January 30, 20258 min readPolio Vaccines Saved America from the Disease. What Happens if We Lose Them?Polio, a disease that can cause lifelong paralysis, has been eliminated from the U.S. Experts fear a resurgence if lifesaving vaccines are revoked under the new administrationBy Tara Haelle edited by Lauren J. YoungA healthcare worker gives an oral vaccine to a child as part of the National Pulse Polio Immunization Campaign on March 3, 2024 in Srinagar, India. Umer Qadir/Eyepix Group/Alamy Live NewsEvery aspect of Grace Rossows life since she was around nine months old has been affected by polio. The vaccine-preventable gastrointestinal disease attacks the nervous system and can cause death or lifelong paralysis in severe cases. For Rossow, a 32-year-old surgery case coordinator in Springfield, Ill., the condition caused her to lose function in her entire left leg.Every time that I take a step, I have to think about it, she says. Her brain runs through every possibility: Is her leg going to slip out from under her? Is her knee going to buckle? Is she going to hurt herself? Its almost like a mental triage, Rossow adds.Rossow gets around using either her $30,000 leg brace or a $4,000 wheelchair. The medical gear is on top of 15 surgeries and other procedures that have cost more than $1 million. But Rossow considers her situation fortunate; her adoptive parents brought her from India to the U.S., where she received health care that few polio survivors around the world can access.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.There is no cure for polio. The only treatment available is supportive care. The most effective way to fight polio is the vaccine that prevents ita tool that almost immediately began reversing the course of the disease in the U.S. Until the vaccine, polio outbreaks paralyzed more than 15,000 people, mostly children, annually but decreased to less than 10 a year in the 1970s. Experts say that the virus can return on a large scale, however. It wouldnt take much for the disease to do so and begin spreading the same terror it once did in U.S. communities more than a half century ago.I shudder to think about this, says Patsy Stinchfield, a pediatric nurse practitioner and immediate past president of the National Foundation for Infectious Diseases.Currently, she says, the U.S. has a highly immunized population, good disease surveillance and a strong public health response to isolate cases that emerge. There has also been high uptake of a highly effective vaccine that uses an inactivated (killed) virus; approximately 93 percent of U.S. children nationally are vaccinated against polio by age two. But if those layers of protection change, thats the recipe for a polio outbreak, Stinchfield says.Its pockets of the unimmunized that can bring diseases back. Patsy Stinchfield, former president of the National Foundation for Infectious DiseasesStinchfield is among the many public health experts who have concerns that the new Trump administration appointees might endorse policies and messaging that will weaken defenses against an outbreak. Robert F. Kennedy, Jr., an environmental lawyer whom President Donald Trump has nominated to lead the nations Department of Health and Human Services, has falsely suggested that the polio vaccine cost more lives than it saved, as noted in the New York Times. In addition, one of his closest advisors, lawyer Aaron Siri, petitioned the U.S. Food and Drug Administration on behalf of the Informed Consent Action Network (ICAN) in 2022 to withdraw or suspend its approval of IPOL, the brand name for the standalone inactivated poliovirus vaccine (IPV) available in the U.S. (Although combination polio vaccines exist and were not the subject of the petition, they also contain IPV.)Regardless of how the FDA ultimately responds, such petitionsincluding one from Siri, representing ICAN, to pause distribution of 13 other childhood vaccinesand related lawsuits can erode trust in vaccines, says Paul Offit, an infectious disease pediatrician and director of the Vaccine Education Center at Childrens Hospital of Philadelphia. Kennedy and his team did not respond to requests for comment. Siri and his team also did not respond to a request for comment by the time of publication.Trump has promised that people would not lose access to polio vaccines. But hes endorsed several other health-related appointees who have made past statements conveying doubt about different recommended vaccines. Trumps nominee for director of the Centers for Disease Control and Preventionphysician and former congressional representative of Florida David Weldonhas promoted inaccurate information about vaccines, including the widely debunked claim that they cause autism. Weldon and his team did not respond to a request for comment by the time of publication.A resurgence in polio wouldnt just affect unvaccinated individuals. Risk for infection would spike for vulnerable groups, including babies too young to be vaccinated and the estimated 17 million immunocompromised adults who cannot be vaccinated or would remain susceptible despite vaccination.Pediatric vaccination rates took a hit during the COVID pandemic, when millions of missed routine doctors visits lowered national immunization rates. Many families are now getting caught up on vaccines, but data shows that antivaccine misinformation that increased during the pandemic continues to counteract those gains in vaccine uptake. In the 20112012 school year, 1.2 percent of American kindergarteners nationwide had a nonmedical exemption from vaccines required for school, but that number has been rising. In the 20232024 school year, 3.3 percent of kindergarteners had an exemptionnearly all of which were nonmedicalfrom one or more vaccines required for school. The rate is the highest in recent history.Any attempts to withdraw an FDA approval of a vaccine would need to prove it is not safe or not effective and would likely face manufacturers lawsuits. But if Kennedy becomes HHS secretary, he would have broad powers over the CDCs vaccine messaging and policy, including the ability to revoke the agencys vaccine recommendations.Iron lungs lined up in the Ranchos Los Amigos Respiratory Center, Los Angeles, CA, 1950.Bettmann/Getty ImagesWhy Polio Could Still Enter the U.S.A populations protection against polio outbreaks is largely influenced by herd immunitythe threshold at which a large enough proportion of people are immune to a disease from vaccination or infection. A herd immunity level of about 80 percent is necessary to sustain protection against polio in a community, according to the World Health Organization.Its