
<img alt="Graph showing high full vaccination rates for countries such as Malta, Denmark and Portugal, lower average rates for the continents of Europe, South America, North America and Asia, and a very low rate for Africa" src="https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425966/original/file-20211012-21-1bjhti2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>When immunity levels are high like this, models suggest there will be a <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7019e3.htm">rapid decline</a> in COVID-19 cases. But while cases have fallen in these countries over the past months, they’ve now plateaued, and in some cases seem to be creeping up again.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph showing the number of COVID cases per million people in the UK, Israel, Malta, Denmark, Portugal and Chile -- with all countries bar Israel showing a slight recent increase" src="https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/426536/original/file-20211014-18-134z9gt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<p>This inability to drive cases down further is probably due to a number of factors. Principally, there’s the <a href="https://theconversation.com/mutating-coronavirus-reaching-herd-immunity-just-got-harder-but-there-is-still-hope-153025">rise of the delta variant</a>, which is more transmissible. This, above all else, has put to rest the hope of quickly getting rid of COVID. The more infectious something is, the <a href="https://theconversation.com/what-is-herd-immunity-and-how-many-people-need-to-be-vaccinated-to-protect-a-community-116355">more people</a> need immunity to it and the stronger that immunity needs to be to stop it spreading.</p>
<p>And while the vaccines available provide exceptionally <a href="https://theconversation.com/covid-vaccines-how-to-make-sense-of-reports-on-their-effectiveness-155921">high protection</a>, it’s not total. Some vaccinated people will still get COVID. There’s also growing evidence that immunity – from vaccination or infection – <a href="https://theconversation.com/covid-vaccine-effects-wane-over-time-but-still-prevent-death-and-severe-illness-167587">fades over time</a>.</p>
<p>Immunity may also be spread unevenly across the population. Outbreaks that are happening right now in the UK are concentrated in those parts of society where susceptibility is still prevalent, such as in schools. Delaying vaccinating schoolchildren has led to severe outbreaks in young people, with cases in Scotland, for example, exceeding any past peaks in these school-age groups.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph showing that reported cases in Scottish schoolchildren spiked higher than ever before in autumn 2021, and are now much more numerous than cases in adults" src="https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=254&fit=crop&dpr=1 600w, https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=254&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=254&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=320&fit=crop&dpr=1 754w, https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=320&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/426671/original/file-20211015-15-2sevgu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=320&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reported COVID-19 cases for schoolchildren and adults in Scotland since the beginning of the pandemic.</span>
<span class="attribution"><span class="source">Adam Kleczkowski</span></span>
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</figure>
<p>These factors explain why cases aren’t being completely driven down. In fact, they are the reason why many modellers predicted that with measures to control the virus removed, we could see a <a href="https://www.telegraph.co.uk/global-health/science-and-disease/doomsday-covid-models-badly-wrong/">massive outbreak</a>. And yet, in many highly vaccinated countries, the numbers are seeming neither to massively explode nor quickly decline. Why?</p>
<p>Well, the current plateauing of cases could be caused by feedback between the perceived risk of COVID and the lifting of protection measures. Despite restrictions having been relaxed, many are <a href="https://www.theguardian.com/world/2021/aug/01/covid-caution-dampens-the-heady-promises-of-freedom-day">still cautious</a> about going out and socialising. Masks, hand washing and social distancing are compulsory in many <a href="https://www.gov.scot/publications/coronavirus-covid-19-public-use-of-face-coverings/">countries and regions</a>, but even where they’re not many people are <a href="https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthandwellbeing/bulletins/coronavirusandthesocialimpactsongreatbritain/8october2021">continuing with them</a>. Use of public transport is still down compared to <a href="https://data.london.gov.uk/dataset/coronavirus-covid-19-mobility-report">pre-pandemic levels</a> and <a href="https://www.theguardian.com/commentisfree/2021/sep/27/employee-pay-cuts-work-from-home">working at home</a> is still <a href="https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthandwellbeing/bulletins/coronavirusandthesocialimpactsongreatbritain/8october2021">prevalent in many places</a>. Some countries have also introduced <a href="https://corona.health.gov.il/en/directives/green-pass-info/">vaccine passports</a>.</p>
<p>These largely voluntary behaviours may be counterbalancing the virus’s ability to defy immunity levels and spread.</p>
<h2>What’s likely to happen next?</h2>
<p>What we’re seeing now may be what the pandemic looks like in the weeks and months to come. Outbreaks may well be limited, with an <a href="https://theconversation.com/why-are-we-seeing-more-covid-cases-in-fully-vaccinated-people-an-expert-explains-166741">increasing proportion of cases</a> in the vaccinated population, simply because almost everybody is already vaccinated. </p>
<p>Superspreading events, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8343549/">like Euro 2020</a>, might temporarily increase cases. Although repeats of large waves from last winter or last summer are unlikely, bringing down case numbers will be challenging. For some countries, like the UK, high levels of infection will probably persist for the foreseeable future.</p>
<p>Looking further forward, three possible <a href="https://www.nature.com/articles/s41586-021-03792-w">future scenarios</a> have been identified. In the first, the world will face returning waves of severe disease with high infection levels. This is possible if immunity starts waning rapidly or if new mutations arise and the virus persists in unvaccinated pockets worldwide.</p>
<p>Many diseases in the pre-vaccination era – like measles, plague or smallpox – exhibited <a href="https://theconversation.com/four-graphs-that-show-how-the-coronavirus-pandemic-could-now-unfold-133979">devastating cycles</a>. Epidemics were characterised by long spells with low infection levels, during which a susceptible population built up as new, non-immune children were born. These periods were followed by catastrophic outbreaks. This process could repeat itself <a href="http://faculty.jsd.claremont.edu/dmcfarlane/bio146mcfarlane/papers/measles%20Bartlett.pdf">two, three or even more times</a>.</p>
<p>A second scenario could see COVID transition to being an epidemic but seasonal disease, like seasonal influenza, which occasionally erupts into pandemics, such as the 1889-90 Russian, <a href="https://www.cdc.gov/flu/pandemic-resources/1918-pandemic-h1n1.html">1918 Spanish</a> or <a href="https://www.cdc.gov/flu/pandemic-resources/2009-h1n1-pandemic.html">2009 swine</a> flu outbreaks. Despite being seen as “normal”, influenza still causes suffering, resulting in a high health burden to society and, in some years, high death rates. Other diseases, like <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2467415/">cholera</a>, also show seasonal patterns.</p>
