tag:theconversation.com,2011:/fr/topics/sabin-vaccine-75788/articlesSabin vaccine – The Conversation2022-09-21T12:35:27Ztag:theconversation.com,2011:article/1899342022-09-21T12:35:27Z2022-09-21T12:35:27ZPolio vaccination rates in some areas of the US hover dangerously close to the threshold required for herd immunity – here’s why that matters<figure><img src="https://images.theconversation.com/files/484423/original/file-20220913-3906-gl2l50.jpg?ixlib=rb-1.1.0&rect=0%2C18%2C4102%2C2990&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In 1956, during the height of the polio epidemic in the U.S., health officials in Chicago offer polio shots at a public school.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/free-chicago-illinois-mrs-rose-stamler-uses-microphone-to-news-photo/514975204?adppopup=true">Bettmann via Getty Images</a></span></figcaption></figure><p>Given recent headlines, you may be wondering why polio is even an issue in 2022. For more than 60 years, vaccines against the poliovirus <a href="https://www.cdc.gov/vaccines/pubs/pinkbook/polio.html#">have protected virtually everyone</a> in the United States from the disease. Due to an enormously successful polio vaccination campaign beginning in the 1950s when the <a href="https://www.who.int/news-room/spotlight/history-of-vaccination/history-of-polio-vaccination">first polio vaccines became available</a>, by 1979 polio was <a href="https://www.cdc.gov/polio/why-are-we-involved/index.htm#">considered eliminated in the U.S.</a> </p>
<p>Unfortunately, even today, there are communities in the U.S. that have lower-than-necessary polio vaccination rates. Because many people have not been vaccinated, there is now a real <a href="https://theconversation.com/fears-of-a-polio-resurgence-in-the-us-have-health-officials-on-high-alert-a-virologist-explains-the-history-of-this-dreaded-disease-189107">possibility of a resurgence of polio in the U.S</a>. </p>
<p>As a <a href="https://scholar.google.com/citations?user=G2EkJJ0AAAAJ&hl=en">clinical professor of pharmacy</a>, I train future pharmacists about how vaccines work, their importance and how they prevent diseases. </p>
<p>Public health experts’ longstanding concerns over falling vaccination rates rose to the surface when, in July 2022, a man from Rockland County, New York, <a href="https://www.cdc.gov/mmwr/volumes/71/wr/mm7133e2.htm">was diagnosed with polio</a>, the first such diagnosis in the U.S. <a href="https://www.nytimes.com/2022/07/21/nyregion/polio-case-new-york.html">in nearly a decade</a>. The patient – who developed the severe, paralytic form of the disease – had been exposed to an <a href="https://theconversation.com/polio-in-new-york-an-infectious-disease-doctor-explains-this-exceedingly-rare-occurrence-187518">altered live vaccine strain from overseas</a>.</p>
<p>Then on Sept. 9, 2022, New York declared a <a href="https://www.governor.ny.gov/executive-order/no-21-declaring-disaster-state-new-york">state of emergency</a> due to ongoing poliovirus transmission. As of that date, using wastewater surveillance, officials had identified <a href="https://health.ny.gov/diseases/communicable/polio/wastewater.htm">57 samples of poliovirus in wastewater</a> from four New York counties. More than half of those were detected in the same county where the adult patient is from, just outside New York City.</p>
<p>As a result of the continued poliovirus detection in wastewater, the Centers for Disease Control and Prevention declared that the U.S. now meets the World Health Organization’s criteria for “a <a href="https://www.cdc.gov/media/releases/2022/s0913-polio.html">country with circulating vaccine-derived poliovirus</a>.”</p>
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<figcaption><span class="caption">The U.S. has recorded its first case of polio in the U.S. in nearly a decade.</span></figcaption>
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<h2>Two main poliovirus vaccine types</h2>
<p>There are two key types of polio vaccine <a href="https://www.cdc.gov/cpr/polioviruscontainment/diseaseandvirus.htm">in use around the world today</a>. The <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/ipv/">inactivated poliovirus vaccine</a> is given as a shot, and the <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/opv/">oral attenuated (or weakened) poliovirus vaccine</a> is administered as oral drops, sometimes on a sugar cube.</p>
<p>Since 2000, the U.S. has exclusively used the inactivated poliovirus vaccine, which cannot cause disease since it does not contain live virus. But in countries where the poliovirus continues to circulate, <a href="https://polioeradication.org/where-we-work/polio-endemic-countries/">such as Pakistan and Afghanistan</a>, the <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/opv/">oral attenuated poliovirus vaccine</a> is still used. </p>
<p>In <a href="https://polioeradication.org/wp-content/uploads/2016/09/Position-statement_OPVsafety.pdf">extremely rare cases</a>, the weakened live vaccine used in other countries can mutate back into its virulent form and lead to paralysis. This is how the adult in New York is believed to have come into contact with the virus.</p>
<h2>How ‘herd immunity’ for polio is determined</h2>
<p>The degree to which a community is protected from a pathogen like poliovirus comes down to <a href="https://doi.org/10.1001/jama.2020.20895">herd immunity</a>. When a community – the so-called herd – reaches a threshold of immunity, it can prevent the transmission of a pathogen from person to person, thereby quelling the pathogen. </p>
<p>The herd immunity threshold for a given disease is calculated based upon the expected number of individuals who an infected person would spread it to if they were susceptible. The higher the number of individuals who would become infected, the higher the percentage of the community or population that <a href="https://doi.org/10.1093/cid/cir007">needs to be vaccinated</a> to avoid continued spread of the disease. </p>
<p>For poliovirus, researchers estimate that between five and seven individuals would be infected for each case <a href="https://doi.org/10.4161/hv.18444">if those people were susceptible</a>. Based upon these calculations, experts determined that at least 80% of a community or population should be vaccinated against poliovirus to prevent its spread. </p>
<h2>Falling vaccination rates</h2>
<p>Throughout the U.S., vaccination rates for polio vary significantly. </p>
<p>The CDC recommends that infants and young children receive a <a href="https://www.cdc.gov/vaccines/vpd/polio/public/index.html#">four-dose schedule of the inactivated poliovirus vaccine</a> at 2 months, 4 months, 6 to 18 months and 4 to 6 years. For those who begin vaccination later – as older children, teens or adults – three doses is considered to be complete vaccination. This is because three doses of inactivated poliovirus vaccination have been shown to provide <a href="https://www.cdc.gov/vaccines/vpd/polio/hcp/effectiveness-duration-protection.html#">between 99% and 100% protection against severe disease</a>. </p>
