tag:theconversation.com,2011:/ca-fr/topics/asymptomatic-84950/articlesAsymptomatic – La Conversation2023-07-19T15:02:22Ztag:theconversation.com,2011:article/2097742023-07-19T15:02:22Z2023-07-19T15:02:22ZAsymptomatic COVID-19 is linked to a gene variant that boosts immune memory after exposure to prior seasonal cold viruses<figure><img src="https://images.theconversation.com/files/538083/original/file-20230718-33186-1uz5zq.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2429%2C1220&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Genetics may play a role in COVID-19 disease severity.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/virus-wide-royalty-free-image/1312985523">BlackJack3D/E+ via Getty Images</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>A <a href="https://www.nature.com/articles/s41586-023-06331-x">common genetic variant</a> explains why some people are asymptomatic after being infected with the virus that causes COVID-19, according to our recently published study in the journal Nature.</p>
<p>Early in the pandemic, we were intrigued that many people did not develop COVID-19 symptoms while still testing positive for it. Because asymptomatic people are unlikely to seek medical help, we knew that collecting DNA samples to study the role of genetics in asymptomatic infections would be difficult. So instead, we took advantage of existing genetic data stored in the <a href="https://bethematch.org/about-us/how-we-help-patients/be-the-match-registry/">Be The Match</a> U.S. bone marrow donor registry. </p>
<p>We invited volunteers registered as donors to track their experience with COVID-19 via a smartphone app developed by the <a href="https://covid19.eurekaplatform.org">COVID-19 Citizen Science Study</a>. This allowed us to analyze the genetics of nearly 30,000 people without collecting biological samples and to identify COVID-19 positive individuals who never became sick.</p>
<p>We were particularly interested in analyzing the variation of <a href="https://www.uptodate.com/contents/human-leukocyte-antigens-hla-a-roadmap">human leukocyte antigen, or HLA, genes</a>. These key components of the immune system encode for proteins that display the viral particles that <a href="https://theconversation.com/coronavirus-b-cells-and-t-cells-explained-141888">T cells</a> – a group of immune system cells critical for fighting infections – recognize. Because HLA molecules are important in the immune response to pathogens and are highly variable among people, we thought they might play a role in COVID-19.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Computer illustration of HLA-B*1501." src="https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=815&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=815&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=815&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1024&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1024&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538087/original/file-20230718-18870-crqach.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1024&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">This is a 3D model of the protein that the gene variant HLA-B*15:01 codes for.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:HLA_B%5E1501.png">Pdeitiker/Wikimedia Commons</a></span>
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</figure>
<p>We found that 1,428 unvaccinated individuals reported a positive COVID-19 test, of whom 136 reported no COVID-19 symptoms. Our analysis identified a common variant of an HLA gene <a href="https://www.nature.com/articles/s41586-023-06331-x">called <em>HLA-B*15:01</em></a> that is associated with asymptomatic infection. This variant is present in <a href="https://doi.org/10.1016/j.humimm.2013.06.025">about 10% of the population with European ancestry</a>. </p>
<p>We found that people carrying the variant were more than twice as likely to remain asymptomatic after being infected with COVID-19, and those carrying two copies of this variant were more than eight times more likely to not have any symptoms. </p>
<p>Next, we used cells from people with the HLA variant who donated blood several years before the pandemic to see whether they had preexisting immunity to the virus that causes COVID-19. We found that people who had never been exposed to COVID-19 had memory T cells that worked against a specific particle of the virus, enabling them to elicit a very effective immune response against COVID-19. We also found that, when bound to HLA, this viral particle looks very similar to fragments of seasonal coronaviruses recognized by T cells. </p>
<p>Our findings suggest that <a href="https://www.nature.com/articles/s41586-023-06331-x">preexposure to seasonal cold viruses</a> allowed people with <em>HLA-B*15:01</em> to develop a very effective immune memory that helped them to quickly kill the virus before they developed symptoms. </p>
<h2>Why it matters</h2>
<p>Identifying the genetic factors associated with how the disease progresses after infection provides the basis for understanding why people respond differently to the virus that causes COVID-19 as well as other viral illnesses. Focusing on asymptomatic infections also sheds light on the early stages of infection and how the immune system fights against COVID-19. </p>
<p>Most existing vaccines protect against severe COVID-19 symptoms. Therefore, identifying the viral fragments that mediate asymptomatic infection, such as the one we discovered, can help develop more specific vaccines or therapies for COVID-19.</p>
<h2>What still isn’t known</h2>
<p>Although the genetic association we identified is strong, the immune system is very complex. It remains unclear what other mechanisms regulate asymptomatic infections, or why not everyone carrying this specific variant remains without symptoms.</p>
<h2>What’s next</h2>
<p>We want to know if the genetic variant we identified is shared by individuals from different ancestries. This will help us understand which genetic variants are important among those in these groups with asymptomatic COVID-19. We also hope to learn what makes the cross-reactive T cells in people with <em>HLA-B*15:01</em> so remarkably effective at keeping the symptoms associated with this virus at bay.</p><img src="https://counter.theconversation.com/content/209774/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jill Hollenbach receives funding from National Institutes of Health</span></em></p><p class="fine-print"><em><span>Danillo Augusto receives funding from the National Institutes of Health</span></em></p>Researchers found that people with a specific gene variant were two to eight times more likely to not have symptoms after infection.Jill Hollenbach, Professor of Neurology, University of California, San FranciscoDanillo Augusto, Assistant Professor of Biological Sciences, University of North Carolina – CharlotteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1925702022-12-08T13:32:46Z2022-12-08T13:32:46ZPeople can have food sensitivities without noticeable symptoms – long-term consumption of food allergens may lead to behavior and mood changes<figure><img src="https://images.theconversation.com/files/499637/original/file-20221207-18-b6a7kw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Asymptomatic sensitization may lead people to continue consuming food allergens, causing hidden neurological issues.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-woman-in-striped-shirt-from-back-choosing-royalty-free-image/1357286617">Garetsworkshop/iStock via Getty Images Plus</a></span></figcaption></figure><p>The prevalence of food allergies is increasing worldwide, <a href="https://doi.org/10.1111/j.1399-3038.2011.01145.x">approaching an epidemic level</a> in some regions. In the U.S. alone, <a href="https://www.foodallergy.org/resources/facts-and-statistics">approximately 10% of children and adults</a> suffer from food allergies, with allergies to cow’s milk, eggs, peanuts and tree nuts being the most common. Some patients have mild symptoms that might not need medical attention, leaving these cases unreported. </p>
<p>Food allergies, or food hypersensitivities, result from the overreaction of the immune system to typically harmless proteins in food. They can manifest as a <a href="https://acaai.org/allergies/allergic-conditions/food/">spectrum of symptoms</a>, ranging from itching, redness and swelling for milder reactions, to vomiting, diarrhea, difficulty breathing and other potentially life-threatening symptoms for severe reactions.</p>
<p>Besides self-reporting, food allergies can be <a href="https://acaai.org/allergies/testing-diagnosis/">diagnosed by exposing patients</a> to trace amounts of offending proteins, or allergens, via their mouth or skin and observing their immediate reactions. More commonly, doctors use blood tests to measure the levels of <a href="https://www.aaaai.org/tools-for-the-public/allergy,-asthma-immunology-glossary/immunoglobulin-e-(ige)-defined">immunoglobulin E, or IgE</a>, a specialized antibody that the immune system uses to identify allergens and trigger a response. Although healthy individuals may have low levels of IgE in the blood, patients with food allergies have much higher levels that increase their risk of having severe allergic reactions.</p>
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<a href="https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Patient undergoing skin-prick allergy test on arm" src="https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499636/original/file-20221207-16-gmhxjg.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">Skin-prick allergy tests involve exposing patients to trace amounts of an allergen and observing their reactions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/immunologist-doing-skin-prick-allergy-test-on-a-royalty-free-image/1288998568">ronstik/iStock via Getty Images</a></span>
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</figure>
<p>But <a href="https://doi.org/10.1159%2F000517824">some people</a> who test positive on skin-prick allergy tests with moderate increases in IgE don’t notice any allergy-related symptoms when they eat the allergen. This condition is sometimes referred to as <a href="https://www.verywellhealth.com/what-is-sensitization-82988">asymptomatic sensitization</a>. In many cases, people with this condition may not even be aware that they have a food hypersensitivity. </p>
<p>Are they truly asymptomatic, though? Or are there effects within their body that they aren’t aware of?</p>
<p>I am a <a href="https://scholar.google.com/citations?user=kXRRwk4AAAAJ&hl=en">neuroscientist</a> studying how the brain is affected by food allergies. I became interested in this topic when I found that some of my family members had a hypersensitivity to cow’s milk. Some totally avoid dairy products because they have experienced severe, life-threatening symptoms. Those who don’t have typical allergic reactions occasionally eat dairy, but appear to develop seemingly unrelated illnesses a day or two later.</p>
<p>What I and other researchers have found is that food allergens can affect your brain and behavior if you’re hypersensitized, even if you don’t have typical food allergy symptoms.</p>
<h2>Food allergies linked to behavioral disorders</h2>
<p>Researchers have suspected food hypersensitivities to be a potential cause for behavioral disorders for decades.</p>
<p>A <a href="https://doi.org/10.1097/00007611-194908000-00017">1949 case report</a> described behavioral and mood disturbances in patients after they ate certain foods, such as milk and eggs. Their symptoms improved after removing the suspected foods from their diet, suggesting that a food hypersensitivity was the likely culprit. However, I was intrigued that the patients had been able to eat the offending foods up until they chose to avoid them. In other words, they were asymptomatically sensitized, or tolerant, to the allergens.</p>
<p>Several recent studies in people have supported the association between food allergies and various neuropsychiatric disorders, including <a href="https://doi.org/10.1111/all.12829">depression, anxiety</a>, <a href="https://doi.org/10.1016/j.aller.2016.03.001">attention-deficit/hyperactivity disorder</a> and <a href="https://doi.org/10.1002/aur.2106">autism</a>. They strengthen the possibility that some reactions to food allergens could involve the nervous system and manifest as behavioral disorders.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/xyQY8a-ng6g?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The food you eat can affect your brain in many ways.</span></figcaption>
</figure>
<p>However, the idea of food hypersensitivity causing neuropsychiatric disorders is still controversial because of inconsistencies across studies. Differences in the types of allergies, ethnic backgrounds, dietary habits and other factors among the study participants can produce conflicting results. More importantly, some studies included those with self-reported food allergies, while others included only those with lab-confirmed food allergies. This limited investigations to only symptomatic individuals.</p>
<h2>Food hypersensitivity, brain and behavior</h2>
<p><a href="https://doi.org/10.1016/j.bbi.2021.03.002">My laboratory tested</a> whether food allergens could manifest as behavioral symptoms, particularly in asymptomatically sensitized individuals. We wanted to find out whether eating offending foods could lead to brain inflammation and behavioral changes after sensitization, even in the absence of other obvious severe reactions.</p>
<p>To minimize the individual differences found in human studies, we decided to work with mice. We sensitized mice of the same age and genetic background to the common milk allergen β-lactoglobulin, or BLG, and fed them the same diet in the same room. We found that while <a href="https://doi.org/10.1016/j.bbi.2021.03.002">BLG-sensitized mice</a> produced moderately but significantly elevated levels of IgE, they did not show immediate allergic reactions. They could even eat food containing the milk allergen for two weeks without showing any obvious symptoms, despite maintaining elevated levels of IgE. This indicated that they were asymptomatically sensitized.</p>