<p>In the third scenario, we might see the coronavirus evolving towards being less severe, perhaps becoming like the common cold. Of course, new variants could change the picture, but potentially there are now <a href="https://news.sky.com/story/covid-19-delta-is-making-other-coronavirus-variants-extinct-but-what-does-it-mean-for-the-uk-12431343">fewer opportunities</a> for this to happen because delta is so infectious, it is hard for other variants to out-compete it and gain a foothold.</p>
<p>It is too early to say definitively what <a href="https://www.theatlantic.com/science/archive/2021/08/how-we-live-coronavirus-forever/619783/">“living with the virus”</a> will look like, both in the short and long term, given this range of possibilities. However, it seems very unlikely that herd immunity is going to result in the virus ceasing to be a problem.</p>
<p>What’s almost certain is that the pandemic will have a long tail that is <a href="https://www.theatlantic.com/health/archive/2021/06/individualism-still-spoiling-pandemic-response/619133/">massive and uneven</a>, and which is likely to have a disproportionate impact on the <a href="https://www.theatlantic.com/ideas/archive/2021/09/weve-never-protected-the-vulnerable/619981/">vulnerable</a>, those living in <a href="https://www.theatlantic.com/ideas/archive/2021/08/covid-19-global-inequality/619804/">deprived areas</a> and <a href="https://www.rcog.org.uk/en/news/rcog-supports-calls-from-nhs-to-pregnant-women-to-get-vaccinated-against-covid-19/">pregnant women</a>. It’s also clear that vaccination alone <a href="https://www.tes.com/news/dont-over-rely-covid-vaccine-schools-headteachers-warn-ministers">won’t be enough</a> to suppress the virus. Simple restrictions, like masks, <a href="https://corona.health.gov.il/en/directives/green-pass-info/">vaccine passports</a> or frequent testing, will continue to be part of our lives.</p><img src="https://counter.theconversation.com/content/169561/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Kleczkowski receives funding from the UK Research and Innovation and the Scottish Government. </span></em></p>Voluntary modifications to behaviour – such as mask wearing when it’s not mandatory – are probably helping to keep the virus in check.Adam Kleczkowski, Professor of Mathematics and Statistics, University of Strathclyde Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1676012021-09-14T19:08:05Z2021-09-14T19:08:05ZForceful vaccine messages backfire with holdouts – how can it be done better?<figure><img src="https://images.theconversation.com/files/420892/original/file-20210913-21-15zd52e.jpg?ixlib=rb-1.1.0&rect=0%2C44%2C942%2C579&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Protesters gather at Indiana University in June 2021 to demonstrate against mandatory COVID-19 vaccinations for students, staff and faculty. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/protesters-holding-placards-gather-at-indiana-universitys-news-photo/1233384399?adppopup=true">SOPA Images/LightRocket via Getty Images</a></span></figcaption></figure><p>With the <a href="https://theconversation.com/what-does-full-fda-approval-of-a-vaccine-do-if-its-already-authorized-for-emergency-use-165654">FDA approval of the Pfizer-BioNTech vaccine</a> and the <a href="https://www.usatoday.com/story/news/health/2021/08/24/covid-vaccines-mandates-masks-biden-fauci/8250548002/">continued surge of the delta variant</a>, governments across the world have renewed their push to increase the number of vaccinated individuals by persuading the holdouts. On Sept. 9, 2021, <a href="https://www.nytimes.com/2021/09/09/us/politics/biden-vaccine-mandates-transcript.html">President Joe Biden announced</a> sweeping vaccine mandates, expressing frustration at the vaccine holdouts: “We’ve been patient, but our patience is wearing thin. And your refusal has cost all of us.”</p>
<p>As a <a href="https://www.bellisario.psu.edu/people/individual/s.-shyam-sundar">communication scientist</a> who has studied the effects of media and health campaigns for the past 30 years, I worry that a fevered pitch in vaccine messaging may make the holdouts even more resistant. The direct, blunt messages to go get vaccinated that worked on three-quarters of Americans may not work for the remaining one-quarter. If anything, they might backfire.</p>
<p>Research has shown that some health communication techniques work more effectively than others depending on the audience. It’s a lesson that not only policymakers can apply but also members of the media, industry and even parents and relatives.</p>
<p>When it comes to embracing new ideas and practices, research has identified <a href="http://scholar.google.com/scholar_lookup?hl=en&publication_year=2003&author=EM+Rogers&title=Diffusion+of+innovations">five categories of people</a>: innovators, early adopters, early majority, late majority and laggards. With COVID-19 vaccination, it’s come down to the last two, and they are the most resistant to change.</p>
<p>This group of <a href="https://fivethirtyeight.com/features/unvaccinated-america-in-5-charts/">unvaccinated people</a> is substantial in number – there are nearly <a href="https://www.advisory.com/daily-briefing/2021/07/21/unvaccinated">80 million people</a> in the U.S. who are vaccine eligible yet remain unvaccinated – and they are the ones who could help the U.S. achieve herd immunity. But, research suggests that they are also the ones who will take offense at forceful exhortations to <a href="https://www.nytimes.com/2021/08/05/opinion/coronavirus-mask-vaccine-mandates.html">go get vaccinated</a>. </p>
<h2>Strong messaging can backfire</h2>
<p>Public health messaging can and does often influence people – but not always in the intended direction. Back in 1999, I <a href="https://books.google.com/books?id=euwjAAAAMAAJ&pg=PA155&lpg=PA155&dq=STATEMENT+BEFORE+THE+SUBCOMMITTEE+ON+CRIMINAL+JUSTICE,+DRUG+POLICY+AND+HUMAN+RESOURCES+OF+THE+UNITED+STATES+HOUSE+OF+REPRESENTATIVES+BY+S.+SHYAM+SUNDAR,+PH.D.&source=bl&ots=QAAzWaL6o7&sig=ACfU3U2zK6uWRtXCmPnOmiU5n8XSRl3tJA&hl=en&sa=X&ved=2ahUKEwirh66dmbvyAhUjEFkFHTziDREQ6AF6BAgCEAM#v=onepage&q&f=false">testified in the U.S. Congress</a> about how powerful anti-drug messages may be turning adolescents on to drugs rather than off of them. Likewise, the strong language of current vaccine messaging may be evoking resistance rather than compliance. </p>
<p>Consider <a href="https://www.nytimes.com/2021/08/05/opinion/coronavirus-mask-vaccine-mandates.html">this headline</a> from a recent New York Times editorial: “Get Masked. Get Vaccinated. It’s the Only Way Out of This.” This follows 18 months of public-health messaging urging people to stay home, wash hands and maintain social distancing.</p>
<p>They may be well intentioned, but research in health communication shows that such directive messages can be perceived as “high threat,” meaning they threaten the free will of the message receiver by dictating what they should do. They are likely to trigger <a href="https://psycnet.apa.org/record/1967-08061-000">what psychologists call “reactance”</a>. In other words, when individuals sense a threat to their freedom of action, they become motivated to restore that freedom, often by attempting to do the very thing that is prohibited or by refusing to adhere to the recommended behavior. </p>
<p><a href="https://doi.org/10.1080/00913367.2021.1927914">Recent research</a> by my communications colleagues at Penn State shows that even advertisements that include directive slogans such as “No Mask, No Ride” – from Uber – and “Socialize Responsibly to Keep Bars Open” – a Heineken message – can irritate consumers and make them less likely to engage in responsible behaviors.</p>