<p>Although all U.S. states are currently above the 80% herd immunity threshold for poliovirus, there are areas within the country that include many pockets of unvaccinated or undervaccinated individuals – those who have not received a total of three lifetime doses of the inactivated vaccine.</p>
<p>New York state, for example, holds one of the highest kindergarten polio vaccination rates in the country, <a href="https://www.cdc.gov/vaccines/imz-managers/coverage/schoolvaxview/data-reports/index.html">with 97.9%</a> of kindergartners vaccinated in the 2020-2021 school year. But current estimates by the New York State Department of Public Health suggest that only <a href="https://health.ny.gov/diseases/communicable/polio/county_vaccination_rates.htm">79% of 2-year-olds in that state</a> have received three doses of the polio vaccine. </p>
<p>Further, in certain pockets and counties of New York, such as Rockland, Orange and Sullivan, three-dose vaccination rates may be far lower based on the 2-year-old age group, which is the only data that is available by county: Rockland 60%, Orange 59% and Sullivan 62%. In fact, 46% of counties in New York are below the three-dose poliovirus vaccination <a href="https://health.ny.gov/diseases/communicable/polio/county_vaccination_rates.htm">herd immunity threshold for 2-years-olds</a>. </p>
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<figcaption><span class="caption">Most people today don’t remember the polio outbreak that terrorized Americans during the first half of the 20th century.</span></figcaption>
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<h2>Vaccine recommendations</h2>
<p>When children fall more than one month behind on recommended polio vaccination, doctors recommend routine catch-up throughout adolescence. </p>
<p>Because most adults in the U.S. today were vaccinated as children and the <a href="https://www.cdc.gov/polio/why-are-we-involved/index.htm#">U.S. had eliminated polio as of 1979</a>, there was little reason for health experts to believe an adult would come into contact with poliovirus in the U.S. For that reason, catch-up vaccination for adults has not been included on the routine adult vaccination schedule. </p>
<p>But in August 2022, the CDC updated its guidance. In light of the fact that there are communities where poliovirus vaccination rates have fallen below the 80% threshold needed for herd immunity, coupled with the ongoing circulation of poliovirus in New York, the CDC now recommends that all unvaccinated or undervaccinated adults in these communities <a href="https://www.cdc.gov/vaccines/vpd/polio/public/index.html#">receive a poliovirus vaccination</a>. </p>
<p>Additionally, the CDC suggests that some fully vaccinated adults who are at increased risk of exposure may benefit from a single lifetime poliovirus booster dose. This includes health care providers who care for those with poliovirus, or people traveling to areas where poliovirus has not been eliminated.</p>
<p>If you are unsure if you need vaccination or what steps you should take, talk to your pharmacist or primary care physician.</p><img src="https://counter.theconversation.com/content/189934/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Girotto consults for Lexi-Comp. She has received grant funds from Pfizer to support independent quality improvement specific to outpatient antimicrobial stewardship. </span></em></p>With poliovirus circulating in New York, health authorities worry that pockets of the county with low polio vaccination rates could give the virus a foothold.Jennifer Girotto, Clinical Professor of Pharmacy Practice, University of ConnecticutLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1875182022-07-22T21:53:50Z2022-07-22T21:53:50ZPolio in New York – an infectious disease doctor explains this exceedingly rare occurrence<figure><img src="https://images.theconversation.com/files/475697/original/file-20220722-18-x3p6wo.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C1794%2C1196&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Polio is endemic only in Afghanistan and Pakistan in 2022.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/Polio/221757d74c22419095b557a6d3e4ab75/photo?Query=polio&mediaType=photo&sortBy=arrivaldatetime:desc&dateRange=Anytime&totalCount=1705&currentItemNo=2">Sarah Poser, Meredith Boyter Newlove/CDC via AP</a></span></figcaption></figure><p><em>The first case of polio in the U.S. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779436/">since 2013</a> was announced by New York state <a href="https://health.ny.gov/press/releases/2022/2022-07-21_polio_rockland_county.htm">health officials on July 21, 2022</a>. The U.S. resident had not been vaccinated.</em></p>
<p><em>Polio was a common cause of paralysis in children before <a href="https://theconversation.com/lessons-from-how-the-polio-vaccine-went-from-the-lab-to-the-public-that-americans-can-learn-from-today-145604">safe and effective vaccines were invented</a> in the mid-20th century. Thanks to global vaccination campaigns, polio is now almost eradicated, with <a href="https://polioeradication.org/polio-today/polio-now/this-week/">only 13 cases of endemic wild poliovirus reported</a> in 2022 to date worldwide.</em></p>
<p><em>The New York patient reportedly contracted a form of polio that can be traced back to the live, but weakened, poliovirus used in the <a href="https://www.cdc.gov/vaccines/vpd/polio/public/index.html">oral polio vaccine</a>. This version of the vaccine has <a href="https://www.cdc.gov/media/pressrel/r990617.htm">not been used in the U.S. since 2000</a>. Health officials said the virus affecting the male patient, who has muscle weakness and paralysis, <a href="https://health.ny.gov/press/releases/2022/2022-07-21_polio_rockland_county.htm">likely originated somewhere overseas</a>, where oral vaccines are still administered.</em></p>
<p><em><a href="https://scholar.google.com/citations?user=6yMIM1MAAAAJ&hl=en&oi=ao">William Petri</a> is an infectious disease specialist and chair of the World Health Organization’s <a href="https://polioeradication.org/tools-and-library/current-research-areas/polio-research-committee/">Polio Research Committee</a>. Here he explains what <a href="https://www.cdc.gov/vaccines/vpd/polio/hcp/vaccine-derived-poliovirus-faq.html">vaccine-derived poliovirus</a> is and why the inactivated polio vaccine administered in the U.S. today can’t cause it.</em></p>
<h2>What are the two kinds of polio vaccine?</h2>
<p>Vaccines introduce a harmless version of a pathogen to your body. The idea is that <a href="https://www.cdc.gov/vaccines/hcp/conversations/understanding-vacc-work.html">they train your immune system</a> to fight off the real germ if you ever encounter it.</p>