<p>We then observed whether they showed any changes in emotionally driven behavior. Because we could not ask mice how they felt, we deduced their “feelings” by noting changes from their normal, survival-oriented behavior. Mice instinctively explore their environment to search for food and shelter while avoiding potential danger. However, “anxious” mice tend to spend more time hiding to play it safe. We identified “depressed” mice by briefly holding them by the tail. Most mice will keep fighting to get out of the uncomfortable predicament, while depressed mice quickly give up.</p>
<p>Our experiments were designed to simulate situations where asymptomatically sensitized individuals would eat either a large amount of an offending food in one day or small amounts every day for a few weeks. We mimicked these situations by placing a large amount of the milk allergen directly into the stomach of sensitized mice with a feeding tube, or giving them an allergen-containing mouse chow to eat the allergen a little at a time.</p>
<p>Interestingly, BLG-sensitized mice showed <a href="https://doi.org/10.1016/j.bbi.2021.03.002">anxiety-like behavior</a> one day after receiving a large amount of the allergen. Another group of sensitized mice developed <a href="https://doi.org/10.3390/cells11040738">depression-like behavior</a> after eating small amounts of allergen for two weeks. In addition, BLG-sensitized mice showed signs of brain inflammation and neuronal damage, suggesting that changes in the brain may be responsible for their behavioral symptoms.</p>
<p>We also investigated the <a href="https://doi.org/10.3389/falgy.2022.870628">long-term effect</a> of allergen consumption by keeping BLG-sensitized mice on the allergen-containing diet for one month. We found that IgE levels declined in sensitized mice by the end of the month, indicating that continually eating small amounts of the allergen led to decreased immune responses, or “desensitization.” In contrast, signs of brain inflammation remained, suggesting that the harmful effect of allergens persisted in the brain.</p>
<h2>Chronic brain inflammation</h2>
<p>Researchers have yet to study prolonged brain inflammation, or neuroinflammation, in people who are asymptomatically sensitized. In general, though, <a href="https://doi.org/10.1172/JCI90609">chronic neuroinflammation</a> is a known contributor to neurodegenerative diseases, such as multiple sclerosis and Alzheimer’s disease, although the exact causes of these diseases are unknown. A better understanding of the role allergens play in neuroinflammation can help researchers clarify whether food allergens trigger chronic inflammation that can lead to these diseases.</p>
<p>This knowledge could be especially important for patients undergoing <a href="https://www.aaaai.org/Tools-for-the-Public/Allergy,-Asthma-Immunology-Glossary/Oral-Immunotherapy-Defined">oral immunotherapy</a>, an approach to allergy treatment that involves incrementally ingesting small amounts of allergens over time. The goal is to desensitize the immune system and reduce the incidence of anaphylaxis, or life-threatening allergic reactions. In 2020, the U.S. Food and Drug Administration <a href="https://www.fda.gov/news-events/press-announcements/fda-approves-first-drug-treatment-peanut-allergy-children">approved a standardized form of peanut allergens</a> to prevent anaphylaxis in eligible pediatric patients. However, its possible long-term effect on the nervous system is unknown.</p>
<p>Food allergens can affect the brain and behavior of seemingly asymptomatic people, making them not so asymptomatic neurologically. Considering how your brain responds to the food you eat puts a whole new meaning to the phrase “you are what you eat.”</p><img src="https://counter.theconversation.com/content/192570/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kumi Nagamoto-Combs receives funding from the National Institute of Allergy and Infectious Disease and the National Institute on Aging. </span></em></p>Food allergies have been linked to behavioral and mood disorders, including depression, anxiety and ADHD.Kumi Nagamoto-Combs, Assistant Professor of Biomedical Sciences, University of North DakotaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1462802020-09-21T19:18:24Z2020-09-21T19:18:24ZSARS-CoV-2 infection can block pain, opening up unexpected new possibilities for research into pain relief medication<figure><img src="https://images.theconversation.com/files/358898/original/file-20200919-20-bvwjcf.jpg?ixlib=rb-1.1.0&rect=74%2C52%2C4917%2C3690&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The spike protein on SARS-CoV-2 interferes with pain perception.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/runner-with-knee-pain-conceptual-royalty-free-illustration/1190785629?adppopup=true"> SEBASTIAN KAULITZKI/SCIENCE PHOTO LIBRARY/Getty Images</a></span></figcaption></figure><p>Imagine being infected with a deadly virus that makes you impervious to pain. By the time you realize you are infected, it’s already too late. You have spread it far and wide. Recent findings in my lab suggest that this scenario may be one reason that people infected with SARS-CoV-2, the virus causing COVID-19, may be spreading the disease without knowing it.</p>
<p>Most accounts to date have focused on how the virus invades cells via the <a href="https://theconversation.com/what-is-the-ace2-receptor-how-is-it-connected-to-coronavirus-and-why-might-it-be-key-to-treating-covid-19-the-experts-explain-136928">ACE2 protein</a> on the surface of many cells. But <a href="https://doi.org/10.1101/2020.06.07.137802">recent</a> <a href="https://doi.org/10.1101/2020.06.05.134114">studies</a>, which have not yet been peer-reviewed, suggest there is another route to infecting the cell that enables it to infect the nervous system. This led my research group to uncover a link between a particular cellular protein and pain – <a href="https://doi.org/10.1101/2020.07.17.209288">an interaction that is disrupted by the coronavirus</a>. Our research has now been peer-reviewed and will be <a href="https://doi.org/10.1101/2020.07.17.209288">published in the journal PAIN</a>. </p>
<p><a href="https://scholar.google.com/citations?user=lrqA5m4AAAAJ&hl=en">I am a scientist</a> who studies how proteins on cells trigger pain signals that are transmitted through the body to the brain. When these proteins are active, the nerve cells are talking to each other. This conversation occurs at deafening levels in chronic pain. So by studying what causes the excitability of nerve cells to change, we can begin to unravel how chronic pain becomes established. This also allows us to design ways to mute this conversation to blunt or stop chronic pain. </p>
<p><a href="https://www.researchgate.net/lab/Rajesh-Khanna-Lab">My laboratory</a> has a longstanding interest in designing nonopioid-based alternatives for pain management. </p>
<h2>Linking SARS-CoV-2 and pain</h2>
<p>You might be wondering how my lab began to probe the connection between SARS-CoV-2 and pain. We were inspired by <a href="https://www.biorxiv.org/content/10.1101/2020.06.07.137802v2">two</a> <a href="https://doi.org/10.1101/2020.06.05.134114">preliminary</a> reports that appeared on the preprint server BioRxiv that showed that the infamous spike proteins on the surface of the SARS-CoV-2 virus bound to a protein called neuropilin-1. This means that the virus can also use this protein to invade nerve cells <a href="https://theconversation.com/what-is-the-ace2-receptor-how-is-it-connected-to-coronavirus-and-why-might-it-be-key-to-treating-covid-19-the-experts-explain-136928">as well as through the ACE2 protein</a>.</p>
<p>For the past year, some six months before the pandemic took hold, my colleagues and I had been studying the role of neuropilin-1 in the context of pain perception. Because neuropilin-1, like the ACE2 receptor, allowed spike to enter the cells, we wondered if this alternate gateway could also be related to pain.</p>
<p>Under normal circumstances, the neuropilin-1 protein controls the growth of blood vessels, and as well as the growth and survival of neurons.</p>
<p>However, when neuropilin-1 binds to a naturally occurring protein called called Vascular endothelial growth factor A (VEGF-A), this triggers pain signals. This signal is transmitted via the spinal cord into higher brain centers to cause the sensation we all know as pain. </p>
<p>Staring at this jigsaw puzzle – neuropilin-1 and VEGF-A and neuropilin and spike – we wondered if there was a link between spike and pain. </p>
<p>Previous research has shown a link between VEGF-A and pain. For people with osteoarthritis, for instance, <a href="http://doi.org/10.1186/s12891-018-2127-2">studies have shown that increased activity of the VEGF gene</a> in fluids lubricating joints, like the knee, is associated with higher pain scores.</p>
<p>Although activity of the neuropilin-1 gene is <a href="https://doi.org/10.1101/2020.06.07.137802">higher in biological samples from COVID-19 patients compared to healthy controls</a> and activity of the neuropilin-1 gene is increased in <a href="https://doi.org/10.3389/fneur.2017.00049">pain-sensing neurons in an animal model of chronic pain</a>, the role of neuropilin-1 in pain has never been explored until now. </p>
<p>In in vitro studies done in my lab using nerve cells, we showed that when spike binds to neuropilin-1 it decreases pain signaling, which suggests that in a living animal it would also have a pain-dulling effect. </p>
<p>When the spike protein binds to the neuropilin-1 protein, it blocks the VEGF-A protein from binding and thus hijack’s a cell’s pain circuitry. This binding suppresses the excitability of pain neurons, leading to lower sensitivity to pain. </p>
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<a href="https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=146&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=146&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=146&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=183&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=183&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358243/original/file-20200915-18-s3015d.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=183&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Crystal structure of neuropilin-1 b1 domain (white surface with binding site in red) showing binding of VEGF-A (left), spike protein (middle), and the neuropilin-1 inhibitor EG00229 (right).</span>
<span class="attribution"><span class="source">Dr. Samantha Perez-Miller</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>From the COVID-19 fog a new pain target emerges</h2>
<p>If our finding that the new coronavirus is attacking cells through a protein associated with pain and disabling the protein can be confirmed in humans, it may provide a new pathway for drug development to treat COVID-19.</p>
<p><a href="https://doi.org/10.1186/s12891-018-2127-2">A small molecule, called EG00229, targeting neuropilin-1</a> had been reported in a 2018 study. This molecule binds to the same region of the neuropilin-1 protein as the viral spike protein and VEGF-A. So I and my colleagues asked if this molecule was able to block pain. It did, during pain simulations in rats. Our data reaffirmed the notion of neuropilin-1 as a new player in pain signaling. </p>
<p>There is precedence for targeting the neuropilin-1 protein for cancer treatment: for example, a <a href="https://clinicaltrials.gov/ct2/show/NCT00747734">Phase 1a clinical trial</a> of an antibody called <a href="https://www.cancer.gov/publications/dictionaries/cancer-drug/def/anti-neuropilin-1-monoclonal-antibody-mnrp1685a">MNRP1685A</a> (known under the product name Vesencumab) that recognizes and <a href="http://doi.org/10.1007/s10637-014-0071-z">binds to neuropilin-1 and blocks VEGF-binding</a>. This was mostly well tolerated in cancer patients, but it caused pain rather than blocking it. </p>
<p>Our studies identify a different approach because we targeted blocking the pain-triggering VEGF-A protein, which then resulted in pain relief. So our preclinical work described here provides a rationale for targeting the VEGF-A/NRP-1 pro-pain signaling system in future clinical trials.</p>
<p>Analysis of the structure of the neuropilin-1 receptor protein may allow design of drugs targeting this critical site which also controls axon growth, cell survival – in addition to pain relief. </p>
<p>[<em>Get facts about coronavirus and the latest research.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=coronavirus-facts">Sign up for The Conversation’s newsletter.</a>]</p>
<p>For instance, these neuropilin-1 receptor targeted drugs could potentially block viral infection. The testing of several candidate compounds, some of them on the FDA’s generally regarded as safe list, is currently underway by my group. </p>