<p>Reactance to COVID-19 messaging is evident in the form of <a href="https://www.nytimes.com/2021/07/24/world/france-protests-covid-health-pass.html?smid=em-share">widespread protests</a> around the world. Many have gone to the streets and social media, <a href="https://www.malheurenterprise.com/posts/8849/covid-surge-malheur-county-goes-back-to-school-local-health-experts-ask-community-to-vaccinate">with slogans</a> such as “my body, my choice,” “let me call my own shots” and “coercion is not consent.” </p>
<p>These responses demonstrate not simply hesitation to get vaccinated, but rather active resistance to vaccine messaging, reflecting an effort to protect personal agency by asserting one’s freedom of action. </p>
<h2>Flipping the script</h2>
<p>Freedom is a critical concept in the anti-vaccination rhetoric. “Freedom, not force” is the battle cry of the protesters. “If we lose medical freedom, we lose all freedom,” <a href="https://www.nytimes.com/2021/08/22/nyregion/staten-island-covid-vaccine-workers.html">reads a poster</a>. “Choose freedom,” urged Sen. Rand Paul in a <a href="https://www.paul.senate.gov/fox-news-op-ed-sen-rand-paul-mask-mandates-and-lockdowns-petty-tyrants-no-not-again-choose-freedom">recent op-ed</a> expressing his resistance to mask mandates and lockdowns. “We will make our own health choices. We will not show you a passport, we will not wear a mask, we will not be forced into random screening and testing.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Anti-vaccination protester holds a sign and a flag during a rally against COVID-19 vaccines" src="https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420895/original/file-20210913-27-kozdbl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Freedom of choice has been a constant theme throughout the pandemic, whether it be about masking, school and business closures or vaccination.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-anti-vaccination-protester-holds-a-sign-and-a-flag-as-news-photo/1234951009?adppopup=true">Ringo Chiu/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>One way to counter such reactance is by changing the communication strategy. Health communication researchers have found that simple changes to message wording can make a big difference. In <a href="https://doi.org/10.1080/03637750500111815">one study</a> by my Penn State colleagues who study health persuasion, the researchers tested participants’ responses to sensible health behaviors such as flossing: “If you floss already, don’t stop even for a day. And, if you haven’t been flossing, right now is the time to start. … Flossing: It’s easy. Do it because you have to!” Study participants reacted to such messages by expressing their disagreement through anger and by defying the advocated behavior.</p>
<p>But then the researchers reworded the same advocacy to be less threatening, such as: “If you floss already, keep up the good work. And if you haven’t been flossing, now might be a good time to start.” And “Flossing: It’s easy. Why not give it a try?” They found that the participants’ reactance was significantly lower and their message acceptance higher. </p>
<p>In the same way, softening the message and using less dogmatic language could be the key to persuading some of the unvaccinated. This is because suggestive, rather than directive, messages allow room for people to exercise their own free will. <a href="https://doi.org/10.3389/fcomm.2019.00056">Studies in health communication</a> also suggest several other strategies for reducing reactance, ranging from providing choices to evoking empathy.</p>
<h2>Bandwagon effects</h2>
<p>Perhaps more important – given people’s reliance on smartphones and social networking – is to make better use of the technological features of interactive media, which includes websites, social media, mobile apps and games. Clever use of digital media can help convey strong health messages without triggering reactance.</p>
<p><a href="https://doi.org/10.1016/j.chb.2020.106270">Research in our lab</a> shows that people’s responses to media messages can be influenced by the approval of anonymous others on the internet, in the same way that <a href="https://doi.org/10.1145/1358628.1358873">consumers rely</a> on other people’s opinions and star ratings for making purchasing decisions online. In a <a href="https://doi.org/10.1080/10410236.2021.1888450">recent study</a>, we discovered that freedom-threatening health messages can be made more palatable if they are accompanied by a large number of likes on social media from other people. When a lot of others were seen as supporting the advocacy message, the forceful language did not seem any more threatening to their freedom than the gentler version. </p>
<p>In other words, we found that the number of likes has a strong “bandwagon effect” in reducing reactance. We also discovered that providing an option to comment on the health message imbues a higher sense of personal agency and greater acceptance of the message.</p>
<p>In another <a href="https://doi.org/10.1080/10410236.2021.1885772">recent experiment</a>, we found that customization, or the ability to tailor one’s phone or online site to one’s liking, can also aid health communication. Whether it is a phone app, dating site or social media feed, customizing a digital space allows people to reflect their personality. Seeing a health advocacy message in such a personalized space does not pose as much of a threat in such venues because people feel secure in their identity. We found that customization helps reduce negative reactions to health messages by increasing one’s sense of identity.</p>
<p>A communication strategy that is sensitive to psychological reactance could empower the holdouts to willingly get vaccinated instead of grudgingly comply with a mandate.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/167601/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>S. Shyam Sundar receives funding from U. S. National Science Foundation. </span></em></p>Subtly shifting the crafting and delivery of public health messaging on COVID-19 vaccines could go a long way toward persuading many of the unvaccinated to get the shot.S. Shyam Sundar, James P. Jimirro Professor of Media Effects & Co-Director, Media Effects Research Laboratory, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1668112021-09-07T12:52:18Z2021-09-07T12:52:18ZMedicine is an imperfect science – but you can still trust its process<figure><img src="https://images.theconversation.com/files/418963/original/file-20210901-25-big4r.jpg?ixlib=rb-1.1.0&rect=0%2C72%2C2039%2C1085&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Intensive care physicians are yet again facing ICU bed and staff shortages as severe COVID-19 cases rise.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/hospital-coronavirus-emergency-department-ward-royalty-free-image/1321692378?adppopup=true">gorodenkoff/iStock via Getty Images Plus</a></span></figcaption></figure><p><em>The Conversation is running a series of dispatches from clinicians and researchers operating on the front lines of the coronavirus pandemic. You can <a href="https://theconversation.com/us/topics/covid-19-front-lines-84846">find all of the stories here</a>.</em> </p>
<p>As an intensive care physician in Southern California who endured the onslaught of COVID-19 in 2020, it has been deeply disheartening to experience chillingly familiar scenes all over again. The ICUs in the University of California San Diego Health hospital network where <a href="https://profiles.ucsd.edu/venktesh.ramnath">I work</a> are again overflowing – especially with patients who need ventilators. Families peer through tinted hospital windows for glimpses of loved ones. And <a href="https://www.washingtonpost.com/health/staff-shortages-hospitals-covid/2021/08/12/85f636b4-fa97-11eb-8a67-f14cd1d28e47_story.html">hospital administrators scramble</a> to keep up with necessary staffing and beds to accommodate the influx of patients.</p>
