The discovery that Polio has partially paralyzed a young man in a New York suburb feels tired, but shocking. Tired, because it’s the third highly infectious virus to make surprise landfall in the US in three years, after monkeypox and SARS-CoV-2. And shocking because, for decades, polio has not spread to rich nations, where sanitation, vaccination and robust public health funding are supposed to keep populations safe. Transmission was phased out in the US in 1979, in all of the Americas in 1994, and in the UK in 2003. And yet there it was, in the sewage of the county where the young man lives and a neighbor in New York City, and also in London.
Of course, polio exists in other parts of the world. A global campaign to eradicate it has been working on this grueling task since 1988. Last year, the poliovirus caused paralysis—which cannot be treated or cured—in two countries where it has never been contained, and in 21 others where he recovered.
Disease experts, however, were not surprised to see it reappear in Western nations. For years they have watched as protection against the disease was undermined by funding cuts, vaccine hesitancy, forgetfulness and the virus’s cunning nature. “This should be a wake-up call for people,” says Heidi Larson, professor and founder of the Vaccine Confidence Project at the London School of Hygiene and Tropical Medicine. “We’ve been saying that until we can eradicate it completely, we’re all at risk.”
Public health experts consider this an emergency, because cases of polio paralysis represent the tip of an immunological iceberg: for every person paralyzed, at least a few hundred others have carried asymptomatic infections, providing a haven for the virus to reproduce and transmit. This takes time. The sewage findings show that polio has possibly been circulating since February in London and for at least several months in New York.
This sense of urgency is why health authorities in London have offered booster doses of the vaccine to any child aged 9 and under, and why their counterparts in New York City, where 40 percent of children in some zip codes they are not vaccinated—they have urged the parents to take the kids shooting. “The number one way to prevent paralytic poliomyelitis is to get vaccinated against the poliovirus, and the vaccine is more than 99 percent effective in preventing paralysis,” says Daniel Pastula, a physician and associate professor at the University of Colorado Anschutz Medical Campus. who studies neuro. -invasive diseases. “If you are not vaccinated, or your children are not vaccinated against polio and the polio virus is circulating in your community, you are at risk of developing paralytic polio.”
To understand how polio ended up in these cities, it’s helpful to review a little history. Two stories, in fact: one for the polio vaccine, and another for how it has been deployed to chase the disease around the world.
Start with the vaccine formula, or formulas, actually, because there are two of them. They were born out of a fierce mid-20th century rivalry between scientists Jonas Salk and Albert Sabin. Salk’s formula is injected, the first approved; it uses an inactivated version of the virus and protects against the development of disease, but does not stop viral transmission. Sabin’s formula, which came a few years later, used an artificially weakened live virus. It blocks transmission, and because it’s a liquid that’s injected into a child’s mouth, it’s cheaper to make and easier to distribute, as it doesn’t require trained healthcare personnel or careful disposal of needles. These qualities made Sabin’s oral version, known as OPV, the bulwark of polio control and ultimately the primary weapon in the global eradication campaign.