<p>Sneaky virus, fooling people into believing that they do not have COVID-19. But, ironically, it may be gifting us with the knowledge of a new protein, critical for pain. Two roads emerge in the forest ahead: (1) block neuropilin-1 to limit SARS-CoV-2 entry, and (2) block neuropilin-1 to block pain.</p><img src="https://counter.theconversation.com/content/146280/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rajesh Khanna receives funding from NINDS and NIDA. Khanna is the co-founder of Regulonix LLC, a company developing non-opioids drugs for chronic pain. In addition, R. Khanna has patents US10287334 and US10441586 issued to Regulonix LLC. R. </span></em></p>The SARS-CoV-2 virus usually infects the body via the ACE2 protein. But there is another entry point that allows the virus to infect the nervous system and block pain perception.Rajesh Khanna, Professor of Pharmacology, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1433402020-07-30T12:50:35Z2020-07-30T12:50:35ZTest positivity rate: How this one figure explains that the US isn’t doing enough testing yet<figure><img src="https://images.theconversation.com/files/350231/original/file-20200729-15-p7dsv5.jpg?ixlib=rb-1.1.0&rect=51%2C73%2C4853%2C3196&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As cases surge, testing needs to increase as well.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Texas/f793ee6a0f9447ba9bc0c52d70422f91/59/0">AP Photo/David J. Phillip</a></span></figcaption></figure><p>The U.S. has performed <a href="https://coronavirus.jhu.edu/testing/international-comparison">more coronavirus tests</a> than any other country in the world. Yet, at the same time, the U.S. is notably underperforming in terms of suppressing COVID-19. Confirmed cases – as well as deaths – are surging in many parts of the country. Some people have argued that the increase in cases is solely due to increased testing.</p>
<p><a href="https://scholar.google.com/citations?hl=en&user=kWGF578AAAAJ">I am a statistician</a> who studies how mathematics and statistics can be used to track diseases. The claim that the increase in cases is only caused by increases in testing is just not true. But how do public health officials know this?</p>
<h2>Testing, confirmed cases and total cases</h2>
<p>COVID-19 testing has two purposes. The first is to confirm a diagnosis so that medical treatment can be appropriately rendered. The second is to do surveillance for tracking and disease suppression – including finding those who <a href="https://theconversation.com/can-people-spread-the-coronavirus-if-they-dont-have-symptoms-5-questions-answered-about-asymptomatic-covid-19-140531">may be asymptomatic</a> or only have mild symptoms – so that individuals and public health officials can take actions to slow the spread of the virus.</p>
<p>At a White House briefing on July 13, the president said, <a href="http://www.whitehouse.gov/briefings-statements/remarks-president-trump-roundtable-stakeholders-positively-impacted-law-enforcement">“When you test, you create cases.”</a> </p>
<p>The problem with this statement is that anyone who is infected with the coronavirus is, by definition, a case. Since taking a COVID-19 test does not cause a person to get coronavirus, just like taking a pregnancy test does not cause one to become pregnant, the president’s claim is false. Testing does not create cases. </p>
<p>However, because many COVID-19 cases are asymptomatic, many people are infected and don’t know it. What COVID-19 testing does do is identify unknown cases. And thus it does increase the number of cases that are known, or otherwise called the confirmed case count.</p>
<p>Finding unknown cases is good, not bad, because identifying those who are COVID-19-positive allows individuals and public health officials to take actions that slow the spread of the disease. When public health officials find cases, they can begin contact tracing. When a person finds out they are infected, they will know to quarantine. </p>
<p>Since the beginning of the pandemic, the U.S. has performed <a href="https://coronavirus.jhu.edu/testing/international-comparison">more total tests and more tests per capita than any other country</a>, though as of late July <a href="https://www.statista.com/statistics/1104645/covid19-testing-rate-select-countries-worldwide/">the U.K., Russia and Qatar were performing more tests per capita per day</a>. But counting the total number of tests or the tests per capita is not the right way to judge success of a testing program. </p>
<p>As it says on the <a href="https://coronavirus.jhu.edu/testing/international-comparison">Johns Hopkins testing comparison page</a>, a country’s “testing program should be scaled to the size of their epidemic, not the size of the population.” Sure, the U.S. might have a big testing program, but it has a massive epidemic. The U.S. needs an equally massive testing program if health officials want to have an accurate picture of what’s really going on. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&rect=38%2C49%2C3628%2C2187&q=45&auto=format&w=1000&fit=clip"><img alt="Two health care works standing outside preparing to perform a swab test at a drive-through testing station." src="https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&rect=38%2C49%2C3628%2C2187&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350218/original/file-20200729-13-lzu5vp.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">As the need for testing has grown, so have lines at testing facilities. Results can take more than a week to be returned.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Oklahoma/c533d6aa37dd4d5e8f8f84a8d052cc37/1/0">AP Photo/Sue Ogrocki</a></span>
</figcaption>
</figure>
<h2>Test positivity rate</h2>
<p>So how do public health officials know if they are doing enough testing?</p>
<p>Better than simply counting total number of tests, the test positivity rate is a useful measure of whether enough tests are being done. The test positivity rate is simply the fraction of tests that come back positive. It is calculated by dividing the number of positive tests by the total number of tests. Generally, a lower test positivity rate is good.</p>
<p>A good way to think about test positivity is to think about fishing with a net. If you catch a fish almost every time you send the net down – high test positivity - that tells you there are probably a lot of fish around that you haven’t caught – there are a lot of undetected cases. On the other hand, if you use a huge net – more testing – and only catch a fish every once in a while – low test positivity – you can be pretty sure that you’ve caught most of the fish in the area. </p>
<p>According to the World Health Organization, before a region can relax restrictions or begin reopening, the test positivity rate from a comprehensive testing program should be <a href="http://www.who.int/publications/i/item/public-health-criteria-to-adjust-public-health-and-social-measures-in-the-context-of-covid-19">at or below 5%</a> for at least 14 days.</p>
<p>There are two ways to lower a test positivity rate: either by decreasing the number of positive tests or by increasing the total number of tests. A comprehensive testing program does both. By conducting a large number of tests, most cases in the community are detected. Then, individual and government actions can be taken that contain the virus. This results in a declining number of positive tests. </p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>Returning to the fishing metaphor, the goal of a comprehensive testing program is to use a huge net to overfish in the coronavirus lake until there are very few COVID-19 cases left. Using the test positivity rate as a measure of success helps ensure that a testing program is appropriately scaled to the size of an epidemic.</p>
<p>As of July 27, the U.S. as a whole had a <a href="https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/testing-in-us.html">test positivity rate of 10%</a>. States where testing programs are robust and the virus is fairly well controlled have test positivity rates well below 5%, like <a href="https://coronavirus.jhu.edu/testing/testing-positivity">Massachusetts at 2.68% and New York at 1.09%</a>. In places like Mississippi and Arizona that are experiencing large outbreaks, <a href="https://coronavirus.jhu.edu/testing/testing-positivity">test positivity rates are above 20%</a>.</p>
<h2>The right amount of testing</h2>
<p>The increases in confirmed cases aren’t occurring just because there is more testing. The high test positivity rates in some locations show that the virus is in fact spreading and growing so testing needs to grow with it. I believe that if the U.S. wants to beat back this virus, one of the first things that needs to happen is to increase testing. We need to deploy larger nets to catch more fish. Yes, we’ll find more cases, but that’s the point.</p><img src="https://counter.theconversation.com/content/143340/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ronald D. Fricker Jr. 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>Test positivity rates measure the success of a testing program. Even though the US performs a huge number of tests, high test positivity rates across the country show that that it still isn’t enough.Ronald D. Fricker Jr., Professor of Statistics and Senior Associate Dean, Virginia TechLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1429752020-07-28T21:16:31Z2020-07-28T21:16:31ZCoronavirus outbreaks are inevitable as Ontario plans to reopen schools<figure><img src="https://images.theconversation.com/files/349934/original/file-20200728-35-1kxbm4a.jpg?ixlib=rb-1.1.0&rect=40%2C73%2C5422%2C3383&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Schoolchildren, some wearing masks, attend a class in a school of Strasbourg in eastern France in May 2020. </span> <span class="attribution"><span class="source"> (AP Photo/Jean-Francois Badias)</span></span></figcaption></figure><p>As school boards across Ontario announce they’re reopening in September, parents worry about two things: Will my children and I be safe, and will my children learn appropriately? </p>
<p>In Ontario’s large urban centres, some children will not be safe in classrooms in September. Among the returning cohort will be asymptomatic carriers of COVID-19. The science is clear that <a href="https://wwwnc.cdc.gov/eid/article/26/10/20-1315_article">asymptomatic children have unknowingly spread the virus to others in schools</a>.</p>
<p><a href="https://doi.org/10.1016/s1473-3099(20)30287-5">School children have also infected their parents</a>.</p>
<p>Otto Helve, a pediatric infectious disease expert, correctly observed: “<a href="https://www.sciencemag.org/news/2020/07/school-openings-across-globe-suggest-ways-keep-coronavirus-bay-despite-outbreaks">Outbreaks in schools are inevitable</a>.” </p>
<h2>New outbreaks despite safety measures</h2>
<p>Experience around the world confirms Helve’s point. More than <a href="https://science.sciencemag.org/content/369/6501/241.abstract">20 countries reopened schools this past spring</a>, using a variety of infection control strategies. But virus outbreaks occurred anyway; schools in <a href="https://www.nytimes.com/2020/07/18/health/coronavirus-children-schools.html">China, Israel and South Korea</a> had to close again. </p>
<p>In Germany, the proportion of children under age 19 that comprised the cluster of <a href="https://science.sciencemag.org/content/369/6501/241.abstract">new infections doubled in a two-month period</a> after schools reopened. A few countries never closed schools. <a href="https://www.theglobeandmail.com/canada/article-what-lessons-can-canadian-educators-learn-from-swedish-schools/">Virus outbreaks occurred</a>. </p>
<figure class="align-center ">
<img alt="A teenager tries on a face shield with a full face visor as a classmate stands behind him smiling." src="https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349940/original/file-20200728-29-15ij4sc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A student tries out a new face shield to fight the coronavirus pandemic at a school in Cologne, Germany, in May 2020. (AP Photo/Martin Meissner)</span>
<span class="attribution"><span class="source">(AP Photo/Martin Meissner)</span></span>
</figcaption>
</figure>
<p>Canada’s experience is similar. A reopened elementary school in Trois-Rivières, Québec, had <a href="https://montrealgazette.com/news/coronavirus-infects-nine-of-11-students-in-trois-rivieres-classroom">nine of 11 students infected</a> after one contracted the virus, despite using prevention measures. <a href="https://www.cbc.ca/news/canada/british-columbia/bc-covid-19-update-june-25-1.5627324">COVID-19 appeared in British Columbia schools</a> after they reopened in June. Similar outbreaks occurred in daycare centres <a href="https://www.thestar.com/opinion/2020/04/29/quebec-is-taking-a-terrible-risk-by-sending-children-back-to-school.html">outside of Toronto</a> <a href="https://montreal.ctvnews.ca/16-infected-north-of-montreal-in-quebec-s-first-covid-19-outbreak-in-a-daycare-1.4927853?cache=qpcupizl%3FclipId%3D89531">and Montréal</a>. </p>
<p>The Ottawa School Board proposed to the province to reopen its 72 schools five days a week in September. Dr. Vera Etches, Ottawa’s medical officer of health, supported the board. <a href="https://www.glengower.ca/information/july-10-special-statement-from-dr-vera-etches/">She recommended</a> “starting with five days of school in-person and working to make this as safe as possible through reasonable and feasible infection prevention and control measures ….”</p>
<h2>Unsafe premise</h2>
<p>The error of Dr. Etches’ analysis begins with an unsafe premise — schools must reopen in September. </p>
<p>The first question should be whether schools can implement <a href="https://www.cdc.gov/coronavirus/2019-ncov/community/schools-childcare/schools.html">public health measures</a> by September that will reduce risk of virus outbreaks to acceptable proportions. The answer to that question in many Ontario municipalities is no. </p>
<p>The <a href="http://www.iiep.unesco.org/en/plan-school-reopening">human, physical and financial resources required</a> to contain <a href="https://www.nytimes.com/2020/07/18/health/coronavirus-children-schools.html">the inevitable</a> outbreaks are large, complicated, contested and not in place. Time is necessary to plan, organize and implement. Time ran out months ago.</p>
<figure class="align-center ">
<img alt="Desks, chairs and shelving units are pushed against the wall of an empty corridor in a school." src="https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349941/original/file-20200728-35-h7b8ck.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">Furniture sits in an empty corridor at a school in Brampton, Ont., on July 23, 2020.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Chris Young</span></span>