<p>The oral polio vaccine, <a href="https://doi.org/10.1126/science.288.5471.1593">originally developed by Albert Sabin</a>, uses a live but weakened poliovirus that one swallows in a sugar cube or droplet. Scientists weaken – or attenuate – the virus so it can no longer cause disease. </p>
<p>The other kind of polio vaccine was <a href="https://doi.org/10.1126/science.288.5471.1593">originally developed by Jonas Salk</a>. It contains inactivated, dead virus. It is administered by an injection.</p>
<p>In the U.S., children receive the inactivated polio vaccine <a href="https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html">at 2, 4 and 6 months of age</a>. It provides nearly complete protection from paralytic polio.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="adult hands administer a drop of medicine to a boy with open mouth" src="https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/475699/original/file-20220722-12-3gho47.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>
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<span class="caption">A boy in Pakistan receives a dose of the oral polio vaccine.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/PakistanPolio/23a6599533e34577b64f4932393fa80a/photo?Query=polio&mediaType=photo&sortBy=arrivaldatetime:desc&dateRange=Anytime&totalCount=1705&currentItemNo=17">AP Photo/Muhammad Sajjad</a></span>
</figcaption>
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<h2>How can the live vaccine lead to a case of polio?</h2>
<p>The weakened form of the live virus in the oral vaccine cannot cause disease. However, because the vaccine is given orally, the weakened virus is excreted in the feces and can <a href="https://www.who.int/news-room/questions-and-answers/item/poliomyelitis-vaccine-derived-polio">spread from someone who is vaccinated to their close contacts</a>. If the weakened virus circulates person to person for long enough, it can mutate and regain its ability to cause paralysis.</p>
<p>The <a href="https://www.who.int/news-room/questions-and-answers/item/poliomyelitis-vaccine-derived-polio">mutated virus can then infect people</a> in communities with poor sanitation and low vaccination rates, causing disease and even paralysis. </p>
<p>This is an exceedingly rare occurrence. With more than 10 billion doses of the oral polio vaccine administered since 2000, there have been <a href="https://polioeradication.org/polio-today/polio-now/this-week/circulating-vaccine-derived-poliovirus/">fewer than 800 cases of vaccine-derived polio</a> reported.</p>
<p>Apparently, the current patient in New York was somehow exposed to a mutated poliovirus that had been transmitted after vaccination overseas. Earlier this summer, routine surveillance spotted <a href="https://www.who.int/news/item/22-06-2022-vaccine-derived-poliovirus-type-2-(vdpv2)-detected-in-environmental-samples-in-london--uk">vaccine-derived poliovirus in London’s sewage system</a>, but no cases have been reported there. </p>
<h2>Why use the oral vaccine anywhere if it comes with this risk?</h2>
<p>There’s a positive aspect to the fact that the weakened live virus can circulate in the community once oral vaccine recipients shed it in their feces. Traveling a feces-to-oral route, it can <a href="https://polioeradication.org/polio-today/polio-prevention/the-vaccines/opv/">help induce immunity</a> even in people who weren’t directly vaccinated. The oral polio vaccine is also <a href="https://doi.org/10.1093/infdis/jiu128">cheaper and easier to administer</a> than inactivated polio vaccines.</p>
<p>Most importantly, the live-virus vaccine stops transmission of wild poliovirus in a way that the inactivated-virus vaccine does not. The <a href="https://doi.org/10.1126/science.abb8588">eradication of polio</a> in the Americas, Europe and Africa has been accomplished solely through the use of the live oral vaccine. Once polio has been wiped from a continent, then it is safe to stop using the oral live vaccine and use only the inactivated vaccine, <a href="https://www.cdc.gov/cpr/polioviruscontainment/diseaseandvirus.htm">which does prevent disease in recipients</a> and does not pose the rare risk of vaccine-derived paralytic polio.</p>
<p><a href="https://polioeradication.org/nopv2/">A new and safer oral polio vaccine</a> that has been engineered not to mutate is now <a href="https://doi.org/10.1126/science.abb8588">replacing the earlier live-virus vaccine</a>. Thus, even this extremely rare complication of polio vaccination should soon become a thing of the past.</p>
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<figcaption><span class="caption">WHO: Polio Eradication – Reaching Every Last Child.</span></figcaption>
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<h2>How close is the world to eradicating polio?</h2>
<p>Thanks to <a href="https://polioeradication.org">tremendous global effort</a>, two of the three viruses that cause polio have been eradicated. The world is now on the verge of eradicating the final one, wild poliovirus 1 (WPV1).</p>
<p><a href="https://polioeradication.org/polio-today/polio-now/this-week/">Today endemic polio is found</a> only in Pakistan, with 12 cases of paralytic polio so far in 2022, and Afghanistan, with just one case this year. Africa has two cases, imported from overseas, which are being contained by additional vaccination campaigns.</p>
<p>Once wild poliovirus has been eradicated from the planet, vaccination efforts may be able to switch to the inactivated polio vaccine, eliminating the risk of any future vaccine-derived cases.</p><img src="https://counter.theconversation.com/content/187518/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Petri receives research funding from the NIH and the Gates Foundation.</span></em></p>The oral polio vaccine – which is no longer given in the US – relies on a live but weakened virus that can actually be passed from person to person.William Petri, Professor of Medicine, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1528062021-01-14T13:21:16Z2021-01-14T13:21:16ZThe great polio vaccine mess and the lessons it holds about federal coordination for today’s COVID-19 vaccination effort<figure><img src="https://images.theconversation.com/files/378566/original/file-20210113-23-12pkx5x.jpg?ixlib=rb-1.1.0&rect=0%2C299%2C4991%2C3539&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Elementary students initially received polio vaccines at school.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/view-of-a-classroom-as-children-receive-polio-vaccinations-news-photo/618896932">PhotoQuest/Archive Photos via Getty Images</a></span></figcaption></figure><p>I nervously fell into a long line of fellow first graders in the gymnasium of St. Louis’ Hamilton Elementary School in the spring of 1955. We were waiting for our first injection of the new polio vaccine.</p>