<p>What is so vexing is that COVID-19 is still the culprit, despite the availability of <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7034e2.htm">highly effective vaccines</a> that <a href="https://doi.org/10.1038/d41586-021-02054-z">slashed U.S. COVID-19 daily case numbers and hospitalizations</a> within months. The vaccines also allowed economies to <a href="https://budgetmodel.wharton.upenn.edu/issues/2021/3/1/epidemiological-and-economic-effects-of-covid-19-vaccine">begin to recover</a> and provided a way for people to experience some sense of normalcy again. </p>
<p>In early spring, the efficacy of the vaccine engendered hope that herd immunity – in which infectious viral spread is prevented through a high proportion of the population’s being immune to the disease – <a href="https://www.wsj.com/articles/well-have-herd-immunity-by-april-11613669731">could be within reach</a> in months. Instead, pandemic panic is again suffocating us, largely because a large part of the public <a href="https://www.nytimes.com/2021/07/31/us/virus-unvaccinated-americans.html">still shuns vaccination</a> – with only 62% of the eligible U.S. population <a href="https://covid.cdc.gov/covid-data-tracker/#vaccinations_vacc-total-admin-rate-total">fully vaccinated</a> as of early September 2021.</p>
<p>I wanted an answer to the obvious question: Why?</p>
<h2>Straight from the source</h2>
<p>So I turned to my patients for answers. At the bedside in their hospital rooms, I first asked about how they were feeling and performed detailed exams before addressing the elephant in the room. “Did you receive the COVID-19 vaccine?” And if not, I gently asked, “Did you have a specific reason you could share with me, so I can understand better?”</p>
<p>Somewhat surprisingly, patients candidly told me their reasons for avoiding the vaccine.</p>
<p>A common response I heard was that it was simply inconvenient. “I was too lazy and I didn’t get around to it,” some admitted, looking away sheepishly as they did so. Curiously, they did not consider the myriad “inconveniences” of becoming infected, such as medical complications – including death – and associated costs for treatment, lost work, dependence on others for basic necessities such as child care, the risk of infecting family members, the potential for developing <a href="https://theconversation.com/deciphering-the-symptoms-of-long-covid-19-is-slow-and-painstaking-for-both-sufferers-and-their-physicians-164754">long-haul COVID-19</a> and more.</p>
<p>Others expressed a fervid distrust of vaccine-testing methods, stating that people had been “guinea pigs in past vaccine experiments that later caused autism.” Yet more than 25 studies in the past 20-odd years have disproved any <a href="https://www.healthychildren.org/English/safety-prevention/immunizations/Pages/Vaccine-Studies-Examine-the-Evidence.aspx">causal link between vaccines and autism</a>. </p>
<p>Some felt that the forceful public messaging to get vaccinated belied true motivations of the authorities, adding: “I mean, why are they pushing this so hard? Something must be wrong with it.” Yet few question the strong public health stance on healthy eating practices and exercise, or wearing seat belts while driving. </p>
<p>Still others feared the possibility of life-threatening side effects: “Thousands had heart attacks from the vaccine – it’s all on the CDC website,” they told me. So I took <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/myocarditis.html?s_cid=11374:covid%20vaccine%20heart%20problems:sem.ga:p:RG:GM:gen:PTN:FY21">a close look</a> at the CDC website to understand their claims better. </p>
<p>Reports of heart inflammation occurred in 699 cases out of 177 million vaccinated people, or 0.0004%, with causal links to the vaccines still being investigated. Development of blood clots causally associated with the Johnson & Johnson vaccine are <a href="https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-05-12/07-COVID-Shimabukuro-508.pdf">also extremely rare</a>, occurring in 28 cases out of 8.73 million doses given as of May 7, 2021 – a rate of 0.0003%. This extremely low risk of blood clots is still significantly lower than the <a href="https://doi.org/10.1136/bmj.n1931">risk of blood clots</a> from an <a href="https://www.nytimes.com/2021/08/27/health/blood-clots-coronavirus.html">actual COVID-19</a> infection.</p>
<h2>Medicine as art and imperfect science</h2>
<p>In some cases, political affiliation can <a href="https://www.economist.com/united-states/2021/07/27/americas-vaccination-woes-cannot-be-blamed-only-on-politics">partially explain</a> vaccine antipathy. But my patients’ responses highlighted two other themes to me.</p>
<p>First, people often forget that medicine is an art <a href="http://dx.doi.org/10.1136/mh.26.1.18">based on applied science</a>, not a deductive science based on irrefutable forces in nature like gravity. Patients and families often ask me in the ICU to predict what will happen to loved ones unequivocally, only to be disappointed when I avoid speaking in certainties.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An ICU doctor hugs and comforts a patient in a COVID-19 ICU" src="https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418964/original/file-20210901-15-19x8jad.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Having to deliver devastating news and uncertainties about patient outcomes has taken a heavy toll on ICU physicians during the COVID-19 pandemic.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/dr-joseph-varon-hugs-and-comforts-a-patient-in-the-covid-19-news-photo/1229807339?adppopup=true">Go Nakamura/Getty Images News</a></span>
</figcaption>
</figure>
<p>Once viewed as <a href="https://doi.org/10.1136/bmj.317.7174.1729">omniscient authorities</a>, doctors now openly acknowledge that limitations of medical data require scrutiny and careful application to particular circumstances. COVID-19 has reinforced our appreciation that there are no perfect cures or 100% guarantees of success. Rather, medicine is governed by what is probable. What are the chances I still may have cancer if the test result returns negative? Am I more or less likely to survive pneumonia by taking this specific antibiotic?</p>
<p>Doctors must then engage in <a href="https://doi.org/10.1016/j.chest.2020.05.548">thoughtful analysis</a> of the strengths and weaknesses of scientific methods and data to optimize and tailor our recommendations for individual patients – without the luxury of perfect or even complete datasets to rely on. The vaccine has clearly been shown – its rare side effects notwithstanding – to provide an overwhelmingly high likelihood of benefit over potential risks to almost all individuals. This <a href="https://doi.org/10.1001/jama.2021.11717">includes people</a> who have been <a href="https://apnews.com/article/science-health-coronavirus-pandemic-ad52011f4ca1853fad6eee41a7310c2e">previously infected with COVID-19</a>. Yet the unvaccinated continue to fixate on rare side effects to justify skipping the shot.</p>
<h2>Vaccines are medicines too</h2>
<p>Many of my patients also seem to view vaccines and other public health-based recommendations like offers to buy a used car – with skepticism and independence, threatening to walk away at any moment. Doing one’s part to stop the spread of disease is a culturally nuanced civic virtue, like <a href="https://doi.org/10.1016/j.trf.2014.01.004">safe driving</a>, which transcends absolute autonomy. In the U.S., most drivers willingly do not drive while intoxicated, cross lanes without warning or block other cars that are trying to merge. These are norms that make driving in the U.S. relatively efficient, safe and even pleasant compared with some other countries. </p>
<p>The path to herd immunity, like highway safety, requires majority participation without immediate guarantees of complete personal freedom. Vaccines succeed not because they are 100% risk-free to the individual but because collective efforts focus on achieving the common good.</p>