pockets of the unimmunized that can bring diseases back, Stinchfield says. If you have a community of people geographically close to each other and they all choose not to vaccinate, that community immunity is going to drop quickly. And if a person who has polio or is shedding polio enters that community, the spread will be much more rapid.Since the development of the first polio vaccine in 1955, there have been two options for immunization: an inactivated, or killed virus, vaccine and an oral polio vaccine containing weakened live versions of all three types of the virus found in the wild. The oral vaccine, which was discontinued in the U.S. in 2000, is more effective at achieving herd immunity because people shed the virus in their feces and saliva, and those who dont receive the vaccine may come in contact with the weakened viruses and develop antibodies against polio. The problem with the oral vaccine is the occasional instability of the virus.As the virus from the vaccine is shed from person to person, it can mutate and regain the neurovirulence [ability to attack the nervous system] and transmissibility of the wild virus, says Offit. In other words, the weakened virus can revert to a contagious, paralytic form that can cause polio in unvaccinated people.One of the biggest causes of polio outbreaks today is from such a virusknown as vaccine-derived poliovirus type 2 (VDPV2)which began spreading more widely after many countries started to use a newer version of the vaccine that did not protect against wild type 2 poliovirus. People were left unprotected from it, and existing undetected transmission of VDPV2 just intensified, Offit says, causing a resurgence of type 2 infections.VDPV2 infections cause paralysis in about 300 to 500 people globally each year. An updated oral vaccine has a more stable type 2 virus that rarely reverts to its paralytic form, but VDPV2 continues to be detected in wastewater in countries around the world, including European countries that havent seen polio cases in decades. Outbreaks in places that have already eliminated polio, such as the Gaza outbreak last summer, are caused by VDPV2.People think that polio is gone, but that virus is not gone. Paul Offit, director, Vaccine Education Center at Childrens Hospital of PhiladelphiaThe inactivated polio vaccine does not carry this risk but is less effective at community-level protection. Its best used to maintain control of polio in countries where its already eliminated, such as the U.S. But people who receive the inactivated vaccine are only protected against diseasedeveloping symptoms or paralysisnot against infection or transmission, explains James Cherry, a professor of pediatrics at the University of California, Los Angeles. That means the virus can cause an asymptomatic infection in someone whos had the inactivated vaccine. That person could then shed the virus in their feces for three to six weeks and in their saliva for up to two weeks.Enough of that circulation could potentially cause an outbreak if it reached vulnerable and unvaccinated individuals, Cherry says, who knows firsthand what that looks like. He remembers caring for polio patients as a young doctor in the late 1950sand even sometimes manually operating the iron lung (mechanical ventilator) that enabled patients to breathe when the virus had paralyzed their breathing muscles.It comes on suddenly, its highly, highly contagious, and its entirely preventable, says Linda Lindeke, a retired nursing professor at the University of Minnesota. She lost her best friend, Sandra, in first grade to polio in 1954, inspiring her to become a pediatric nurse practitioner. Children should not die the way Sandra did, Lindeke says.In addition to VDPV2, wild type 1 could potentially cause outbreaks in the U.S. It is currently circulating in Afghanistan and Pakistan, but Stinchfield cautions that viruses dont know geographic borders. Lindeke and other health professionals fear that growing public distrust of vaccines may cause polio vaccination rates to fall, opening the door to wild type 1 or vaccine-derived cases to seed outbreaks.How Polio Outbreaks Could ReturnNo one at the orphanage Rossow lived at knew how she contracted polioshe was the only child with symptomsbut thats the nefarious nature of polio. About 70 percent of people infected with the disease never show any symptoms. Others have flulike symptoms, and up to 5 percent develop meningitis, but only one in 200 to 2,000 develop permanent paralysis, depending on the virus type.A paralytic case is the tip of the iceberg, says Walter Orenstein, former associate director of the Emory Vaccine Center at Emory University. There could be hundreds or over 1,000 people already infected at the time you see a paralytic case. By the time a paralytic case occurs, widespread transmission is likely already occurring; large-scale vaccination efforts would be needed to stop it, he adds.Further, its impossible to track who is infected and spreading the disease. In 2022 public health officials were unable to trace the source of infection of a man who developed paralytic polio in a highly unvaccinated community in Rockland County in New York State. They were also unable to determine if anyone else might have been infected. Polio can linger in the environment for months. The polio type the Rockland County resident contracted was initially detected in the wastewater of Rockland and a neighboring county. Between March and October of that year, 89 wastewater samples from at least four additional New York State counties tested positive for poliovirus.Every time that I take a step, I have to think about it. Grace Rossow, polio survivorOffit suspects VDPV2 could already be circulating undetected in the wastewater of some major U.S. cities. A CDC spokesperson said wastewater testing for polio is not routinely done in the U.S., though it can be done in at-risk communities as needed.People think that polio is gone, but that virus is not gone, Offit says. It could be circulating in pockets of the U.S. right now, with cases being prevented only by high vaccination levels. But if those levels drop dramatically, we might not realize the dangers until its too late.If we stop vaccinating today, we probably wouldnt have outbreaks tomorrow because it would take some time for susceptible people to accumulate, Orenstein says. So some of the anti-vaxxers could say, See? We didnt need vaccines. But then as susceptible [people] accumulate and we get introductions of these pathogens, we will see outbreaks.Highly immunized communities are the defense, Orenstein adds. The offense is finishing the job of eradicating polio.