Some ten thousand diseases afflict mankind, and we have the power to overcome only a handful. It is especially tragic, then, when we squander the opportunities we have, whether by choice, negligence, or incompetence. In June, a 20-year-old unvaccinated man from Rockland County, New York developed fever, abdominal pain and a stiff neck. A few days later, he was having trouble moving his legs. He checked himself into a nearby hospital, where he became the first person in nearly a decade to be diagnosed with polio in the United States. Poliomyelitis can be prevented, but not cured.
Since most cases of poliomyelitis do not cause paralysis, a single case of paralysis suggests that the virus may already be widespread. Public health officials say hundreds of people may have been infected and the virus is now spreading through New York City’s sewage. “I think it’s safe to assume that this case represents the tip of the iceberg,” José R. Romero, director of the National Center for Immunization and Respiratory Diseases, told me. The Centers for Disease Control and Prevention is calling the situation a public health emergency.
New York is not alone. The ancestral strain of polio has never been eradicated in Afghanistan or Pakistan and earlier this year, more than a year after Africa was declared polio-free, the virus crippled children in Malawi and Mozambique. (In 2011, the CIA staged a bogus hepatitis B vaccination campaign in Pakistan in an effort to find Osama bin Laden; revelations from the secret program subsequently destroyed confidence in vaccination and dozens of vaccinators been killed In Ukraine, poliomyelitis has paralyzed at least nineteen people this year In Israel, eight cases of poliomyelitis in children were reported in the spring In June, after the virus was detected in samples of sewage system, authorities declared a “national incident” and offered polio boosters to all children who live in the city and are between the ages of one and nine.
For those vaccinated, the virus poses little risk: a complete series of poliomyelitis vaccinations provides more than ninety-nine percent protection against systemic disease. Because ninety-three percent of children in the United States are vaccinated — well above the herd immunity threshold — we will see nothing like the horrific epidemics of the 20th century that paralyzed thousands of Americans. every year. Yet in communities where vaccination rates are low, the virus could cause far-reaching and entirely preventable damage. In Rockland County, home to a large Orthodox Jewish population targeted by anti-vaccine activists, only 60% of young children are vaccinated. In some postcodes, barely a third are. (Although every state requires polio vaccination to attend public schools, in some cases parents can get religious or personal exemptions, and many delay vaccinating their children until they start kindergarten. )
In the worst-case scenario, these outbreaks could be more than a temporary setback: they could undermine years of hard-earned progress that nearly eradicated the virus from the world. “I’m really worried that we’re seeing more cases,” Walter Orenstein, associate director of the Emory Vaccine Center who previously led the national immunization program, told me. “We cannot simply be reassured by high vaccination rates across the country because subpopulations with low coverage may sustain transmission.”
Poliovirus is extremely contagious and is usually spread through contaminated food or water. Once infected, a person can transmit the virus for more than a month, even if they are asymptomatic. The virus resides primarily in the gastrointestinal tract, but occasionally migrates to the central nervous system, where it can inflict devastating, sometimes permanent damage. Up to 5% of those infected will suffer from meningitis or inflammation of the protective membranes around the brain and spine; up to one in two hundred people will develop paralysis, usually of the legs, but sometimes of the muscles that allow us to breathe, resulting in respiratory collapse. (The world’s first intensive care units were developed, in the 1950s, to treat poliomyelitis.) Decades after an infection, up to half of survivors may experience progressive muscle weakness and pain, known as name of post-polio syndrome.
Unlike coronaviruses and monkeypox, poliovirus has no animal reservoir – it only infects humans. Because it cannot take refuge in other species, it is exceptionally vulnerable to eradication, and in recent years we have come considerably closer. In 1988, when the Global Polio Eradication Initiative was launched, there were approximately 350,000 cases of poliomyelitis a year in more than 100 countries; the virus paralyzed a thousand children a day. Since then, the incidence of poliomyelitis has decreased by 99.9%; in 2018, there were only one hundred and thirty-eight cases worldwide. The vaccination campaign would have avoided more than two million cases of paralysis.
Military conflicts, migration patterns and humanitarian crises have all contributed to the spread of polio, but fundamentally, vaccine-preventable diseases increase when vaccination rates drop. During the covid-19 pandemic, the world has seen its biggest drop in childhood vaccinations in three decades. In 2020, when dozens of countries experienced a months-long pause in polio vaccination efforts, at least eleven hundred children were crippled. In 2021, twenty-five million children missed at least one dose of routine immunization. Meanwhile, the anti-vaccine movement continues to gain traction.
“This really should be a call to action for parents,” New York City Health Commissioner Ashwin Vasan told me. “We are trying to sound the alarm here.” Vasan, whose uncle was paralyzed by poliomyelitis and whose aunt died of it, in India, said that “there is no doubt that the anti-science and anti-vaccine movements have grown in strength and visibility these last years. And now in social media they have a disinformation highway through which they can spread their message.
One response to global disinformation campaigns is hyperlocal action. Research suggests that decisions to get vaccinated may be less of an individual risk-benefit analysis, and more of social norms: when people believe others around them are getting vaccinated, they are more likely to get vaccinated. vaccinate themselves. Public health officials should recruit trusted figures from within communities who can respond directly to people’s questions and concerns. It may also be possible to immunize people against misinformation, with campaigns that train the public to recognize its many forms. Healthcare providers can try a technique known as motivational interviewing, which explores the reasons for a person’s ambivalence and guides them toward positive behavior change. In other cases, governments and clinicians need to reduce practical barriers to vaccination by making it accessible, convenient and free.
The history of polio vaccination, while remarkably successful overall, also includes an inconvenient truth: the majority of cases are now caused by “vaccine-derived polioviruses”, which evolved from a live vaccine. For decades, much of the developing world has depended on the oral polio vaccine, or OPV, invented by medical researcher Albert Sabin, which uses a weakened virus to generate an immune response. The vaccine is cheap, accessible and extremely effective: a dose costs a few cents and is administered by injecting a few drops into the mouth. Once immunized, people can shed the harmless virus, which, in areas with poor sanitation, can actually be a good thing: unvaccinated people are exposed to the non-threatening version and also gain immunity. But, in rare cases, if the weakened virus is able to circulate in underimmunized communities for an extended period, it can gradually mutate into a virulent form that causes disease. Genetic sequencing linked the case in New York and polio in sewage in Jerusalem and London to vaccine-derived poliovirus.