<p>Oddly, at the same time that my patients rejected the vaccine, they showed strong interest in receiving other types of medicine “shots” like monoclonal antibodies – which mimic natural antibodies – or anti-inflammatory medications. While <a href="https://www.covid19treatmentguidelines.nih.gov/management/clinical-management/">some of these treatments</a> have demonstrated benefits in certain situations – <a href="https://doi.org/10.1001/jama.2021.2747">others</a> <a href="https://doi.org/10.1056/NEJMoa2028700">have not</a>. And some present the risk of <a href="https://www.fox19.com/2021/08/21/seriously-yall-stop-it-fda-dispels-myth-about-ivermectin-covid-cure/">very serious harm</a>. </p>
<p>I reminded my patients that the COVID-19 vaccine stimulates a person’s own immune system to make <a href="https://theconversation.com/what-happens-when-the-covid-19-vaccines-enter-the-body-a-road-map-for-kids-and-grown-ups-164624">antibodies that can neutralize the virus</a> and that surpass the capabilities of <a href="https://www.webmd.com/vaccines/covid-19-vaccine/news/20210826/monoclonal-antibodies-vs-vaccines-vs-covid-19">commercially created antibody formulations</a>. So the vaccines help prevent infection and development of serious illness from COVID-19 in the first place. People who experience the <a href="https://theconversation.com/what-is-a-breakthrough-infection-6-questions-answered-about-catching-covid-19-after-vaccination-164909">rare breakthrough infections</a> following vaccination generally have a <a href="https://www.wsj.com/articles/breakthrough-cases-covid-19-delta-variant-11627596643">shorter and milder course of COVID-19 infection</a> and are far less likely to <a href="https://doi.org/10.1093/cid/ciab543">end up hospitalized</a> than those who are unvaccinated. Vaccines <a href="https://doi.org/10.1038/s41586-021-03738-2">also confer</a> <a href="https://www.npr.org/sections/goatsandsoda/2021/08/30/1032520934/immunity-to-covid-19-could-last-longer-than-youd-think?ft=nprml&f=1032520934">longer-term protection</a>, whereas the other medications are used reactively – when a serious infection has already begun – and those medications have <a href="https://www.coronaviruspreventionnetwork.org/coronavirus-vaccine-and-antibody-science">shorter-term results</a>.</p>
<h2>How past vaccination efforts succeeded</h2>
<p>In the past, many vaccines that successfully vanquished societal outbreaks of <a href="https://www.cdc.gov/polio/what-is-polio/polio-us.html">polio</a>, <a href="https://www.historyofvaccines.org/timeline/measles">measles</a> and <a href="https://www.historyofvaccines.org/content/articles/mumps">mumps</a> are now routinely administered in childhood with minimal objection, despite the fact that there is no such thing as <a href="https://www.cdc.gov/vaccines/vac-gen/side-effects.htm">zero risk</a>.</p>
<p>As I continue to have conversations with patients who suffer greatly from COVID-19 illness as a direct consequence of having avoided the vaccine, my own pain – for being an ineffective healer and witness to such loss – is inexorable. Overcoming this fourth wave of COVID-19 still feels out of reach until our vaccination efforts can somehow better emphasize the effectiveness of vaccines, even when scientifically imperfect, and prioritize civic health care responsibilities over pure autonomy. If not, I fear that our battle against COVID-19 will rage on.</p>
<p>[<em>Get the best of The Conversation, every weekend.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybest">Sign up for our weekly newsletter</a>.]</p><img src="https://counter.theconversation.com/content/166811/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Venktesh Ramnath does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A critical care doctor brings a frontlines perspective to the frustration of dealing firsthand with vaccine hesitancy and discusses the limitations of science and medicine.Venktesh Ramnath, Associate Clinical Professor of Medicine, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1667542021-08-26T18:13:32Z2021-08-26T18:13:32ZVital Signs: with vaccine thresholds come the danger of repeating past mistakes<p>In 2020 when people talked about “living with COVID” it was code for letting the virus rip. It was really a plan for many to “die with COVID”.</p>
<p>Thankfully our political leaders listened to experts. </p>
<p>In general, Australia managed the pandemic’s public health and economic challenges better than most countries. The glaring exceptions were, of course, our vaccination strategy and our quarantine arrangements. </p>
<p>With vaccines we didn’t buy a properly diversified portfolio of vaccines, didn’t act with a sense of urgency — “<a href="https://theconversation.com/view-from-the-hill-new-expert-advice-is-in-dont-say-its-not-a-race-161935">It’s not a race</a>,” said the Prime Minister and other ministers — and didn’t have an effective plan for getting jabs into arms quickly. </p>
<p>With quarantine arrangements we failed to build fit-for-purpose facilities akin to the one in Howard Springs outside Darwin. Instead we relied on poorly ventilated hotels in the heart of our biggest and most densely populated cities.</p>
<p>Now, with the roll-out of high-efficacy vaccines against COVID-19, we are beginning to have a national discussion genuinely about how to live with COVID.</p>
<p>It is vital that during that discussion we don’t repeat the mistakes of 2020. </p>
<p>Those mistakes all sprang from false economies. </p>
<p>The federal government thought we could save a few bucks by gambling on vaccine purchases. It favoured vaccines that could be made locally more as a back-door industry policy rather than strategic supply-chain management. It thought using hotels as quarantine facilities could help financially support the hospitality sector.</p>
<p>Pinching pennies cost us. Big time.</p>
<p>It is imperative we don’t fall into the trap of false economies again by opening up too soon, before what is needed to stay open is in place.</p>
<h2>Vaccination milestones</h2>
<p>The <a href="https://www.pm.gov.au/sites/default/files/media/national-plan-to-transition-australias-national-covid-19-response-july2021.pdf">national plan</a> about when Australia will “reopen” is pegged to vaccination milestones.</p>
<p>We’re still in the first of the four-phase plan. We will move to Phase B (the “vaccine transition phase”) when 70% of eligible Australians over the age of 16 are vaccinated. At 80% we move to Phase C (the “vaccination consolidation phase”).</p>
<p>At this 80% threshold the plan is for only “highly targeted lockdowns”, the end of passenger caps for vaccinated Australians returning home, and restarting outbound travel for vaccinated Australians.</p>
<p>There are important epidemiological debates about whether 70% and 80% are the right thresholds. I’m just an economist, so I’m not going to get into that here.</p>
<p>But if we accept, for the sake of argument, that 80% is the practically relevant threshold for moving to Phase C of the national plan, then we should at least insist on getting the arithmetic right.</p>
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<p>On this, there are two key questions.</p>
<h2>80% of what?</h2>
<p>The first is about the vaccination rate. Moving to Phase C calls for 80% of the “eligible” population to be fully vaccinated. </p>
<p>But that’s not 80% of <a href="https://www.abs.gov.au/AUSSTATS/abs%40.nsf/Web%2BPages/Population%2BClock?opendocument=&ref=HPKI">Australia’s population</a> of 25.8 million. </p>
<p>Rather, it’s 80% of the population <a href="https://www.doherty.edu.au/uploads/content_doc/DohertyModelling_NationalPlan_and_Addendum_20210810.pdf">aged 16 and over</a> — about 16.6 million people, or 64% of the population. </p>
<p>If the national plan is changed to make it 80% of the population aged 12 and over, that would be about 17.6 million people, or 68% of the population.