<p>The National Foundation for Infantile Paralysis – with money raised through its annual March of Dimes campaign – had sponsored field tests for a vaccine developed by Jonas Salk. The nonprofit had acquired sufficient doses to inoculate all the nation’s first and second graders through simultaneous rollouts administered at their elementary schools. The goal was to give 30 million shots <a href="https://www.marchofdimes.org/mission/a-history-of-the-march-of-dimes.aspx">over three months</a>.</p>
<p>Now, more than six decades later, attention focuses on the rollout of two COVID-19 vaccines, following their <a href="https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/pfizer-biontech-covid-19-vaccine">emergency use authorization</a> by the U.S. Food and Drug Administration. States have begun to administer them in a <a href="https://www.npr.org/2021/01/03/952969795/what-the-u-s-can-do-about-vaccine-rollout-issues">rocky and frustratingly slow delivery process</a> – while <a href="https://www.statista.com/statistics/1102816/coronavirus-covid19-cases-number-us-americans-by-day/">hundreds of thousands of new cases</a> continue to be diagnosed daily in the U.S.</p>
<p>While not necessarily comforting, it is useful to recognize that the early days and weeks of mass distribution of a new medication, particularly one that is intended to address a fearful epidemic, are bound to be frustrating. Only after examining the complex polio vaccine distribution process as documented in papers collected in the <a href="https://www.eisenhowerlibrary.gov/">Dwight D. Eisenhower Presidential Library</a> did I come to understand how partial my childhood memories actually were.</p>
<h2>Vaccine distribution, 65 years ago</h2>
<p>After I received my polio shot, I remember my parents’ relief.</p>
<p>The polio virus causes flu-like symptoms in most people who catch it. But in a minority of those infected, the brain and spinal cord are affected; polio can cause paralysis and even death. With the distribution of Salk’s vaccine, the <a href="https://global.oup.com/academic/product/polio-9780195152944">much-feared stalker of children and young adults</a> had seemingly been tamed. Within days, however, the initial mass inoculation program <a href="https://www.jstor.org/stable/4638326">went off the rails</a>.</p>
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<a href="https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Jonas Salk poses with a flask in lab" src="https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=789&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=789&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=789&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=992&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=992&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378571/original/file-20210113-23-6mt7t0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=992&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The world initially rejoiced as Salk’s vaccine came online. He declined to patent it, to make it available to all.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/view-of-american-scientist-and-physician-jonas-salk-news-photo/109274461">PhotoQues/Archive Photos via Getty Images</a></span>
</figcaption>
</figure>
<p>Immediately following the government’s licensing of the Salk vaccine, the National Foundation for Infantile Paralysis contracted with private drug companies for US$9 million worth of vaccine (around $87 million today) – about 90% of the stock. They planned to provide it free to the <a href="https://www.google.com/books/edition/Patenting_the_Sun/qIHhAAAAMAAJ?hl=en">country’s first and second graders</a>. But just two weeks after the first doses were administered, the Public Health Service reported that six inoculated children had come down with polio.</p>
<p>As the number of such incidents grew, it became clear that some of the shots were causing the disease they were meant to prevent. A <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1383764/">single lab</a> had inadvertently released adulterated doses.</p>
<p>After considerable fumbling and outright denial, Surgeon General Leonard Steele first pulled all tainted vaccine off the market. Then, less than a month after the initial inoculations, the U.S. <a href="https://oac.cdlib.org/findaid/ark:/13030/kt3c6031cw/entire_text/">shut down distribution entirely</a>. It wasn’t until the introduction of a <a href="https://www.statnews.com/2018/03/01/albert-sabin-polio-vaccine/">new polio vaccine</a> in 1960, created by Albert Sabin, that public trust returned.</p>
<h2>History’s lessons for 2021</h2>
<p>This story offers several lessons relevant to the COVID-19 vaccine distribution just now getting rolling.</p>
<p>First, federal coordination of an emergent lifesaving medical product is critical.</p>
<p>The federal government had declined to play an active oversight and coordination role for the polio vaccine, but still wanted the credit. The federal Department of Health, Education and Welfare (now Health and Human Services) offered no plan for distribution beyond the privately funded school-based program.</p>
<p>The department waited a full month after the vaccine was first administered before bringing together a permanent scientific clearance panel. That delay had less to do with formal procedures than with the ideological opposition of Health, Education and Welfare Secretary <a href="https://www.womenshistory.org/education-resources/biographies/oveta-hobby">Oveta Culp Hobby</a>.</p>
<p>Hobby was a political appointee who had taken office <a href="https://www.tshaonline.org/handbook/entries/hobby-oveta-culp">just months before the vaccine was approved</a>. Her reluctance to involve the federal government in matters that she believed were best left in private hands – and her oft-stated fear of “<a href="https://www.nytimes.com/1955/06/15/archives/mrs-hobby-terms-free-vaccine-idea-a-socialistic-step-charges.html">socialized medicine</a>” – meant that safety checks would be left to the private labs producing the vaccine. The results immediately caused dire problems and even avoidable deaths.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People protesting pandemic restrictions and rules, one holds a 'No vaccines' sign" src="https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378573/original/file-20210113-23-steevs.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 May 2020, Trump supporters in California protested against a COVID-19 vaccine months before one was even available.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/protester-holds-an-anti-vaccination-sign-as-supporters-of-news-photo/1213388386">David McNew/Getty Images News via Getty Images</a></span>
</figcaption>
</figure>
<p>Second, the polio vaccine distribution process demonstrated how vital it is for the federal government to act in ways deserving of public trust.</p>
<p>In those hopeful first few weeks of the polio vaccine distribution, those of us lining up for shots had little to fear beyond the sting of an injection. That changed quickly.</p>