</figcaption>
</figure>
<h2>Ontario’s reopening plan</h2>
<p>Ontario <a href="https://news.ontario.ca/opo/en/2020/07/ontario-releases-plan-for-safe-reopening-of-schools-in-september.html">announced</a> <a href="https://www.ontario.ca/page/guide-reopening-ontarios-schools#section-1">its plan</a> to reopen schools on July 30. </p>
<p>Elementary and some secondary schools will reopen with in-class instruction five days a week. Secondary students in 24 designated boards — mainly in urban and high enrolment suburban areas — will attend school in cohorts of up to 15, alternating between in-person days and online study. </p>
<p>Ontario will spend $309 million on its plan, mostly for purchasing personal protective and medical equipment, nursing services and for cleaning of schools and buses; $30 million of this is for hiring teachers to support the smaller classes.</p>
<p>The plan’s safety measures are not robust. Most Ontario schools cannot support two-metre distancing. Ontario, accordingly, is requiring only <a href="https://www.ontario.ca/page/guide-reopening-ontarios-schools#section-4">“as much distancing as possible.”</a> </p>
<p>Students to Grade 3 are not required to wear masks. Plexiglass shields will not be installed to deal with the inability to distance students or impose masking requirements on them. There will be no substantial renovations to school buildings to make schools as safe as possible.</p>
<p>Ontario’s plan requires staff and students to self-screen for the virus every day. Schools will not do the testing.</p>
<p>The province took a hard decision in an area fraught with uncertainty. This much, however, is sure. Outbreaks of the virus will occur in the reopened schools. Asymptomatic carriers among the returnees will transmit the virus to their classmates, parents and teachers. </p>
<p>Whether the outbreaks will be contained with isolation and contact tracing, or rage out of control – Florida-like – imperilling whole communities, nobody knows. It’s not inaccurate to consider the plan an experiment.</p>
<h2>Reopen in January at the earliest</h2>
<p>Ontario should delay reopening schools until January or September 2021. The province should put school boards to work now renovating schools for the best possible safety protocols. Ontario should not experiment with our children.</p>
<p>Ontario should also work with the federal government to develop resources to test each child for the virus every day. Several companies and academic laboratories are <a href="https://www.nytimes.com/2020/07/03/opinion/coronavirus-tests.html">developing easy-to-use diagnostic tests</a> that could be used by schools, including a spit-test that looks for traces of SARS-CoV-2, the virus that causes COVID-19. Federal and provincial governments should organize, fund and fast-track getting this, and similar tests, into schools for January or September 2021.</p>
<h2>Invest in remote learning now</h2>
<p><a href="https://lfpress.com/news/local-news/covid-19-ontarios-forced-foray-into-remote-learning-offers-lasting-lessons-experts-say">Ontario boards failed woefully</a> to educate students online from <a href="https://ocdsb.ca/cms/One.aspx?portalId=55478&pageId=32689595#Survey%20Responses%20from%20Parents/Guardians">March through June</a>. Since Ontario’s plan contains no new measures to improve the education children will get online, this failure will simply continue in many secondary schools. The plan will also compromise face-to-face education in these schools by deleting 50 per cent of their in-person instruction.</p>
<p>Ontario should invest heavily now in remote education. <a href="https://thebestschools.org/magazine/online-education-history/">Remote learning is a relatively new science</a> that arose out of a revolution in educational theory and produced distinctive educational practices. It is interactive, student-centred, digital — altogether different from reproducing existing classroom practices online, as occurred from March through June.</p>
<p>For remote learning, Ontario’s plan invites students to tune into <a href="https://ilc.tvo.org/en-ca/home">TVO’s Independent Learning Centre</a> and attend its menu of courses. It also instructs teachers to upload materials onto a specialized online platform. This is insufficient. </p>
<p>Specialists are needed to help teachers transform their courses into proper remote formats. These need to be hired, tech resources for universal and equal access must be purchased and people trained how to use them. Educators and staff should be trained in remote learning techniques. </p>
<p>Ontario’s plan does not devote dollars to any of this. It leaves teachers to fend for themselves. It also leaves families adrift, anticipating, for example, that <a href="https://www.ontario.ca/page/guide-reopening-ontarios-schools#section-4">“families with multiple children may need to take turns using the family’s devices or broadband access.”</a></p>
<h2>Teachers, students, families need support</h2>
<p>Teachers cannot become experts at remote education on their own. Students need help to adapt to the student-centred practices of remote techniques. And families need support.</p>
<p>Remote teaching, done properly, could allow children to learn appropriately. Good remote teaching, which should be the province’s priority, will not happen by ordering teachers to upload materials or students to watch TVO.</p>
<p>An ecosystem of good remote teaching will be created by training, support, resources and leadership to nudge the cumbersome educational system into a new direction. These pieces are missing from Ontario’s plan.</p>
<p><a href="https://www.tonybates.ca/2020/07/04/what-have-we-learned-from-covid-19-about-the-limitations-of-online-learning/">Remote teaching, even of superior quality, does not replace the social experiences children get in school</a> or the care-giving relief schools provide for working parents.</p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/students-in-melbourne-will-go-back-to-remote-schooling-heres-what-we-learnt-last-time-and-how-to-make-it-better-142550">Students in Melbourne will go back to remote schooling. Here's what we learnt last time and how to make it better</a>
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<p>Children should return to school when the virus is sufficiently under control in their community and their school is made safe. Until then — which will not be this September — Ontario should concentrate on providing leadership and resources to make schools safe and enable superior remote learning.</p>
<p>The investments made now will pay back for years to come as elementary and secondary education is transformed.</p>
<p>We have in front of us a challenge and an opportunity, both of monumental importance. We have tens of thousands of great teachers waiting to rise to the challenge. Ontario should empower them to seize the opportunity.</p><img src="https://counter.theconversation.com/content/142975/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joseph Magnet 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>Just as in other countries, COVID-19 outbreaks are a matter of when, not if, should Ontario schools reopen in September.Joseph Magnet, Professor of Law, L’Université d’Ottawa/University of OttawaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1423662020-07-24T12:29:14Z2020-07-24T12:29:14ZMaking coronavirus testing easy, accurate and fast is critical to ending the pandemic – the US response is falling far short<figure><img src="https://images.theconversation.com/files/349199/original/file-20200723-29-15bhm4z.jpg?ixlib=rb-1.1.0&rect=22%2C66%2C2880%2C1727&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are functional tests for coronavirus, but not enough of them are being done. </span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Michigan/2bf9018fca3b44a7a46d6f96d48dfbde/14/0">AP Photo/Paul Sancya</a></span></figcaption></figure><p>For many people in the U.S., getting tested for COVID-19 is a struggle. In Arizona, testing sites have seen lines of hundreds of cars <a href="https://www.msn.com/en-us/weather/topstories/people-wait-in-hours-long-line-for-free-covid-19-test-in-south-phoenix/ar-BB16gAuv">stretching over a mile</a>. In Texas and Florida, some people were <a href="https://www.bloomberg.com/news/articles/2020-06-29/in-hot-spot-states-those-seeking-tests-meet-long-lines-delays">waiting for five hours</a> for free testing. </p>
<p>The inconvenience of these long waits alone <a href="https://www.washingtonpost.com/health/long-delays-in-getting-test-results-hobble-coronavirus-response/2020/07/12/d32f7fa8-c1fe-11ea-b4f6-cb39cd8940fb_story.html">discourages many people from getting tested</a>. With the surge in cases, many public testing sites have been <a href="https://www.texastribune.org/2020/06/29/coronavirus-testing-austin-dallas-houston/">reaching maximum capacity</a> within hours of opening, leaving many people unable to get tested for days. Those that do get tested often face a week-long wait to get their test results. </p>
<p>Every person who isn’t tested could be spreading COVID-19 unknowingly. These overstretched testing programs are a weak link in the U.S. pandemic response.</p>
<p>I <a href="https://publicpolicy.umbc.edu/zoe-m-mclaren/">study public health policy</a> to combat infectious disease epidemics. The key to overcoming this pandemic is to slow transmission of the virus by preventing contagious people from infecting others. A widespread quarantine would accomplish this, but is economically and socially burdensome. Testing offers a way to identify contagious people so they can be isolated to prevent the spread of the disease. This is especially important for COVID-19 because an estimated 40% or more of all people infected with SARS-CoV-2 <a href="https://theconversation.com/can-people-spread-the-coronavirus-if-they-dont-have-symptoms-5-questions-answered-about-asymptomatic-covid-19-140531">have few or no symptoms</a> so testing is the only way to identify them.</p>
<p>Some states are doing much better than others. But as a whole, the U.S. is falling far short of the amount of testing needed to control the pandemic. What are the challenges the U.S. is facing? And what is the way forward?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A lab technician using a swab to put a sample into a rapid test machine." src="https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349203/original/file-20200723-29-112ztr1.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">Currently, rapid tests that take about 15 minutes to process are a quick and easy way to diagnose COVID-19 infections, but there are concerns about accuracy.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Testing-Problem/73ae28797e4845a8a138a38641821b12/1/0">AP Photo/Carlos Osorio</a></span>
</figcaption>
</figure>
<h2>Testing should be free, easy, fast and accurate</h2>
<p>The ultimate goal of testing is for everyone, regardless of symptoms, to know at all times whether they are infected with the coronavirus. To achieve this level of testing, tests should be free, very easy to perform and provide accurate results quickly.</p>
<p>Ideally, free COVID-19 tests would be delivered to everyone directly. The tests would be simple to perform – like a <a href="https://www.the-scientist.com/news-opinion/saliva-tests-how-they-work-and-what-they-bring-to-covid-19-67720">saliva test</a> – and would give a perfectly accurate result within minutes. Everyone could test themselves weekly or anytime they were going to be in close contact with other people.</p>
<p>In this ideal scenario, most, if not all, contagious people would be detected before they could spread the virus to others. And because of the rapid results, there would be no burden of quarantining between doing the test and getting the result.</p>
<p>Researchers are working on better-quality tests, but access is a problem of infrastructure, not science. Right now, nowhere in the U.S. comes close to meeting surging demand for testing.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A line of people waiting in cars in front of a sign for COVID-19 testing." src="https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/348981/original/file-20200722-24-y4f7xu.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">Long lines, slow turnaround times for results and shortages of testing capacity all make Texas one of the worst places to get a test in the U.S.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Texas/bf4c1e3e3ade4acb975e957da9df6fb2/7/0">AP Photo/David J. Phillip</a></span>
</figcaption>
</figure>
<h2>One of the worst cases: Texas</h2>
<p>The difficulty of getting a COVID-19 test varies by state, but currently, people in <a href="https://coronavirus.jhu.edu/testing/individual-states/texas">Texas face some of the biggest obstacles</a>, which results in far fewer tests being done than is needed to control the pandemic.</p>
<p>First, Houston – which is <a href="https://www.nytimes.com/interactive/2020/us/texas-coronavirus-cases.html">experiencing a surge in cases</a> – and <a href="https://txdps.maps.arcgis.com/apps/webappviewer/index.html?id=8bf7c6a436a64bfe9a5ce25be580e4ff">many testing sites across the state</a> <a href="https://covcheck.hctx.net/">recommend or offer testing</a> only to people who have symptoms, were exposed to a COVID-19 case or are a member of a high-risk group.</p>
<p>Even people recommended for testing still face challenges. It is possible to request an appointment for a free COVID-19 test, but testing facilities can handle only so many patients a day and testing slots <a href="https://covcheck.hctx.net/">fill up quickly</a>. Even if someone gets an appointment, they may face an hours-long wait at the testing site.</p>