To paraphrase the United States politician <a href="https://www.senate.gov/artandhistory/history/minute/Senator_Everett_Mckinley_Dirksen_Dies.htm">Everett Dirksen</a>, a million here, a million there, and pretty soon you’re talking about real numbers.</p>
<p>There are two points here. </p>
<p>First, the much-touted 80% threshold is really only 64% of the whole population. Yet herd-immunity levels — where outbreaks die out — are typically expressed as a proportion of the entire population. Given the basic reproduction rate of the Delta variant and current vaccine effectiveness, the actual <a href="https://www.medrxiv.org/content/10.1101/2020.12.15.20248278v2.full">herd immunity vaccination threshold</a> could easily be north of 85%.</p>
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Read more:
<a href="https://theconversation.com/how-will-delta-evolve-heres-what-the-theory-tells-us-165243">How will Delta evolve? Here's what the theory tells us</a>
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<p>Second, the longer that lockdowns continue, the stronger the temptation for politicians to shift to targets that are easier to achieve. Though this might be politically convenient, it would be disastrous.</p>
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Read more:
<a href="https://theconversation.com/should-we-give-up-on-covid-zero-until-most-of-us-are-vaccinated-we-cant-live-with-the-virus-166269">Should we give up on COVID-zero? Until most of us are vaccinated, we can't live with the virus</a>
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<h2>80% plus how long?</h2>
<p>The second question is how long after hitting the 80% threshold do we begin moving from Phase C to Phase D.</p>
<p><a href="https://www.nejm.org/doi/10.1056/NEJMoa2034577?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed">Clinical trial data</a> for the Pfizer vaccine suggests the best immune response occurs about two weeks after the second dose. The federal <a href="https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines/is-it-true/is-it-true-how-long-does-it-take-to-have-immunity-after-vaccination">Department of Health emphasises</a> that:</p>
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<p>Individuals may not be fully protected until 7-14 days after their second dose of the Pfizer (Comirnaty) or AstraZeneca (Vaxzevria) vaccine. </p>
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Read more:
<a href="https://theconversation.com/how-long-do-covid-vaccines-take-to-start-working-161876">How long do COVID vaccines take to start working?</a>
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<p>So if the government is going to stick to the spirit of the national plan, we really should be waiting until two weeks after 80% of the 12+ population has been vaccinated.</p>
<p>Again, there will be a big political temptation to reopen the day of the “threshold” second jab, rather than when it really becomes effective.</p>
<h2>Don’t fall at the final hurdle</h2>
<p>Australians have put up with a lot since early 2020. A devastating virus, lockdowns, uncertainty, isolation from loved ones, economic pain, and differing degrees of government competence.</p>
<p>It is essential we finish this race properly. We must not let our political leaders reopen too early by redefining the targets they have signed up for. It would be the ultimate false economy.</p><img src="https://counter.theconversation.com/content/166754/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Holden is President-elect of the Academy of Social Sciences in Australia.</span></em></p>Australia could again fall into the trap of false economies by opening up too soon.Richard Holden, Professor of Economics, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1657002021-08-11T14:58:31Z2021-08-11T14:58:31ZWhy population immunity is not a realistic goal in Africa’s bid to control COVID-19<figure><img src="https://images.theconversation.com/files/415427/original/file-20210810-15-oqn9q2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">COVID-19 vaccination in Africa is speeding up. </span> <span class="attribution"><span class="source">Habimana Thierry/Anadolu Agency via Getty Images</span></span></figcaption></figure><p>In public health, an important goal of vaccination and immunisation is to reach population or herd immunity. This is why the term comes up often in relation to the COVID-19 pandemic. And it helps to be clear about what it means.</p>
<p>Think of a community where some people have been immunised against an infectious disease and others have not. “Herd immunity” or “population immunity” is the protection that at-risk people get indirectly from immunised people. The indirect protection is attained when a certain proportion (threshold) of community members has acquired immunity to the infectious disease. </p>
<p>The threshold for reaching population immunity depends on many factors. One is the effectiveness of the vaccine. Another is how many people get the vaccine. A third is how long the immunity given by the vaccine lasts. </p>
<p>Then there’s the infectiousness of the disease. For example, the population immunity threshold for a highly infectious disease, like measles, is estimated at <a href="https://pubmed.ncbi.nlm.nih.gov/31551070/">95%</a>. Only when 95% of a population is immune from measles will the remaining 5% of the population be protected. </p>
<p>The estimates are highly variable for COVID-19. They range from <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151357/">50% to 85%</a>, assuming the effectiveness of the available vaccines is not greatly changed by new SARS-CoV-2 variants. </p>
<p>Vaccine-induced immunity following complete vaccination against measles is long-lived. We don’t know yet how long COVID-19 vaccine-induced immunity lasts. But data is rapidly accumulating.</p>
<p>People acquire immunity either from being infected and recovering, or from being vaccinated, or a combination of the two. There are risks to relying on natural acquired immunity in the case with COVID-19. The outcome of an infection is unpredictable and sometimes fatal. Therefore, the safest and fastest way to attain population immunity is through <a href="https://jamanetwork.com/journals/jama/fullarticle/2772168">vaccination</a>. </p>
<p>Smallpox was eradicated in <a href="https://www.who.int/health-topics/smallpox#tab=tab_1">1980</a> through vaccination-induced population immunity. We no longer need to administer vaccines against smallpox. Ideally, vaccination-induced population immunity can control the COVID-19 pandemic. </p>
<p>But evidence is <a href="https://theconversation.com/covid-study-finds-lower-antibody-activity-against-delta-variant-at-single-dose-but-vaccines-still-work-164351">emerging</a> that the effectiveness of currently available COVID-19 vaccines may be declining, because of continually mutating SARS-COV-2. This has led some <a href="https://theconversation.com/covid-19-herd-immunity-its-not-going-to-happen-so-what-next-165471">experts to caution</a> that we can “forget about herd immunity” and instead, “vaccinate enough people quickly enough”. </p>
<p>It is still worth acknowledging that vaccine rollout is speeding up. But presently, COVID-19 vaccine-induced population immunity appears to be a moving target and unrealistic.</p>
<h2>Population immunity through vaccination</h2>
<p>Sweden’s attempted to attain population immunity through natural infection proved to be highly risky and unattainable. It resulted in a sharp increase in <a href="https://jamanetwork.com/journals/jama/fullarticle/2772167">COVID-19 cases and loss of lives</a>. The country then turned to public health interventions and is now rolling out COVID-19 vaccines. </p>
<p>In contrast, Israel quickly rolled out its vaccination programme in <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01018-7/fulltext">December 2020</a> with the Pfizer/BioNTech COVID-19 vaccine. The efficacy of the vaccine is as high as 95% against the original SARS-COV-2. This efficacy is reported to be reduced to around <a href="https://pubmed.ncbi.nlm.nih.gov/34289274/">88%</a> against emerging variants. </p>
<p>At the time of writing, Israel had fully vaccinated <a href="https://ourworldindata.org/covid-vaccinations?country=OWID_WRL">5.39 million individuals, representing 59.6% of the total population</a>. The public health benefits were almost immediate. These included a significantly lower COVID-19 disease burden and a return to the pre-pandemic way of life. </p>
<p>This was unfortunately interrupted by the delta variant. The delta variant is <a href="https://asm.org/Articles/2021/July/How-Dangerous-is-the-Delta-Variant-B-1-617-2">60% more transmissible than the alpha variant</a>. If vaccine coverage in Israel was higher and included younger population groups, the country would likely not be experiencing a resurgence in SARS-CoV-2 infections. </p>
<p>Israel provides valuable lessons on the benefits of vaccinating as many people as quickly as possible – even without attaining population immunity. Evidently, COVID-19 vaccines must be rapidly deployed and have high uptake to save lives and livelihoods. </p>