<p>Once some children had in fact been harmed by the shot, obfuscation by government officials, clumsy explanations and delayed responses engulfed the entire production and distribution process in confusion and suspicion. Trust in the government and the vaccine eroded accordingly. Gallup polls found that by June 1955, almost half of the parents who responded said they <a href="http://www.ibiblio.org/pha/Gallup/Gallup.pdf">would not take any further vaccine shots</a> – and the full regimen of polio inoculation required three doses. In 1958, some drug companies halted production, citing “<a href="https://www.jstor.org/stable/4638326">public apathy</a>.” It wasn’t surprising to see a startling <a href="http://www.ibiblio.org/pha/Gallup/Gallup.pdf">upsurge in polio in 1959</a>, doubling cases from the previous year. </p>
<p>Today, with COVID-19 already highly politicized – polls suggest that a <a href="https://www.kff.org/coronavirus-covid-19/report/kff-covid-19-vaccine-monitor-december-2020/">minority of Americans will decline to take any vaccine</a> – it is critical to administer an effective vaccine delivery program in a manner that builds trust rather than undermines it.</p>
<p>Scattered reports of allergic reactions to the COVID-19 vaccine have generated not the denials of the Eisenhower administration but rather honest and realistic responses from the <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/allergic-reaction.html">Centers for Disease Control and Prevention</a>. Particularly for vaccines that require multiple inoculations – both Pfizer and Moderna vaccines require <a href="https://www.statnews.com/2020/12/19/a-side-by-side-comparison-of-the-pfizer-biontech-and-moderna-vaccines/">two shots administered with a 21- or 28-day gap</a> – mass inoculations will require not just an initial willingness to get the first dose but the maintenance of trust sufficient to get people back for the followup. </p>
<p>There are significant differences in the social-political contexts of the era in which the polio vaccine was distributed and today, including the nature and threat of the two diseases and the technologies of the vaccines. But time and again, the COVID-19 pandemic has revealed disconcerting parallels with mistakes made in the past. The good news is vaccination works – no case of polio has originated <a href="https://www.cdc.gov/polio/what-is-polio/polio-us.html">in the U.S. since 1979</a>. </p>
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<p class="fine-print"><em><span>Bert Spector 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>Massive vaccine distribution efforts take a lot of coordination. The rollout of the Salk polio vaccine in the US in 1955 holds lessons for those delivering COVID-19 shots today.Bert Spector, Associate Professor of International Business and Strategy at the D'Amore-McKim School of Business, Northeastern UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1339762020-03-25T12:27:30Z2020-03-25T12:27:30ZThe deadly polio epidemic and why it matters for coronavirus<figure><img src="https://images.theconversation.com/files/321088/original/file-20200317-60901-1gzviny.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C3000%2C2335&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An emergency polio ward in Boston in 1955 equipped with iron lungs. These pressurized respirators acted as breathing muscles for polio victims, often children, who were paralyzed.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Associated-Press-Domestic-News-Massachusetts-Un-/ade0290b02e5da11af9f0014c2589dfb/15/0">www.apimages.com</a></span></figcaption></figure><p>The fear and uncertainty surrounding the coronavirus pandemic may feel new to many of us. But it is strangely familiar to those who lived through the polio epidemic of the last century. </p>
<p>Like a horror movie, throughout the first half of the 20th century, the polio virus arrived <a href="https://www.cdc.gov/polio/what-is-polio/polio-us.html">each summer, striking without warning</a>. No one knew how polio was transmitted or what caused it. There were wild theories that the virus spread from <a href="https://books.google.com/books?id=JumHQwdeAd0C&pg=PA10&lpg=PA10&dq=Paul+offit+cats+bananas+caused+polio&source=bl&ots=xe3GuWPgiK&sig=ACfU3U0IMY6kBzq4ObB4dFGfYXonwvS5SA&hl=en&sa=X&ved=2ahUKEwjaj5T7xrHoAhVfgnIEHRtjD2MQ6AEwAnoECAoQAQ#v=onepage&q=Paul%20offit%20cats%20bananas%20caused%20polio&f=false">imported bananas or stray cats</a>. There was no known cure or vaccine. </p>
<p>For the next four decades, <a href="https://books.google.com/books?id=p4YRDAAAQBAJ&pg=PA72&lpg=PA72&dq=polio+oshinsky+swimming+pools+closed+each+summer+playgrounds&source=bl&ots=XQDhmCcXjf&sig=ACfU3U1JWg5hO33KcCWBwUzeXtpT_O01Mg&hl=en&sa=X&ved=2ahUKEwjUkdT43bHoAhUfl3IEHRq7AI0Q6AEwCXoECAwQAQ#v=onepage&q=polio%20oshinsky%20swimming%20pools%20closed%20each%20summer%20playgrounds&f=false">swimming pools and movie theaters closed during polio season</a>
for fear of this invisible enemy. Parents stopped sending their children to playgrounds or birthday parties for fear they would “catch polio.” </p>
<p>In the outbreak of 1916, health workers in New York City would physically remove children from their homes or playgrounds if they suspected they might be infected. Kids, who seemed to be targeted by the disease, were taken from their families and isolated in sanitariums. </p>
<p>In 1952, the number of polio cases in the U.S. <a href="https://ourworldindata.org/polio">peaked at 57,879</a>, resulting in 3,145 deaths. Those who survived this highly infectious disease could end up with some form of paralysis, forcing them to use crutches, wheelchairs or to be put into <a href="https://amhistory.si.edu/polio/howpolio/ironlung.htm">an iron lung</a>, a large tank respirator that would pull air in and out of the lungs, allowing them to breathe. </p>
<p>Ultimately, poliomyelitis was conquered in 1955 by a vaccine developed by Jonas Salk and his team at the University of Pittsburgh.</p>
<p>In conjunction with the 50th anniversary celebration of the polio vaccine, I produced a documentary, “<a href="https://www.steeltown.org/poliofilm/">The Shot Felt ‘Round the World,</a>” that told the stories of the many people who worked alongside Salk in the lab and participated in vaccine trials. As a filmmaker and <a href="https://www.filmandmedia.pitt.edu/people/carl-kurlander">senior lecturer</a> at the University of Pittsburgh, I believe these stories provide hope in the fight to combat another unseen enemy, coronavirus. </p>
<h2>Pulling together as a nation</h2>
<p>Before a vaccine was available, polio caused more than <a href="https://www.cdc.gov/polio/what-is-polio/polio-us.html">15,000 cases of paralysis a year</a> in the U.S. It was the <a href="http://www.nbcnews.com/id/56324818/ns/technology_and_science-science/t/polio-vaccine-how-us-most-feared-disease-was-eradicated/#.XnkqpNNKiL8">most feared disease of the 20th century</a>. With the success of the polio vaccine, Jonas Salk, 39, became one of the most celebrated scientists in the world. </p>