<p>Finally, public health experts recommend that people who may have been exposed to COVID-19 should <a href="https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/quarantine.html">quarantine at home</a> for 14 days or until they receive a negative test result. In Texas, patients are supposed to get results through an <a href="https://publichealth.harriscountytx.gov/Resources/2019-Novel-Coronavirus/COVID-19-Testing-Information">online portal in three to five days</a>, but many labs have been <a href="https://www.dallasnews.com/news/politics/2020/06/30/overwhelming-demand-for-covid-19-tests-long-waits-for-results-hamper-texas-effort-to-control-spread/">taking seven to nine days to return results</a>. These long delays mean people face a much higher burden of quarantining while waiting for results.</p>
<p>All of these challenges make it clear that Texas is <a href="https://coronavirus.jhu.edu/testing/individual-states/texas">simply not testing enough people</a> to keep the spread of COVID-19 in check.</p>
<p>To gauge the success of COVID-19 testing programs, epidemiologists use a measure called <a href="https://coronavirus.jhu.edu/testing/testing-positivity">test positivity</a>. This is simply the percentage of tests that come back positive. The lower the test positivity, the better, because that means very few cases are going undetected. A high test-positivity rate is usually a sign that only the sickest people are getting tested and many cases are being missed.</p>
<p>The <a href="https://www.who.int/publications/i/item/public-health-criteria-to-adjust-public-health-and-social-measures-in-the-context-of-covid-19">World Health Organization guidelines</a> say that if more than 1 out of 20 COVID-19 tests comes back positive – a test positivity of more than 5% – this is an indication that a lot of cases are not diagnosed and the epidemic is not under control. <a href="https://coronavirus.jhu.edu/testing/individual-states/texas">Texas currently has a test-positivity of around 16%</a>, which means that a lot of infected people are not getting tested and may be unknowingly spreading the disease.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A doctor using a nasal swab to test a state senator of New Mexico." src="https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/348982/original/file-20200722-16-1syzk3.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">In New Mexico, it is relatively easy to get a test, so more people are getting tested.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-New-Mexico/59c51760719c4ba9b9f72e583f143427/41/0">AP Photo/Cedar Attanasio</a></span>
</figcaption>
</figure>
<h2>One of the best cases: New Mexico</h2>
<p>In stark contrast to Texas is New Mexico, which has one of the strongest testing programs in the U.S. </p>
<p>First, public health officials there encourage everyone to get tested for COVID-19 <a href="https://cv.nmhealth.org/public-health-screening-and-testing/location-details/">regardless of symptoms or exposure</a>. The state has also prohibited health providers from charging patients for tests. People seeking a test have the option to walk in or to make an appointment ahead of time, whichever is more convenient. </p>
<p>All of this relatively good access to testing has resulted in one of the <a href="https://coronavirus.jhu.edu/testing/states-comparison">highest per capita testing rates</a> in the country, at over 20,000 tests per 100,000 people, and a <a href="https://coronavirus.jhu.edu/testing/testing-positivity">test-positivity rate of around 4%</a>. New Mexico’s testing program is diagnosing a relatively high proportion of cases despite the state experiencing a recent surge.</p>
<p>[<em><a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=experts">Expertise in your inbox. Sign up for The Conversation’s newsletter and get expert takes on today’s news, every day.</a></em>]</p>
<p>New Mexico still has room for improvement. <a href="https://www.kob.com/albuquerque-news/demand-surges-for-covid-19-testing-result-times-vary-by-location/5789494/">Long lines, wait times and limited capacity</a> are becoming more common as cases surge, but the foundation of a strong testing program has helped the state cope with the increase in cases.</p>
<h2>The big-picture problems</h2>
<p>The pre-pandemic infectious disease testing capabilities in the U.S. are clearly unable to meet the current demand. A nationwide response is needed, and there are three things that Congress, the federal government and local governments can do to help ensure COVID-19 tests will be easy to get, fast and accurate. </p>
<p>First, Congress can <a href="https://www.cnn.com/2020/07/21/politics/congress-coronavirus-testing-unspent-funds/index.html">provide funding</a> to stimulate the testing supply chain, scale up existing testing programs and promote innovation in test development. Second, governments can <a href="https://www.rockefellerfoundation.org/national-covid-19-testing-action-plan/">improve the management and coordination</a> of testing programs to <a href="https://www.statnews.com/2020/04/16/fda-changes-coronavirus-testing-swabs/">more efficiently use existing resources</a>. And third, innovative testing methods that reduce the need for lab capacity – like <a href="https://www.nytimes.com/2020/07/03/opinion/coronavirus-tests.html">paper-strip tests</a> and <a href="https://theconversation.com/group-testing-for-coronavirus-called-pooled-testing-could-be-the-fastest-and-cheapest-way-to-increase-screening-nationwide-141579">pooled testing</a> – need be approved and implemented more quickly. </p>
<p>Every little improvement in testing capabilities means more COVID-19 cases can be caught before the virus is transmitted. And slowing the spread of the virus is the key to overcoming the pandemic.</p><img src="https://counter.theconversation.com/content/142366/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zoë McLaren 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>Ideally everyone could get tested frequently for the coronavirus. No state is close to achieving this, but some are doing better than others. What are the challenges in meeting demand for testing?Zoë McLaren, Associate Professor of Public Policy, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1411542020-06-25T13:49:36Z2020-06-25T13:49:36ZCoronavirus: asymptomatic people can still develop lung damage<figure><img src="https://images.theconversation.com/files/344011/original/file-20200625-33557-1jiy7fu.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C9927%2C4851&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/young-man-wearing-mask-participating-protest-1684314403">Jacob Lund/Shutterstock</a></span></figcaption></figure><p>Modern medicine rightly emphasises the importance of science. The focus, however, too often displaces our attention from the real point of healthcare – to care. This is nicely captured by William Osler’s (1849-1919) admonition to attend to the patient rather than their disease – a sentiment treated as a quaint bromide by the unwary practitioner. I rediscovered the truth of his advice when two particular patients taught me about COVID-19 infection and challenged what expertise I thought I had in managing pneumonia. </p>
<p>The first patient with COVID-19 that presented to my hospital was probably typical of initial patients in many other hospitals at the time. He was an elderly man with pneumonia, as yet untested for the new coronavirus but presumed to have it. An expert team carefully assessed him, prescribed high-flow oxygen and monitored him on a respiratory ward. He died unexpectedly that night. </p>
<p>The second patient was a middle-aged woman referred to the intensive care unit for mechanical ventilation. The recent death had made me nervous, so I went to assess her. On my way to the ward, I imagined the picture that awaited me – a patient gasping for air, barely able to speak, chest heaving with the effort of trying to drive oxygen into her blood.</p>
<p>When I arrived decked out in full PPE and ready to sedate her for immediate ventilation, I thought I had arrived at the wrong bed. She sat comfortably on her chair, speaking on her mobile phone to her daughter, bemused by my appearance. Overcautious colleagues, I thought, but measured her blood oxygen saturation just in case, more from instinct than concern. From her appearance I expected it to be close to normal (100%). It was 75% – a level barely compatible with being conscious. </p>
<h2>Silent lung damage</h2>
<p>I quickly learned that many patients with advanced COVID-19 disease bore none of the hallmarks of severe respiratory illness until they suddenly collapsed and died. The science behind this early lesson is now emerging, with a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152865/">study from Wuhan</a>, China, describing pathological lung changes on CT scans of completely asymptomatic patients. Asymptomatic carriage is not uncommon in other virulent infections, such as MRSA and <em>C diff</em>, but what is striking with SARS-CoV-2 (the virus that causes COVID-19) is that it may be accompanied by underlying organ damage.</p>
<p>The researchers found lesions consistent with inflammation of the underlying lung tissue (ground-glass opacities and consolidation, to use the medical jargon), which are not specific to SARS-CoV-2 infection and may be seen in many other forms of lung disease. What remains a mystery is why, despite these changes, patients do not display typical symptoms of pneumonia, such as severe shortness of breath. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343474/original/file-20200623-188926-1dcdalr.jpg?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">CT scan showing ground-glass opacity.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=9951501">Mluisamtz11/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>About a quarter of the patients in the study developed a fever, cough and shortness of breath – but many did not. The idiosyncratic response to infection is one of several conundrums of COVID-19, such as why it targets certain groups and not others – two people with exactly the same demography and health may express the disease at opposite ends of the spectrum. The study reinforces that absence of symptoms does not imply the absence of harm. </p>
<h2>The risks</h2>
<p>Lack of symptoms in the face of active pathology carries a risk both to infected individuals and to the public. Current advice encourages patients to stay at home if they are asymptomatic, making late presentation to hospital and sudden death a distinct risk. </p>
<p>And then there is the public health nightmare. As many as 40-45% of people infected with SARS-CoV-2 <a href="https://www.acpjournals.org/doi/10.7326/M20-3012">remain asymptomatic</a>, with a viral load as high as those who are actively ill. Add to that the significant <a href="https://www.acpjournals.org/doi/10.7326/M20-1495">false-negative rate</a> of up to 20% for screening tests – where people are wrongly told they don’t have the infection – and the scale of the problem is magnified. These are the covert transmitters who continue to shed the virus for up to 14 days and it raises clear questions about the effectiveness of the testing strategy or the use of screening measures such as temperature checking. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=753&fit=crop&dpr=1 600w, https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=753&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=753&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=947&fit=crop&dpr=1 754w, https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=947&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/344007/original/file-20200625-33557-1nuy17y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=947&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">William Osler, one of the founders of Johns Hopkins Hospital.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=7405477">Gilbert and Bacon/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>Fragments of evidence are slowly being pieced together, mainly from many small, disparate studies. The full picture will coalesce as the quality and quantity of evidence expand and refines our understanding of SARS-CoV-2. However, science still falls short of informing doctors about how to best manage the patient before them. </p>
<p>Lesions on a CT scan cannot determine what treatment is needed. It still requires a personalised decision based on clinical judgement. So even as scientific understanding grows, I will apply Osler’s advice with renewed conviction: attend to your patient with all five senses at full alert. They will teach you what you need to know.</p><img src="https://counter.theconversation.com/content/141154/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Kinnear 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>CT scans reveal lung damage in people with no symptoms.John Kinnear, Head of School of Medicine, Anglia Ruskin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1405312020-06-23T12:22:13Z2020-06-23T12:22:13ZCan people spread the coronavirus if they don’t have symptoms? 5 questions answered about asymptomatic COVID-19<figure><img src="https://images.theconversation.com/files/343262/original/file-20200622-55021-11v65vi.jpg?ixlib=rb-1.1.0&rect=49%2C0%2C4048%2C2666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Screening for symptoms can catch some cases of COVID-19, but about people who are infected but not showing any symptoms?</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Florida/f704cb34d106476c8365e80ff67db75c/1/0">AP Photo/John Raoux</a></span></figcaption></figure><p><em>Editor’s note: Screening for symptoms of COVID-19 and self-quarantine are good at preventing sick people from spreading the coronavirus. But more and more evidence is suggesting that people without symptoms are spreading the virus too. Monica Gandhi, an <a href="https://profiles.ucsf.edu/monica.gandhi">infectious diseases physician and researcher</a> at the University of California, San Francisco, explains what is known about asymptomatic spread and why she thinks it may be a big part of what is driving the pandemic.</em> </p>
