The discovery that Polio has partially paralyzed a young man in a New York suburb and he’s feeling tired but shocking. Fatiguing because after monkeypox and SARS-CoV-2 it is the third highly infectious virus to make a surprise landing in the USA in three years. And shocking because polio has not spread in decades in wealthy countries where sanitation, immunization and solid public health funding are assumed to protect populations. The transmission was eliminated in the US in 1979, across America in 1994, and in the UK in 2003. And yet it was there, in the sewage of the district where the young man lives, and in a neighboring one, in New York City, and also in London.
Of course, polio also exists in other parts of the world. A worldwide campaign to eradicate it has been working on this arduous task since 1988. In the past year, poliovirus caused paralysis — which cannot be treated or cured — in two countries where it was never contained and in another 21 where it has returned.
However, disease experts were not surprised that it reappeared in western countries. For years, they have watched as protection from the disease has been eroded by funding cuts, vaccine hesitancy, forgetfulness and the insidiousness of the virus. “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 have said that until we can eradicate this completely, we are all at risk.”
Public health experts consider this an emergency because cases of polio paralysis represent the tip of an immunological iceberg: for every paralyzed person, at least several hundred more are likely to have asymptomatic infections, providing a haven for the virus to replicate and transmit. This will need time. Sewage findings show that polio may have been circulating in London since February and in New York for at least a few months.
This sense of urgency is why London health officials have offered booster doses to all children under the age of 9 and why their counterparts in New York City – where 40 percent of the children in some postcodes are not vaccinated – have asked the parents getting kids to shoot. “The number one way to prevent paralytic polio is to get vaccinated against the poliovirus, and the vaccine is over 99 percent effective in preventing paralysis,” said Daniel Pastula, physician and associate professor at the University of Colorado’s Anschutz Medical Campus , who researches neuroscience-invasive diseases. “If you are not vaccinated or your children are not vaccinated against polio and poliovirus is circulating in your community, you are at risk of developing paralytic polio.”
To understand how polio got into these cities, it helps to look back at history a little. Two stories, actually: one for the polio vaccine and one for how it was used to wipe the disease out of the world.
Start with the vaccine formula—or formulas, actually, because there are two. They arose from a wild rivalry in the mid-20th century between scientists Jonas Salk and Albert Sabin. Salk’s formula, the first to be approved, is injected; It uses an inactivated version of the virus and protects against disease development but does not stop virus transmission. Sabin’s formula, launched 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 produce and easier to distribute, as it doesn’t require trained medical staff or careful disposal of needles. These qualities made the oral version of Sabin, known as OPV, the bulwark of polio control and eventually the main weapon in the global eradication campaign.