<h2>Vaccine-induced population immunity in Africa</h2>
<p>Key barriers to achieving population immunity through current vaccination approaches include the inequitable supply of and access to COVID-19 vaccines, and emerging SARS-CoV-2 variants. </p>
<p>African countries are among those facing disproportionate vaccine supply delays and shortages. The Africa Centres for Disease Control and Prevention <a href="https://africacdc.org/covid-19-vaccination/">estimated</a> that by the beginning of August 2021, 3.42% of the continent’s population had received at least one dose of a COVID-19 vaccine. Only 1.46% were fully vaccinated. This is in stark contrast to the <a href="https://www.bloomberg.com/graphics/covid-vaccine-tracker-global-distribution/">European region</a>, where 60.9% of the population is estimated to have received at least a single dose. Around 52.5% were fully vaccinated as at 8 August 2021. </p>
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Read more:
<a href="https://theconversation.com/interested-in-vaccine-rollouts-across-africa-heres-a-map-to-guide-you-156802">Interested in vaccine rollouts across Africa? Here's a map to guide you</a>
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<p>The unequal coverage is largely the result of most wealthy countries securing large supplies of vaccines early on – often more than they needed. Some high-income countries are considering giving their populations a third dose of COVID-19 vaccines. This will worsen the access problems for countries in Africa. <a href="https://www.unicef.org/press-releases/we-need-speed-and-simplicity-remove-barriers-acquisition-manufacture-and">Global agencies have called</a> for these high-income countries to share their surplus vaccines rather than “topping up” vaccine-induced immunity with a third dose.</p>
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Read more:
<a href="https://theconversation.com/covid-who-calls-for-moratorium-on-booster-shots-is-it-justifiable-165762">COVID: WHO calls for moratorium on booster shots – is it justifiable?</a>
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<p>Aside from vaccine supply bottlenecks, other <a href="https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(21)00097-8/fulltext">logistical and operational barriers</a> exist in the African context. </p>
<p>In some cases, low vaccination rates have been recorded among populations with negative perceptions of the vaccines, brought on by widespread vaccine misinformation and disinformation, as well as limited knowledge about the safety of these vaccines. It’s difficult to quantify the role of misinformation in vaccine uptake given that vaccine demand currently outstrips supply in most African countries. </p>
<p>Still, there is a need for intensive, context-specific, and culturally appropriate community engagement campaigns to improve knowledge about COVID-19 vaccines and address public concerns about these lifesaving interventions. </p>
<p>With the delays in vaccination in Africa, concerns are growing that some variants of the virus could continue to fuel outbreaks of the disease or make the available vaccines less effective.</p>
<p>Under these conditions, attaining population immunity on the continent is unrealistic. The continental goal to <a href="https://news.un.org/en/story/2021/02/1083882">vaccinate at least 20% of the African population by the end of 2021</a> currently appears far off. But still, the only way ahead is improved vaccine access, rapid rollout of the available vaccines and community engagement to encourage uptake. </p>
<h2>Looking ahead</h2>
<p>In general, vaccine-induced population immunity is critical to interrupting the transmission of deadly pathogens and controlling outbreaks and pandemics.</p>
<p>Some community members (young infants) are currently not eligible for COVID-19 vaccination. They will therefore have to depend on the decisions that adults make when offered COVID-19 vaccines.</p>
<p>Authorised COVID-19 vaccines are safe, effective, and integral to global public health efforts aimed at attaining population immunity. </p>
<p>Without equitable access, rapid and high uptake of COVID-19 vaccines worldwide, vaccine-induced population immunity against COVID-19 is merely an illusion. Therefore, vaccination rollout in Africa should be complemented with non-therapeutic interventions: social distancing, wearing face masks, regularly washing and sanitising hands.</p><img src="https://counter.theconversation.com/content/165700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In Africa, it’s more rational to prioritise vaccine access, rapid rollout and community engagement, than pushing the narrative of vaccine-induced population immunity.Edina Amponsah-Dacosta, Postdoctoral Research Fellow, Vaccines for Africa Initiative, University of Cape TownBenjamin Kagina, Senior Research Officer, Vaccines For Africa Initiative, Faculty of Health Sciences, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1649422021-08-05T02:58:23Z2021-08-05T02:58:23ZWe may need to vaccinate children as young as 5 to reach herd immunity with Delta, our modelling shows<figure><img src="https://images.theconversation.com/files/414473/original/file-20210804-12-feze9m.jpg?ixlib=rb-1.1.0&rect=0%2C1%2C1000%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/group-elementary-pupils-classroom-138148427">from www.shutterstock.com</a></span></figcaption></figure><p>Recently released <a href="https://www.doherty.edu.au/news-events/news/doherty-institute-modelling-report-for-national-cabinet">modelling</a> from the Doherty Institute, which the federal government used to back its roadmap out of the pandemic, misses one critical point — the importance of vaccinating children.</p>
<p>The Doherty modelling instead focuses on vaccinating 70-80% of the adult population as thresholds for easing various restrictions, such as lockdowns. It says vaccinating younger adults, in particular, is important to reach these thresholds.</p>
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<p>However, <a href="https://www.medrxiv.org/content/10.1101/2021.07.16.21260642v1">our modelling</a> shows vaccinating children is vital if we are to reach herd immunity, which would allow us to ease restrictions and safely open up. </p>
<p>This would mean potentially vaccinating children as young as 5 years old. </p>
<p>However, we are still waiting to see if this is safe and effective, with trials under way in the United States. So we need a plan that assumes we may never achieve herd immunity.</p>
<p>Here’s what our modelling shows and how it differs from the modelling used to advise the federal government.</p>
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Read more:
<a href="https://theconversation.com/we-need-to-start-vaccinating-people-in-their-20s-and-30s-according-to-the-doherty-modelling-an-epidemiologist-explains-why-165540">We need to start vaccinating people in their 20s and 30s, according to the Doherty modelling. An epidemiologist explains why</a>
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<h2>Here’s what we did</h2>
<p><a href="https://www.medrxiv.org/content/10.1101/2021.07.16.21260642v1">Our modelling</a>, which we’ve uploaded as a pre-print and has yet to be peer-reviewed, considers different vaccine strategies for Australia to achieve herd immunity. That’s when we can expect no sustained transmission of the virus in the community.</p>
<p>We take into account the Delta variant, which is twice as infectious as the original Wuhan strain of the virus, and has a reproduction number estimated between <a href="https://fm.cnbc.com/applications/cnbc.com/resources/editorialfiles/2021/07/30/CDC_slides.pdf">5 and 10</a>. In other words, this is when one person infected with Delta is estimated to infect 5-10 others.</p>
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Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
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<p>We also consider different contact patterns across various age groups. This is because some age groups are more mobile and have many contacts. If infected, these people are more likely to infect many others, particularly of similar age, which can lead to reservoirs of transmission. </p>
<p>We combine this information with possible vaccine effects. These include the possibility of having the vaccine then becoming infected, having symptoms, and if infected, how serious the illness is and how infectious people are. </p>
<p>This allows us to model what’s likely, given we’re focused on the Delta variant for now, and allows us to assess the impact of strategies across different age groups, types of vaccines and percentage vaccinated.</p>
<p><a href="https://covid-19-aithm.shinyapps.io/vaccine_coverage_analysis/">Our interactive tool</a> also allows rapid response to changing information, such as new variants, or new evidence about vaccine impact.</p>
<h2>Delta is more infectious</h2>