<p>He refused a patent for his work, saying the vaccine belonged to the people and that to patent it would be like “patenting the Sun.” Leading drug manufacturers made the vaccine available, and <a href="https://doi.org/10.1377/hlthaff.24.3.622">more than 400 million doses</a> were distributed between 1955 and 1962, reducing the cases of polio by 90%. By the end of the century, the polio scare had become a faint memory.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/322390/original/file-20200323-112700-1lp52jt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">First and second graders in San Diego line up to be vaccinated in 1955.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/san-diego-california-first-and-second-graders-at-the-kit-news-photo/514704620?adppopup=true">Bettman Collection via Getty Images</a></span>
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</figure>
<p>Developing the vaccine was a collective effort, from national leadership by President Franklin Roosevelt to those who worked alongside Salk in the lab and the volunteers who rolled up their sleeves to be experimentally inoculated. </p>
<p><a href="https://www.youtube.com/watch?v=Jp9V2p40kKw">Sidney Busis</a>, a young physician at the time, performed tracheotomies on two-year-old children, making an incision in their necks and enclosing them in iron lung to artificially sustain their breathing. His wife Sylvia was terrified that he would transmit polio to their two young sons when he came home at night. </p>
<p>In the Salk lab, a graduate student, Ethyl “Mickey” Bailey, pipetted by mouth – pulling liquid up thin glass tubes – live polio virus as part of the research process. </p>
<p>My own neighbor, Martha Hunter, was in grade school when her parents volunteered her for “the shot,” the experimental Salk vaccine that no one knew if it would work. </p>
<p><a href="https://www.history.com/this-day-in-history/franklin-roosevelt-founds-march-of-dimes">President Roosevelt,</a> who kept his own paralysis from polio hidden from the public, organized the nonprofit National Institute of Infant Paralysis, later known as the March of Dimes. He encouraged every American to send dimes to the White House to support treating polio victims and researching a cure. In the process, he changed American philanthropy, which had been largely the domain of the wealthy.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=491&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=491&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=491&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=617&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=617&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321992/original/file-20200320-22598-1ctts2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=617&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Thousands of March of Dimes contributions were delivered to the White House in 1938.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/marguerite-missy-lehand-fdrs-secretary-opening-249571306">Everett Historical/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>That was a time, said Salk’s oldest son, Dr. Peter Salk, in an interview for our film, when the public trusted the medical community and believed in each other. I believe that’s an idea we need to resurrect today. </p>
<h2>What it took to end polio</h2>
<p>Jonas Salk was 33 when he began his medical research in a basement lab at the University of Pittsburgh. He had wanted to work on influenza but switched to polio, an area where research funding was more available. Three floors above his lab was a polio ward filled to capacity with adults and children in iron lungs and rocking beds to help them breathe. </p>
<p>There were many false leads and dead ends in pursuing remedies. Even President Roosevelt traveled to Warm Springs, Georgia, believing that the water there might have curative effects. While most in the scientific community believed that a <a href="https://doi.org/10.5501/wjv.v1.i4.108">live polio virus vaccine</a> was the answer, Salk went against medical orthodoxy. </p>
<p>He pursued a <a href="https://www.sciencehistory.org/historical-profile/jonas-salk-and-albert-bruce-sabin">killed virus vaccine</a>, trying it first on cells in the lab, then monkeys and, next, young people who already had polio. There were no guarantees this would work. Ten years earlier, a <a href="https://www.passporthealthusa.com/2019/06/how-was-the-polio-vaccine-developed/">different polio vaccine</a> had inadvertently given kids polio, killing nine of them.</p>
<p>In 1953, Salk was given permission to test the vaccine on healthy children and began with his three sons, followed by a vaccination pilot study of 7,500 children in local Pittsburgh schools. While the results were positive, the vaccine still needed to be tested more widely to gain approval. </p>
<p>In 1954, the March of Dimes organized a national field trial of 1.8 million schoolchildren, the <a href="https://doi.org/10.1136/bmj.317.7167.1233">largest medical study in history</a>. The data was processed and on April 12, 1955, six years from when Salk began his research, the Salk polio vaccine was declared “safe and effective.” Church bells rang and newspapers across the world claimed “Victory Over Polio.” </p>
<h2>Vaccinations and global health security</h2>
<p>In adapting our documentary for broadcast on the <a href="https://www.huffpost.com/entry/a-shot-to-save-the-world_b_4151327">Smithsonian Channel</a>, we interviewed Bill Gates, who explained why the Bill and Melinda Gates Foundation had made eradicating polio worldwide a <a href="https://www.npr.org/2011/01/31/133377748/bill-gates-goal-get-rid-of-polio-forever">top priority</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Jp9V2p40kKw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The polio vaccine was developed through the painstaking work of Jonas Salk and public efforts to fund research.</span></figcaption>
</figure>
<p>Vaccines, he said, have <a href="https://www.youtube.com/watch?v=JZvpF6gaGH4">saved millions of lives</a>. He joined the World Health Organization, UNICEF, Rotary International and others to help finish the job started by the Salk vaccine, eradicating polio in the world. This accomplishment will free up resources that will no longer have to be spent on the disease. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321988/original/file-20200320-22606-fyfgji.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">A health care worker delivers an oral dose of the polio vaccine.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Pakistan-Polio/61871c83bfc4446cba55f55c0ebfeffc/166/0">AP Photo/K.M. Chaudary</a></span>
</figcaption>
</figure>