<h2>What does it mean to be asymptomatic?</h2>
<p>SARS-CoV-2 – the virus that causes COVID-19 – can produce a range of clinical manifestations. </p>
<p>Some people who are infected never develop any symptoms at all. These patients are considered true asymptomatic cases.</p>
<p>When people do get sick from the coronavirus, it takes on average <a href="https://doi.org/10.7326/M20-0504">five days and as many as two weeks</a> to develop symptoms that can range from <a href="https://doi.org/10.1056/NEJMcp2009249">very mild</a> to extremely dangerous. The time between initial infection and the first symptoms is called the pre-symptomatic phase.</p>
<p>As an infectious disease physician, when I hear about asymptomatic spread of SARS-CoV-2, I think of a person who doesn’t have symptoms at the moment they give the virus to someone else. It doesn’t matter whether they are a true asymptomatic case or just pre-symptomatic; the public health risk is the same.</p>
<h2>How many people are asymptomatic?</h2>
<p>Estimates of the proportion of true asymptomatic cases – those who are infected and never develop symptoms – range <a href="https://dx.doi.org/10.2807%2F1560-7917.ES.2020.25.10.2000180">from 18%</a> to <a href="http://dx.doi.org/10.1136/thoraxjnl-2020-215091">over 80%</a>. The reasons for the huge range in estimates are still unclear, but some studies are better than others.</p>
<p>The most accurate way to determine the rate of asymptomatic cases is to test people regardless of whether or not they have symptoms – an approach called universal mass testing – and track them over time to see if they develop symptoms later. A recent mass testing campaign in San Francisco found that 53% of infected patients were asymptomatic when first tested and <a href="https://doi.org/10.1101/2020.06.15.20132233">42% stayed asymptomatic over the next two weeks</a>. </p>
<p>Another recent paper compared the evidence from 16 studies and estimated the overall rate of asymptomatic infection <a href="https://doi.org/10.7326/M20-3012">to be 40%-45%</a>. This is in line with the San Francisco finding, but the studies sampled were of various quality and size and likely include some pre-symptomatic cases.</p>
<p>Though none of these studies is perfect, a lot of evidence supports a true asymptomatic rate of around 40%, plus some addition fraction of patients who are pre-symptomatic.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343267/original/file-20200622-55009-10z69dd.jpg?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"></a>
<figcaption>
<span class="caption">Many places are asking people with COVID-19 symptoms to stay away, but people who are infected and don’t have symptoms are unlikely to realize they have the virus.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/attention-all-contractors-or-vendors-must-sign-in-warning-news-photo/1224149862?adppopup=true">Education Images/ Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<h2>How can asymptomatic people spread the coronavirus?</h2>
<p>Compared to most other viral infections, SARS-CoV-2 produces an unusually high level of viral particles in <a href="https://doi.org/10.1038/s41586-020-2196-x">the upper respiratory tract</a> – <a href="https://doi.org/10.1093/cid/ciaa345">specifically the nose and mouth</a>. When those viral particles escape into the environment, that is called viral shedding. </p>
<p>Researchers have found that pre-symptomatic people <a href="https://doi.org/0.1056/NEJMoa2008457">shed the virus at an extremely high rate</a>, similar to the seasonal flu. But people with the flu don’t normally shed virus <a href="https://doi.org/10.1093/cid/ciw841">until they have symptoms</a>. </p>
<p>The location of the shedding is also important. SARS-CoV – the virus that caused the SARS epidemic in 2003 – does not shed very much from the nose and mouth. It <a href="https://doi.org/10.1016/s0140-6736(04)16255-7">replicates deep in the lungs</a>. Since SARS-CoV-2 is present in high numbers in a person’s nose and mouth, it is that much easier for the virus to escape into the environment. </p>
<p>When people cough or talk, they <a href="https://doi.org/10.1056/NEJMc2007800">spray droplets of saliva and mucus into the air</a>. Since SARS-CoV-2 sheds so heavily in the nose and mouth, these droplets are likely how people without symptoms are spreading the virus. </p>
<h2>How much asymptomatic spread is happening?</h2>
<p>Public health experts don’t know exactly how much spread is caused by asymptomatic or pre-symptomatic patients. But there are some telling hints that it is a major driver of this pandemic. </p>
<p>An early modeling estimate suggested that <a href="https://doi.org/10.1126/science.abb3221">80% of infections could be attributed to spread from undocumented cases</a>. Presumably the undocumented patients were asymptomatic or had only extremely mild symptoms. Though interesting, the researchers made a lot of assumptions in that model so it is hard to judge the accuracy of that prediction.</p>
<p>A study looking at outbreaks in Ningbo, China, found that people without symptoms spread the virus <a href="http://doi.org/10.2196/19464">as easily as those with symptoms</a>. If half of all infected people are without symptoms at any point in time, and those people can transmit SARS-CoV-2 as easily as symptomatic patients, it is safe to assume a huge percentage of spread comes from people without symptoms. </p>
<p>Even without knowing the exact numbers, the Centers for Disease Control and Prevention believes that transmission from people without symptoms <a href="https://wwwnc.cdc.gov/eid/article/26/7/20-1595_article">is a major contributor</a> to the rapid spread of SARS-CoV-2 around the world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343269/original/file-20200622-54993-1j5lizi.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">Preventative measures, specifically universal mask wearing, are the best ways to limit asymptomatic spread.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/man-exits-a-shoe-city-store-where-masks-are-required-for-news-photo/1215627800?adppopup=true">David McNew / Stringer / Getty Images News via Getty Images</a></span>
</figcaption>
</figure>
<h2>What can we do to limit asymptomatic spread?</h2>
<p>Any time a virus can be spread by people without symptoms, you have to turn to preventative measures.</p>
<p><a href="http://doi.org/10.1001/jama.2020.6572">Social distancing measures and lockdowns work</a>, but have large economic and <a href="https://theconversation.com/quarantine-bubbles-when-done-right-limit-coronavirus-risk-and-help-fight-loneliness-140134">social repercussions</a>. These were necessary when epidemiologists didn’t know how the virus was spreading, but now we know it sheds at high quantities from the upper respiratory tract. </p>
<p>This means that universal mask wearing is <a href="https://theconversation.com/masks-help-stop-the-spread-of-coronavirus-the-science-is-simple-and-im-one-of-100-experts-urging-governors-to-require-public-mask-wearing-138507">best tool to limit transmission</a>, and there is <a href="https://doi.org/10.1098/rspa.2020.0376">evidence to back that idea up</a>. </p>
<p>On April 3, the CDC recommended that all members of the public wear facial coverings when <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover.html">outside of the house and around others</a>. The World Health Organization finally followed suit and <a href="https://apps.who.int/iris/handle/10665/332293">recommended universal public masking on June 5</a>. </p>
<p>At this point, no one knows exactly how many cases of COVID-19 are from asymptomatic spread. But I and many other infectious diseases researchers are convinced that it is <a href="https://doi.org/10.1056/NEJMe2009758">playing a major role in this pandemic</a>. Wearing a mask and practicing social distancing can prevent asymptomatic spread and help reduce the harm from this dangerous virus until we get a vaccine. </p>
<p>[<em>You need to understand the coronavirus pandemic, and we can help.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-help">Read The Conversation’s newsletter</a>.]</p><img src="https://counter.theconversation.com/content/140531/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monica Gandhi receives funding from the National Institutes of Health for HIV-related research.</span></em></p>There is a lot of confusion and concern around asymptomatic spread of SARS-C0V-2. An infectious disease expert explains how many people are asymptomatic and how they can spread the virus.Monica Gandhi, Professor of Medicine, Division of HIV, Infectious Diseases and Global Medicine, University of California, San FranciscoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1385072020-05-14T12:03:18Z2020-05-14T12:03:18ZMasks help stop the spread of coronavirus – the science is simple and I’m one of 100 experts urging governors to require public mask-wearing<figure><img src="https://images.theconversation.com/files/334836/original/file-20200513-156665-65xuab.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Evidence is growing that when masks are worn by nearly everyone, it can slow coronavirus transmission.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Utah/f9d15295f92845e68b31c0e5df09bb98/36/0">AP Photo/Rick Bowmer</a></span></figcaption></figure><p>I’m a <a href="https://www.usfca.edu/faculty/jeremy-howard">data scientist</a> at the University of San Francisco and teach courses online in machine learning for <a href="https://www.fast.ai/">fast.ai</a>. In late March, I decided to use public mask-wearing as a case study to show my students how to combine and analyze diverse types of data and evidence.</p>
<p>Much to my surprise, I discovered that the evidence for wearing masks in public was very strong. It appeared that universal mask-wearing could be one of the most important tools in tackling the spread of COVID-19. Yet the people around me weren’t wearing masks and health organizations in the U.S. weren’t recommending their use. </p>
<p>I, along with 18 other experts from a variety of disciplines, conducted a review of the research on public mask-wearing as a tool to slow the spread SARS-CoV-2. We published a preprint of <a href="https://doi.org/10.20944/preprints202004.0203.v2">our paper</a> on April 12 and it is now awaiting peer review at the <a href="https://www.pnas.org/">Proceedings of the National Academy of Sciences</a>. </p>
<p>Since then, there have been <a href="https://doi.org/10.1111/resp.13834">many</a> <a href="https://doi.org/10.1093/jtm/taaa056">more</a> reviews that support mask-wearing.</p>
<p>On May 14, I and 100 of the world’s top academics released an <a href="https://masks4all.co/letter-over-100-prominent-health-experts-call-for-cloth-mask-requirements/">open letter</a> to all U.S. governors asking that “officials <em>require</em> cloth masks to be worn in all public places, such as stores, transportation systems, and public buildings.” </p>
<p>Currently, the U.S. Centers for Disease Control and Prevention recommends that everyone wears a mask – as do the governments covering 90% of the world’s population – but, so far, only 12 states in the U.S. require it. In the majority of the remaining states, the CDC recommendation has not been enough: Most people <a href="http://www.kateto.net/COVID19%20CONSORTIUM%20REPORT%20April%202020.pdf">do not currently wear masks</a>. However, things are changing fast. Every week more and more jurisdictions require mask use in public. As I write this, there are now <a href="https://airtable.com/shreZdkFaYZqfpEqU/tbl5o6qUd54BL9wkw">94 countries</a> that have made this move.</p>
<p>So what is this evidence that has led myself and so many scientists to believe so strongly in masks?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334823/original/file-20200513-156675-1cpet7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Droplets ejected from people’s mouths during coughing or talking are likely the most significant source of SARS-CoV-2 transmission.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/man-exhaling-vapor-side-view-close-up-night-royalty-free-image/200340020-002?adppopup=true">Thomas Jackson/Stone via Getty Images</a></span>
</figcaption>
</figure>
<h2>The evidence</h2>
<p>The research that first convinced me was a <a href="https://doi.org/10.1056/NEJMc2007800">laser light-scattering experiment</a>. Researchers from the <a href="https://www.nih.gov/">National Institutes of Health</a> used lasers to illuminate and count how many droplets of saliva were flung into the air by a person talking with and without a face mask. The paper was only recently published officially, but I saw a <a href="https://www.youtube.com/watch?v=_OSz5Gr7gG0">YouTube video</a> showing the experiment in early March. The results are shockingly obvious in the video. When the researcher used a simple cloth face cover, nearly all the droplets were blocked.</p>
<p>This evidence is only relevant if COVID-19 is transmitted by droplets from a person’s mouth. <a href="https://www.thestar.com/opinion/letters_to_the_editors/2020/05/09/evidence-shows-covid-19-is-almost-exclusively-spread-by-droplets.html">It is</a>. There are many documented super-spreading cases connected with activities – like <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6919e6.htm">singing in enclosed spaces</a> – that create a <a href="https://doi.org/10.1073/pnas.2006874117">lot of droplets</a>. </p>
<p>The light-scattering experiment cannot see “micro-droplets” that are smaller than 5 microns and could contain some viral particles. But experts don’t think that these are <a href="https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations">responsible for much COVID-19 transmission</a>. </p>
<p>While just how much of a role these small particles play in transmission remains to be seen, recent research suggests that cloth masks are also effective at reducing the spread of these smaller particles. In a paper that has not yet been peer-reviewed, researchers found that micro-droplets fell out of the air within <a href="https://arxiv.org/abs/2005.03444">1.5 meters of the person who was wearing a mask</a>, versus 5 meters for those not wearing masks. When combined with social distancing, this suggests that masks can effectively reduce transmission via micro-droplets.</p>