<p>The Wuhan strain had a <a href="https://ourworldindata.org/explorers/coronavirus-data-explorer?zoomToSelection=true&time=2020-03-01..latest&pickerSort=asc&pickerMetric=location&Metric=Reproduction+rate&Interval=7-day+rolling+average&Relative+to+Population=true&Align+outbreaks=false&country=USA%7EGBR%7ECAN%7EDEU%7EITA%7EIND">basic reproduction number of 2.5</a>. This means, at the start of the pandemic, one person infected with it was expected to infect 2.5 others.</p>
<p>If the Delta variant is twice as infectious, this means its basic reproduction number may be over 5 (at the lower range of international estimates). So this changes the number (and type) of people we need to vaccinate to reach herd immunity considerably.</p>
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<p>The simplest form of the herd immunity equation would suggest we needed to fully immunise 60% of the population to achieve herd immunity for the Wuhan strain but as much as 80% for the Delta variant.</p>
<p>If we take into account how different age groups mingle or are in contact with others, the situation is worse. </p>
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Read more:
<a href="https://theconversation.com/is-it-more-infectious-is-it-spreading-in-schools-this-is-what-we-know-about-the-delta-variant-and-kids-163724">Is it more infectious? Is it spreading in schools? This is what we know about the Delta variant and kids</a>
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<p>For the Wuhan strain, children were not as infectious or susceptible to infection and we predict that if we vaccinate 65% of the adults, transmission would not continue among children.</p>
<p>However, with the Delta variant, we predict children will continue to infect other children, even when most adults are vaccinated.</p>
<p>We also know both the AstraZeneca and Pfizer vaccines are <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2108891">less able to protect</a> against the Delta variant, with a reduced efficacy after one dose and slightly reduced efficacy after two doses.</p>
<p>All this makes achieving herd immunity a great challenge. </p>
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Read more:
<a href="https://theconversation.com/when-will-we-reach-herd-immunity-here-are-3-reasons-thats-a-hard-question-to-answer-164560">When will we reach herd immunity? Here are 3 reasons that's a hard question to answer</a>
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<p>We estimate if the reproduction number is 5, then vaccinating 85% of the population, including children down to age 5, will be necessary to achieve herd immunity. </p>
<p>If the reproduction number is as low as 3, then vaccinating children will not be necessary to achieve herd immunity and we will only need to vaccinate 60% of the population.</p>
<p>The Doherty modelling uses an effective reproduction number of 3.6. This explains why its modelling does not see vaccinating children as critical to reaching herd immunity. This is the major difference between our model and theirs.</p>
<h2>What happens next?</h2>
<p>Of course, new variants may arise pushing Delta aside, and the world post-COVID is unpredictable. </p>
<p>The lesson from Delta is if we don’t vaccinate children, we may need to continue some form of public health action to prevent large-scale circulation of the virus. </p>
<p>This would not require stringent lockdown, but may require ongoing mask use and physical distancing, including in children. The alternative is to reduce the focus on case numbers, expect transmission and focus on protecting the most vulnerable.</p>
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<strong>
Read more:
<a href="https://theconversation.com/should-we-vaccinate-children-against-covid-19-we-asked-5-experts-165316">Should we vaccinate children against COVID-19? We asked 5 experts</a>
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<h2>Do we need to reach herd immunity?</h2>
<p>Herd immunity is not the only possible target. Even if we don’t reach full herd immunity, we may achieve “herd protection”. This provides some reduced risk to people who can’t or won’t be vaccinated, and it will make outbreaks smaller and easier to control.</p>
<p>And without full herd immunity, individuals still benefit from vaccination as they are dramatically less likely to die from COVID.</p>
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Read more:
<a href="https://theconversation.com/how-well-do-covid-vaccines-work-in-the-real-world-162926">How well do COVID vaccines work in the real world?</a>
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<h2>Do we need to change our vaccination strategy?</h2>
<p>We predict Australia’s strategy of vaccinating the elderly and vulnerable first is the best strategy for reducing deaths under most circumstances, particularly when there is insufficient vaccine available. </p>
<p>But once the most vulnerable groups have been covered, we should turn our attention to the highest transmitters to achieve herd protection. In Australia, this group is the late teens and young adults. </p>
<p>Whether we next focus on vaccinating children is controversial and many people have voiced their concerns about going down this path. This is because COVID is generally a very mild illness for most children — although <a href="https://www.thelancet.com/journals/lanchi/article/PIIS2352-4642(21)00124-3/fulltext">long COVID</a> and <a href="https://jamanetwork.com/journals/jama/article-abstract/2777026">life-threatening complications</a> can arise.</p>
<p>So we need to balance the risks with benefits. But included in the benefits should be the potential benefit of herd protection and the freedoms that may bring.</p>
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Read more:
<a href="https://theconversation.com/national-cabinets-plan-out-of-covid-aims-too-low-on-vaccinations-and-leaves-crucial-questions-unanswered-165447">National Cabinet's plan out of COVID aims too low on vaccinations and leaves crucial questions unanswered</a>
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<img src="https://counter.theconversation.com/content/164942/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma McBryde receives funding from NHMRC. She is affiliated with the Australian Tuberculosis Forum and the Austrasian Society of Infectious Diseases. </span></em></p>But herd immunity is not our only option. If we don’t vaccinate children, we may have to settle for lesser protection of the population.Emma McBryde, Professor of Infectious Disease and Epidemiology, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1654802021-08-02T15:14:15Z2021-08-02T15:14:15ZPasha 118: Herd immunity isn’t achievable. We need to learn to live with COVID-19<figure><img src="https://images.theconversation.com/files/414130/original/file-20210802-17-r0n2b2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>In the first year of the COVID-19 pandemic the phrase “herd immunity” was bandied about a lot by heads of state as well as health officials. This ideal end state was described as the moment when the virus had been beaten, and everyone could return to a normal life. </p>
<p>But a great deal has changed in the intervening months. Firstly, the virus has mutated in ways that make it spread more quickly, and in ways that make it potentially more resistant. </p>
<p>In addition, the unequal distribution of vaccines, combined with slow rollouts in a great many countries as well as vaccine hesitancy, has thrown initial planning off course. </p>
<p>So what’s the alternative?</p>
<p>We must learn to live with the virus. To do this, reaching high levels of vaccination is crucial. This will minimise the number of people being hospitalised and dying from COVID-19. It does not mean that COVID-19 will be gone but it means clusters of outbreaks will be smaller and less damaging to countries. Health facilities will be able to cope better. </p>
<p>In today’s episode of Pasha, Shabir A. Madhi, Dean of the Faculty of Health Sciences and Professor of Vaccinology at the University of the Witwatersrand, discusses the problems with herd immunity and how to deal with COVID-19 in the long term.</p>
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<p><strong>Photo:</strong><br>
“Herd Immunity concept” By Guillem Sartorio/AFP
By Ahmad Fozi found on <a href="https://www.shutterstock.com/image-illustration/herd-immunity-conceptset-man-symbol-word-1717344484">Shutterstock</a></p>
<p><strong>Music:</strong>
“Happy African Village” by John Bartmann, found on <a href="http://freemusicarchive.org/music/John_Bartmann/Public_Domain_Soundtrack_Music_Album_One/happy-african-village">FreeMusicArchive.org</a> licensed under <a href="https://creativecommons.org/publicdomain/zero/1.0/">CC0 1</a>.</p>
<p>“Expressions of the mind (Piano loop)” by ShadyDave, found on <a href="https://freesound.org/people/ShadyDave/sounds/325647/">Free Sound</a> licensed under under a <a href="http://creativecommons.org/licenses/by-nc/3.0/">Attribution Noncommercial License.</a></p><img src="https://counter.theconversation.com/content/165480/count.gif" alt="The Conversation" width="1" height="1" />
Governments should drop the idea of herd immunity. It risks leaving people feeling disillusioned by vaccination campaigns.Ozayr Patel, Digital EditorLicensed as Creative Commons – attribution, no derivatives.