<p>Up until now, <a href="https://ourworldindata.org/smallpox-is-the-only-human-disease-to-be-eradicated-heres-how-the-world-achieved-it">smallpox</a> is the only infectious disease we have ever eliminated. But <a href="http://polioeradication.org/news-post/five-ways-the-fight-against-polio-is-a-fight-against-other-diseases/">the global infrastructure</a> that the polio eradication effort has put in place is helping to fight other infectious diseases also, such as Ebola, malaria and now coronavirus. On Feb. 5, 2020, the Bill & Melinda Gates Foundation announced it would <a href="https://www.gatesfoundation.org/Media-Center/Press-Releases/2020/02/Bill-and-Melinda-Gates-Foundation-Dedicates-Additional-Funding-to-the-Novel-Coronavirus-Response">provide US$100 million</a> to improve detection, isolation and treatment efforts and accelerate the development of a vaccine for the coronavirus. </p>
<p>These are frightening times as the coronavirus spreads in ways reminiscent of poliomyelitis. It’s instructive to remember what it took to nearly eradicate polio and a reminder of what we can do when faced with a common enemy. On Oct. 24, 2019, <a href="https://www.vox.com/2019/10/24/20930553/polio-outbreak-2019-eradication-who">World Polio Day</a>, WHO announced there were only 94 cases of wild polio in the world. The success of the polio vaccine launched a <a href="https://doi.org/10.1073/pnas.1704507114">series of vaccines</a> that negated many of the effects of infectious disease for the second half of the 20th century.</p>
<p>At the end of our film, Salk’s youngest son, Dr. Jonathan Salk, recounted how his father wondered every day why we couldn’t apply the spirit of what happened with the development of the polio vaccine to other problems, such as disease or poverty. In fighting coronavirus, perhaps the citizens and governments of the world will rise to the occasion and demonstrate what is possible when we work together. </p>
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<p class="fine-print"><em><span>Carl Kurlander has previously received funding for the film from the R.K. Mellon Foundation, the Pittsburgh Foundation, the Elsie H. Hillman Foundation, The Burke Foundation, and the Jewish Healthcare Foundation for the making of the polio film as well as from the University of Pittsburgh. He is not current receiving any grant funding.
</span></em></p>Polio was nearly eradicated with the Salk vaccine in 1955. At the time, little was known about this mysterious disease that paralyzed and sometimes killed young children.Carl Kurlander, Senior Lecturer, University of PittsburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1215982019-09-13T11:37:14Z2019-09-13T11:37:14ZA newly designed vaccine may help stamp out remaining polio cases worldwide<figure><img src="https://images.theconversation.com/files/292096/original/file-20190911-190007-1t409cv.jpg?ixlib=rb-1.1.0&rect=272%2C13%2C1870%2C1387&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The oral polio vaccine is most commonly used in the developing world, despite one big problem.</span> <span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=18249">CDC/Alan Janssen, MSPH</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Public health organizations around the world have been fighting for global eradication of polio since 1988. Through massive vaccination efforts, the <a href="http://polioeradication.org/polio-today/history-of-polio/">incidence of polio has gone down 99%</a> since then, with the virus eradicated from most of the countries on Earth.</p>
<p>But there have been many setbacks.</p>
<p>One particularly serious threat has surfaced over the last 15 years. Among poorly vaccinated populations, an increasing number of polio cases are due to strains of the virus that originate from one version of the vaccine itself. The Sabin vaccine, which is taken orally, is <a href="https://www.who.int/biologicals/areas/vaccines/poliomyelitis/en/">composed of live but weakened viruses</a> that won’t sicken recipients but will still create lasting immunity against polio.</p>
<p>However, through genetic changes, the weakened vaccine virus can reacquire the ability to cause paralytic polio. How this happens and how to prevent it are under active research. A new vaccine deliberately constructed to prevent the poliovirus from regaining virulence may be the answer.</p>
<h2>Virus in vaccines, attenuated or killed</h2>
<p>The <a href="https://www.who.int/en/news-room/fact-sheets/detail/poliomyelitis">virus that causes polio</a> infects the cells of the throat and intestine. People usually catch it by ingesting food or water contaminated with fecal matter from an infected person.</p>
<p>Most people infected with the polio virus have no symptoms at all; about a quarter of infections result in flu-like symptoms. However, in about 1 out of every 200 cases, the virus <a href="https://doi.org/10.1016/j.virol.2005.09.015">invades the cells of the central nervous system</a>, causing paralysis.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=594&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=594&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=594&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=746&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=746&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292094/original/file-20190911-190050-1xdqj0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=746&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Illustration of a poliovirus particle.</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=22498">CDC/ Sarah Poser</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Poliovirus is a very simple virus. It is composed of a shell, or capsule, made of protein. Inside the capsule is a single strand of ribonucleic acid, or RNA, that encodes the genetic information to make new virus particles. There are three poliovirus strains – PV1, PV2 and PV3. Immunity to one strain does not confer immunity to the other two, so both the original Salk and Sabin vaccines included all three.</p>
<p>The Salk vaccine, which is injected, is composed of killed viruses; the Sabin vaccine, taken orally, contains live but weakened viruses. Such weakened vaccine viruses are known as “attenuated.” The oral vaccine is both more effective and easier to administer than the injected vaccine, and so it has been the primary weapon for worldwide eradication of polio.</p>
<p>Once a child is immunized with the oral polio vaccine, the weakened virus lives in their intestine for several weeks, allowing the child to develop immunity by building up antibodies. During this time, recipients shed live viruses in their feces. The weakened viruses in the vaccine itself do not cause polio, and this shedding can help to <a href="http://polioeradication.org/polio-today/polio-prevention/the-vaccines/opv/">immunize unvaccinated people</a> that come into close contact with recently vaccinated individuals. </p>
<p>But shortly after the oral vaccine became widely used in the early 1960s, researchers discovered that some shed viruses had <a href="http://www.virology.ws/2015/09/10/why-do-we-still-use-sabin-poliovirus-vaccine/">reacquired the ability to cause paralysis</a>.</p>