<p>Another recent study showed that unfitted surgical masks were <a href="https://doi.org/10.1038/s41591-020-0843-2">100% effective in blocking seasonal coronavirus</a> in droplets ejected during breathing.</p>
<p>If only people with symptoms infected others, then only people with symptoms would need to wear masks. But experts have shown that people without symptoms <a href="https://doi.org/10.1038/s41586-020-2196-x">pose a risk of infecting others</a>. In fact, <a href="https://doi.org/10.1038/s41591-020-0869-5">four</a> <a href="https://doi.org/10.5281/zenodo.3709942">recent</a> <a href="https://doi.org/10.1101/2020.03.05.20031815">studies</a> <a href="https://doi.org/10.1101/2020.04.17.20053157">show</a> that nearly half of patients are infected by people who do not themselves have symptoms.</p>
<p>This evidence seems, to me, clear and simple: COVID-19 is spread by droplets. We can see directly that a piece of cloth blocks those droplets and the virus those droplets contain. People without symptoms who don’t even know they are sick are responsible for around half of the transmission of the virus. </p>
<p>We should all wear masks.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=522&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=522&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334828/original/file-20200513-156629-1rkbpbc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=522&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Asking the wrong questions led to a misunderstanding of the medical literature around masks.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Texas/37762ea5a41245c5a36b98f1b029ccfa/12/0">AP Photo/Eric Gay</a></span>
</figcaption>
</figure>
<h2>Against the tide</h2>
<p>After going through all of this strong evidence in late March and early April, I wondered why mask-wearing was controversial amongst health organizations in the Western world. The U.S. and European CDCs did not recommend masks, and neither did nearly any western government except for Slovakia and Czechia, which both required masks in late March.</p>
<p>I think there were three key problems. </p>
<p>The first was that most researchers were looking at the wrong question – how well a mask protects the wearer from infection and not how well a mask prevents an infected person from spreading the virus. Masks function very differently as personal protective equipment (PPE) versus source control. </p>
<p>Masks are very good at blocking larger droplets and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7108646/">not nearly as good</a> at blocking tiny particles. When a person expels droplets into the air, they <a href="https://doi.org/10.1093/oxfordjournals.aje.a118097">quickly evaporate</a> and shrink to become tiny airborne particles called droplet nuclei. These are <a href="https://dx.doi.org/10.1017%2Fs0022172400019288">extremely hard to remove from the air</a>. However, in the moist atmosphere between a person’s mouth and their mask, it takes nearly <a href="https://www.wiley.com/en-us/Aerosol+Technology%3A+Properties%2C+Behavior%2C+and+Measurement+of+Airborne+Particles%2C+2nd+Edition-p-9780471194101">a hundred times as long</a> for a droplet to evaporate and shrink into a droplet nuclei.</p>
<p>This means that nearly any kind of simple cloth mask is great for source control. The mask creates humidity, this humidity prevents virus-containing droplets from turning into droplet nuclei, and this allows the fabric of the mask to block the droplets. </p>
<p>Unfortunately, nearly all of the research that was available at the start of this pandemic focused on mask efficacy as PPE. This measure is very important for protecting health care workers, but does not capture their value as source control. On Feb. 29, the U.S. <a href="https://twitter.com/surgeon_general/status/1233725785283932160">surgeon general tweeted</a> that masks “are NOT effective in preventing general public from catching #Coronavirus.” This missed the key point: They are extremely effective at preventing its spread, as our review of the literature showed.</p>
<p>The second problem was that most medical researchers are used to judging interventions on the basis of <a href="https://www.semanticscholar.org/paper/How-to-Read-a-Paper%3A-The-Basics-of-Evidence-Based-Greenhalgh/f7aa35eb0acea813682527bec5b8929b76e908ba#paper-header">randomized controlled trials</a>. These are the foundation of evidence based medicine. However, it is impossible and unethical to test mask-wearing, hand-washing or social distancing during a pandemic.</p>
<p>Experts like Trisha Greenhalgh, the author of the best-selling textbook “How to Read a Paper: The Basics of Evidence Based Healthcare,” are <a href="https://twitter.com/trishgreenhalgh/status/1257713121692712961">now asking</a>, “Is Covid-19 evidence-based medicine’s nemesis?” She and others <a href="https://doi.org/10.1136/bmj.m1435">are suggesting</a> that when a simple experiment finds evidence to support an intervention and that intervention has a limited downside, policymakers should act before a randomized trial is done. </p>
<p>The third problem is that there is a shortage of medical masks around the world. Many policymakers were concerned that recommending face coverings for the public would lead to people hoarding medical masks. This led to seemingly contradictory guidance where the CDC said there was no reason for the public to wear masks but that masks needed to be saved for medical workers. The CDC has now clarified its stance and <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html">recommends the public use of homemade masks</a> while saving higher-grade masks for medical professionals. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334819/original/file-20200513-156625-p2hmnv.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">Many countries were quick to adopt public mask-wearing while others, including the U.S., still haven’t enacted nationwide rules.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-China/14a4a3b74f56472fa05c9689adc99e85/1/0">AP Photo/Andy Wong</a></span>
</figcaption>
</figure>
<h2>Results of mask-wearing</h2>
<p>There are <a href="https://arxiv.org/abs/2004.13553">numerous</a> <a href="https://arxiv.org/abs/2003.07353">studies</a> that suggest if 80% of people wear a mask in public, then COVID-19 transmission could be halted. Until a vaccine or a cure for COVID-19 is discovered, cloth face masks might be the most important tool we currently have to fight the pandemic.</p>
<p>Given all of the laboratory and epidemiological evidence, the low cost of wearing masks – which can be made at home with no tools – and the potential to slow COVID-19 transmission with widescale use, policymakers should ensure that everyone wears a mask in public.</p>
<p>[<em>You need to understand the coronavirus pandemic, and we can help.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-help">Read The Conversation’s newsletter</a>.]</p><img src="https://counter.theconversation.com/content/138507/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeremy Howard 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>Recommendations around mask usage are confusing. The science isn’t. Evidence shows that masks are extremely effective to slow the coronavirus and may be the best tool available right now to fight it.Jeremy Howard, Distinguished Research Scientist, University of San FranciscoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1370292020-04-30T12:13:48Z2020-04-30T12:13:48ZInfected with the coronavirus but not showing symptoms? A physician answers 5 questions about asymptomatic COVID-19<figure><img src="https://images.theconversation.com/files/331570/original/file-20200429-51508-1nvhl2o.jpg?ixlib=rb-1.1.0&rect=77%2C108%2C5098%2C3321&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Even if you're feeling fine, you might be infected by the SARS-CoV-2 virus that causes COVID-19.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-wearing-protective-masks-congregate-in-times-square-news-photo/1219817150">John Lamparski/Getty Images Entertainment via Getty Images</a></span></figcaption></figure><p><em>Blood tests that check for exposure to the coronavirus are starting to come online, and preliminary findings suggest that many people have been infected without knowing it. Even people who do eventually experience the common symptoms of COVID-19 don’t start coughing and spiking fevers the moment they’re infected.</em></p>
<p><em><a href="https://scholar.google.com/citations?user=6yMIM1MAAAAJ&hl=en&oi=ao">William Petri is a professor of medicine and microbiology</a> at the University of Virginia who specializes in infectious diseases. Here, he runs through what’s known and what isn’t about asymptomatic cases of COVID-19.</em></p>
<h2>How common is it for people to contract and fight off viruses without knowing it?</h2>
<p>In general, having an infection without any symptoms is common. Perhaps the most infamous example was <a href="https://theconversation.com/typhoidmary-now-a-hashtag-was-a-maligned-immigrant-who-got-a-bum-rap-136571">Typhoid Mary</a>, who spread typhoid fever to other people without having any symptoms herself in the early 1900s.</p>
<p>My colleagues and I have found that many infections are fought off by the body without the person even knowing it. For example, when we carefully followed children for infection by the parasite <em>Cryptosporidia</em>, one of the major causes of diarrhea, <a href="https://doi.org/10.1093/cid/ciy310">almost half of those with infections showed no symptoms at all</a>.</p>
<p>In the case of the flu, estimates are that <a href="https://doi.org/10.1097/EDE.0000000000000340">anywhere from 5% to 25% of infections</a> occur with no symptoms.</p>
<p>For the most part, symptoms are actually a side effect of fighting off an infection. It takes a little time for the immune system to rally that defense, so some cases are more aptly considered <a href="http://dx.doi.org/10.15585/mmwr.mm6914e1">presymptomatic</a> rather than asymptomatic.</p>
<h2>How can someone spread coronavirus if they aren’t coughing and sneezing?</h2>
<p>Everyone is on guard against the <a href="https://theconversation.com/coronavirus-drifts-through-the-air-in-microscopic-droplets-heres-the-science-of-infectious-aerosols-136663">droplets that spray out</a> from a coronavirus patient’s cough or sneeze. They’re a big reason public health officials have suggested everyone should wear masks.</p>
<p>But the virus also spreads through <a href="https://doi.org/10.1080/02786826.2020.1749229">normal exhalations</a> that can carry tiny droplets containing the virus. A regular breath may spread the virus several feet or more.</p>
<p><a href="https://theconversation.com/viruses-live-on-doorknobs-and-phones-and-can-get-you-sick-smart-cleaning-and-good-habits-can-help-protect-you-133054">Spread could also come from fomites</a> – surfaces, such as a doorknob or a grocery cart handle, that are contaminated with the coronavirus by an infected person’s touch.</p>
<h2>What’s known about how contagious an asymptomatic person might be?</h2>
<p>No matter what, if you’ve been exposed to someone with COVID-19, you should self-quarantine for the <a href="https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html">entire 14-day incubation period</a>. Even if you feel fine, you’re still at risk of spreading the coronavirus to others.</p>
<p>Most recently it has been shown that high levels of the virus are present in respiratory secretions during the <a href="https://doi.org/10.1056/NEJMe2009758">“presymptomatic” period that can last days to more than a week</a> prior to the fever and cough characteristic of COVID-19. This ability of the virus to be transmitted by people without symptoms is a major reason for the pandemic.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/331572/original/file-20200429-51500-17uqb2h.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">To find out what percentage of people have anti-coronavirus antibodies in their blood, health departments are starting to sample the public, as at this grocery store in New York.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/april-25-2020-a-healthcare-worker-takes-a-sample-from-a-news-photo/1211025526">Xinhua News Agency via Getty Images</a></span>
</figcaption>
</figure>
<h2>After an asymptomatic infection, would someone still have antibodies against SARS-CoV-2 in their blood?</h2>
<p>Most people are developing antibodies after recovery from COVID-19, likely even those without symptoms. It is a reasonable assumption, from what scientists know about other coronaviruses, that those antibodies will offer some measure of protection from reinfection. <a href="https://www.who.int/news-room/commentaries/detail/immunity-passports-in-the-context-of-covid-19">But nothing is known for sure yet</a>. </p>
<p>Recent serosurveys in New York City that check people’s blood for antibodies against SARS-CoV-2 indicate that as many as <a href="https://www.nytimes.com/2020/04/23/nyregion/coronavirus-antibodies-test-ny.html">one in five residents</a> may have been previously infected with COVID-19. Their immune systems had fought off the coronavirus, whether they’d known they were infected or not – and many apparently didn’t.</p>
<h2>How widespread is asymptomatic COVID-19 infection?</h2>
<p>No one knows for sure, and for the moment lots of the evidence is anecdotal.</p>
<p>For a small example, <a href="https://doi.org/10.1056/NEJMoa2005412">consider the nursing home in Washington</a> where many residents became infected. Twenty-three tested positive. Ten of them were already sick. Ten more eventually developed symptoms. But three people who tested positive never came down with the illness.</p>
<p>When doctors tested 397 people staying at a homeless shelter in Boston, <a href="https://www.wbur.org/commonhealth/2020/04/14/coronavirus-boston-homeless-testing">36% came up positive for COVID-19</a> – and none of them had complained of any symptoms.</p>
<p>In the case of Japanese citizens evacuated from Wuhan, China and tested for COVID-19, fully <a href="https://www.japantimes.co.jp/news/2020/02/13/national/japan-wuhan-evacuees-go-home/#.XqjQUS2ZPOQ">30% of those infected were aymptomatic</a>.</p>
<p>An Italian pre-print study that has not yet been peer-reviewed found that <a href="https://doi.org/10.1101/2020.04.17.20053157">43% of people who tested positive for COVID-19</a> showed no symptoms. Of concern: The researchers found no difference in how potentially contagious those with and without symptoms were, based on <a href="https://theconversation.com/what-we-do-and-do-not-know-about-covid-19s-infectious-dose-and-viral-load-135991">how much of the virus the test found</a> in individuals’ samples.</p>
<p>The antibody serosurveys getting underway <a href="https://twitter.com/NYGovCuomo/status/1253352837255438338">in different</a> <a href="https://boston.cbslocal.com/2020/04/23/coronavirus-mgh-case-study-john-iafrate-herd-immunity/">parts of</a> <a href="https://www.factcheck.org/2020/04/qa-on-covid-19-antibody-tests/">the country</a> add further evidence that a good number – possibly anywhere from around 10% to 40% – of those infected might not experience symptoms.</p>
<p>Asymptomatic SARS-CoV-2 infection appears to be common – and will continue to complicate efforts to get the pandemic under control.</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><img src="https://counter.theconversation.com/content/137029/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Petri 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>Your body can be infected and fight off SARS-CoV-2 without your ever noticing.William Petri, Professor of Medicine, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1355032020-04-06T16:09:33Z2020-04-06T16:09:33ZCoronavirus FAQs: Should I wear a mask? How long will schools be closed? Can I get COVID-19 twice?<figure><img src="https://images.theconversation.com/files/325340/original/file-20200403-74235-vr65ly.jpg?ixlib=rb-1.1.0&rect=35%2C13%2C2892%2C1908&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">School's out for ... how long? An empty hallway at Eric Hamber Secondary School in Vancouver, B.C.</span> <span class="attribution"><span class="source">THE CANADIAN PRESS/Jonathan Hayward</span></span></figcaption></figure><p>The global <a href="https://coronavirus.jhu.edu/map.html">number of confirmed COVID-19 cases surpassed one million</a> in early April, nearly doubling in a week. Instead of lifting or relaxing guidelines on physical distancing, we’re seeing playgrounds cordoned off and school closures extended in an attempt to flatten the curve and lessen the load on the health-care system. </p>
<p>As people hunker down at home, questions remain about COVID-19 infection, transmission, treatment and recovery. Here are answers to some of the common questions people are asking about the coronavirus pandemic. </p>
<h2>Should I wear a mask?</h2>
<p>Currently, the accepted science is that <a href="https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks">wearing masks is best preserved for front-line health-care workers</a>. In other parts of the world, it is more common for the general public to wear masks, but evidence for their utility remains inconclusive. </p>
<p>In general, a mask protects the wearer, such as a health-care worker, from becoming infected. When someone wears a mask in public, it is usually to protect others from getting sick should they cough or sneeze. During the COVID-19 pandemic, people who are sick should be self-isolating at home and not venturing into public. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=378&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=378&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=378&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=475&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=475&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325377/original/file-20200403-74279-9h8des.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=475&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 woman paints a thank you message to nurses and doctors on a boarded up shop in downtown Vancouver, B.C., on April 1, 2020.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Jonathan Hayward</span></span>
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<p>It’s in our best interest to continue the provincial and federal efforts to preserve personal protective equipment, including masks, for the people who most need them: health-care workers and their patients.</p>
<p>Many people are crafting their own masks made from cotton at home. It may well become a new cultural norm for North Americans to wear masks. There is nothing harmful about this practice, as long as it does not become an excuse for a person who is sick to go out in public. </p>
<p>The safest and healthiest way to prevent the spread of COVID-19 remains staying home when you are sick, maintaining physical distances of at least two metres from others, not meeting in groups and cleaning your hands often.</p>
<h2>How long can you have the virus before you show symptoms?</h2>
<p><a href="https://www.who.int/news-room/q-a-detail/q-a-coronaviruses">Most estimates for this “incubation period” range from one to 14 days</a>, with five days being common. </p>
<p>People who are infected with the coronavirus are thought to be the most infectious when they are showing the most symptoms. But infection and transmission can sometimes occur when a person has the virus but doesn’t have any symptoms (they are asymptomatic).</p>
<p>These people can unknowingly spread the coronavirus to other people because they don’t realize they are infected. This is why it is important to stay home and keep up with social distancing — limiting the number of people you come into close contact with. It works, and it can help protect vulnerable people in our communities. </p>
<h2>Is there a test to tell me if I’ve already had COVID-19?</h2>
<p>When someone is infected with a virus, their immune system begins producing antibodies to that virus. A test that looks for coronavirus-specific antibodies could determine if someone has already had COVID-19, and it could help scientists understand how widespread the disease is.</p>
<p>The U.S. Food and Drug Administration <a href="https://www.fda.gov/emergency-preparedness-and-response/counterterrorism-and-emerging-threats/coronavirus-disease-2019-covid-19">authorized the first antibody test for COVID-19 on April 1</a>. We don’t have this test in Canada yet. </p>
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Read more:
<a href="https://theconversation.com/coronavirus-faqs-can-people-without-symptoms-spread-covid-19-how-long-does-it-live-on-surfaces-what-cleaning-products-kill-the-virus-134945">Coronavirus FAQs: Can people without symptoms spread COVID-19? How long does it live on surfaces? What cleaning products kill the virus?</a>
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<p>Many academic laboratories and medical companies around the world are working to produce these blood tests. They would be able to quickly identify antibodies in people who have already been infected with the virus, but experienced no symptoms or only very mild ones. </p>
<h2>Can someone who has recovered from the virus still be a host?</h2>
<p>This remains unclear. There are a small number of people who have been diagnosed with COVID-19, stopped showing symptoms, had two consecutive negative test results two days apart and been discharged from the hospital, but have <a href="https://doi.org/10.1016/j.ijid.2020.03.003">subsequently tested positive for the infection again</a>.</p>
<p>This suggests that <a href="https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.10.2000191">some patients who have recovered may still be contagious</a>, but this must still be confirmed.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325821/original/file-20200406-51213-fy19wm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&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 man wearing a mask walks along a near-deserted street in Old Montréal on March 31, 2020.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Paul Chiasson</span></span>
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<p>Generally, the “viral load” — a measure of how much virus the body is carrying — gradually decreases over time after symptoms have resolved. But in some cases, the <a href="https://www.publichealthontario.ca/-/media/documents/ncov/covid-wwksf/what-we-know-communicable-period-mar-27-2020.pdf?la=en">virus’s genetic material (RNA) can be detected in people</a> for three weeks or more since their symptoms first appeared. </p>
<p>The levels of viral RNA detected in these studies were low and likely represented remnants of viral RNA, not live virus. But we still don’t have enough evidence yet to confirm this. </p>
<h2>Can you get COVID-19 more than once?</h2>
<p>Even mild cases should leave recovered patients with some immunity against the virus. But some patients have reported being infected a second time and showing symptoms again. </p>
<p>In one study of 55 patients in China, <a href="https://doi.org/10.1016/j.jinf.2020.03.001">reactivation occurred in nine per cent of them</a>. The clinical characteristics of these patients were no different from first-time COVID-19 patients. The study didn’t identify any reliable markers that would allow doctors to predict the reactivation risk of the SARS-CoV-2 coronavirus.</p>
<h2>Can COVID-19 survivors’ blood help others recover?</h2>
<p>When people recover from an illness, their blood plasma remains rich with the antibodies that helped fight off that disease. This “convalescent plasma” has been used as a treatment, called passive antigenic therapy, for other people who become ill with the same disease. </p>
<p>This approach was used as an emergency measure during the SARS outbreak in 2003 and for people with Ebola in 1995, but it is not used as a standard treatment. </p>
<p>At this time, the use of convalescent plasma to treat critically ill adults with COVID-19 <a href="https://www.sccm.org/getattachment/Disaster/SSC-COVID19-Critical-Care-Guidelines.pdf?lang=en-US">is not recommended</a>, largely because there aren’t enough data yet to show that it is safe and that it works. These recommendations could change with more data and studies. </p>
<h2>How long might school and business closures last?</h2>
<p>“Flatten the curve” has become a global rallying cry. Epidemiologists are working extremely hard to model various scenarios for our governments to predict the course of the disease. This could tell us if — and when — we can relax the restrictions and other strategies implemented in March. </p>
<p>In Canada, the number of cases we see in the first weeks of April, and the severity of these cases, will give us an indication of the impact travel restrictions and social distancing measures have made. With concrete numbers in hand, epidemiologists can adjust and refine models to better understand how long our schools and businesses will remain closed.</p>
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<img alt="" src="https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&rect=59%2C21%2C3519%2C2662&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325129/original/file-20200402-74878-tnnnma.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&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">People exercise near Lake Ontario in Toronto on April 2, 2020.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Nathan Denette</span></span>
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<p>A <a href="https://www.cbc.ca/news/canada/toronto/covid-19-ontario-hospital-intensive-care-patients-suspected-1.5514041">recent report predicts the demand for ICU beds for patients with COVID-19 may peak in early to mid-April</a> in Ontario. This means we should keep up with physical distancing — and strict isolation for all those confirmed or suspected of having COVID-19 — for at least another few weeks. This is why Ontario extended its emergency declaration and schools remain closed until May 4. </p>
<p>We know these emergency health measures have social and economic impacts on our communities. Tedros Adhanom Ghebreyesus, the director-general of the World Health Organization, offered some encouraging remarks as he closed the March 30 media briefing: </p>
<p>“With solidarity, humility and assuming the best of each other, we can — and will — overcome this together.”</p>
<p><em>Suzanne Biro from Kingston, Frontenac and Lennox & Addington Public Health co-authored this story.</em></p>
<p><em>Have questions about COVID-19? Let us find an expert to answer them. <a href="https://theconversation.com/ca/pitches/readers/new">Send us your questions and story ideas</a>.</em></p>
<p><em>Editor’s note: This article was based on information available at the time of publication. The COVID-19 situation is changing rapidly, and as new information becomes available, public health officials may change their recommendations. Please see our <a href="https://theconversation.com/ca/covid-19">ongoing coverage of COVID-19</a> for the most up-to-date information.</em></p><img src="https://counter.theconversation.com/content/135503/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kieran Moore works for Kingston, Frontenac and Lennox & Addington Public Health.</span></em></p>Questions remain about COVID-19 infection, transmission, treatment and recovery. Here are answers to some common questions about the coronavirus pandemic.Kieran Moore, Professor, Departments of Emergency and Family Medicine, Queen's University, OntarioLicensed as Creative Commons – attribution, no derivatives.