<p>As the viruses multiply in the intestine, they undergo genetic changes, some of which can reverse or circumvent the original genetic changes that had made them less virulent. These vaccine-derived virulent viruses very rarely cause their vaccinated host to get polio, but, when they circulate in the population, they put unvaccinated individuals at grave risk.</p>
<p>Because of this risk, most developed countries, including the United States, have <a href="https://www.cdc.gov/vaccines/vpd/polio/public/index.html">stopped using the oral Sabin vaccine</a>, relying instead on several injections of the Salk vaccine. However, oral polio vaccine is still the most available, and reliable, vaccine in developing countries.</p>
<h2>Fine-tuning the vaccination effort</h2>
<p>One of the polio strains – type 2 polio, or PV2 – was <a href="http://polioeradication.org/news-post/global-eradication-of-wild-poliovirus-type-2-declared/">declared eradicated</a> worldwide in 2015. The challenge then became preventing new cases of type 2 polio that could stem from virus shed by newly vaccinated people. </p>
<p>To prevent these new cases of vaccine-derived type 2 polio, the World Health Organization campaigned to replace the standard oral polio vaccine with one consisting of only PV1 and PV3. This <a href="https://www.who.int/immunization/diseases/poliomyelitis/en/">switch was completed in 2016</a>. </p>
<p>Unfortunately, the vaccine-derived type 2 poliovirus continues to circulate and cause paralytic polio. Globally, <a href="http://polioeradication.org/polio-today/polio-now/this-week/">104 polio cases due to this virus occurred in 2018</a>, which was three times the number of cases due to wild viruses not derived from the vaccine. As the number of children who have no immunity to type 2 poliovirus increases, this number may rise.</p>
<p>Health officials are campaigning to eliminate all oral vaccines and rely on injected vaccines containing killed virus. However, this plan imposes logistic and financial burdens on developing countries. Meanwhile, oral type 2 vaccines are needed to stop any outbreaks of type 2 polio. And health officials have not yet figured out how to make sure unvaccinated children don’t get polio from mutated viruses shed by vaccinated people.</p>
<h2>Ensuring virulence can’t be restored</h2>
<p>But what if researchers created a vaccine from a weakened live virus that’s unlikely revert to virulence? That’s one of the strategies that <a href="https://doi.org/10.2217/fmb-2019-0196">several research groups</a> are working on now.</p>
<p>As part of this effort, scientists have now mapped out in detail the <a href="https://doi.org/10.1016/j.cell.2017.03.013">steps that allow the PV2 vaccine strain to regain virulence</a>. </p>
<p>Just three simple genetic mutations, each of which alone has a small effect, when combined, dramatically increase the virulence of the PV2 strain in mice in the lab. And, all three are found in the viruses shed by <a href="https://doi.org/10.1016/j.cell.2017.03.013">recent vaccine recipients</a>.</p>
<p>Virulence can also be reestablished in the intestine if the genetic material of the PV2 strain recombines with that of another virus. The second virus can be the weakened PV1 or PV3 from the vaccine, <a href="https://doi.org/10.1016/j.cell.2017.03.013">or a related virus</a> such as coxsackie, a common virus in children.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=479&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=479&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=479&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=601&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=601&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292101/original/file-20190911-190050-1or0jb1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=601&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rather than making the vaccine from purified virus as Albert Sabin did, today’s researchers are tweaking the virus they will use to create the vaccine.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Watchf-Associated-Press-Domestic-News-Ohio-Unit-/486be8a50c8f406a9ece810ead1dee5d/156/0">AP Photo/Gene Smith</a></span>
</figcaption>
</figure>
<h2>Designing the virus for the vaccine</h2>
<p>Having discovered exactly how the type 2 vaccine virus regains virulence, scientists figured out ways that these specific genetic changes could be prevented. Using the tools of molecular biology, <a href="http://dx.doi.org/10.2139/ssrn.3400856">they made four important changes to the PV2 genome</a> that should stop it from regaining virulence.</p>
<p>Part of the virus’s RNA genome has to fold up into a lollipop-like shape in order for proteins to be made. This structure is disrupted in the weakened vaccine strain, but a single mutation in the virulent strain allows it to reassemble. So that can’t happen, the scientists changed the genetic sequence of the RNA in a way that no single nucleotide change would let the RNA fold into the stable lollipop structure again.</p>
<p>Second, they changed the genetic sequence of the enzyme that copies the RNA to make it more accurate. That way fewer genetic mutations would occur in the vaccine recipient’s intestine. </p>
<p>Third, another change to the same enzyme reduced the chance that the virus could pick up genes by recombining with other viruses in the recipient.</p>
<p>And, fourth, they rearranged the virus’s genes so that replacing certain regions of its own RNA with genetic information from a wild virus, such as coxsackie, would be lethal for it.</p>
<p>Researchers have produced two candidate PV2 viruses that grew well in experimental cells, were not virulent in a mouse model and were genetically stable. <a href="https://doi.org/10.1016/S0140-6736(19)31279-6">A phase 1 clinical trial of vaccines made from these viruses</a> showed that they were well tolerated, produced an immune response and had reduced (but not zero) reversion to virulence compared to the original oral vaccine for PV2.</p>
<p>These and other new, <a href="https://doi.org/10.1371/journal.ppat.1003001">rationally designed viruses</a> have the potential to provide good protection from polio with a reduced risk of creating new outbreaks due to circulating vaccine-derived polio virus.</p>
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<p class="fine-print"><em><span>Patricia L. Foster receives funding from the US Army Research Office. She is a member of the Union of Concerned Scientists and Concerned Scientists at Indiana University.</span></em></p>A challenge in eradicating polio comes from a version of the vaccine itself, which relies on live but attenuated virus. Rationally designing a new vaccine could help get rid of polio once and for all.Patricia L. Foster, Professor Emerita of Biology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.