Polio is back in the US and UK. Here’s how it went

The discovery that polio has partially paralyzed a young man from a New York suburb feels tired, but shocking. Tiring, because it is the third highly infectious virus to make landfall in the United States in three years, after monkeypox and SARS-CoV-2. And shocking because, for decades, polio hasn’t spread in wealthy countries, where sanitation, immunization and strong public health funding are supposed to keep people safe. Transmission was eliminated in the United States in 1979, in all of the Americas in 1994, and in the United Kingdom in 2003. And yet there it was, in sewage from the county where the young man lives and from a neighbor, in New York, and also in London.

Of course, poliomyelitis 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 was never contained, and 21 others where it bounced.

Disease experts, however, were not surprised to see it reappear in Western countries. For years, they have watched protection against the disease being undermined by funding cuts, vaccine hesitancy, forgetfulness and the cunning nature 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 said that until we can eradicate this completely, we are all in danger.”

Public health experts consider this an emergency, as cases of polio paralysis represent the tip of an immunological iceberg: for every person paralyzed, at least several hundred others have likely carried asymptomatic infections, providing a haven for the virus to replicate and spread. That takes time. The sewage findings show that polio may have 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 all children aged 9 or under, and why their counterparts in New York, where 40% of children in some postal codes are not vaccinated—have urged parents bring children for photo shoots. “The best way to prevent paralytic poliomyelitis is to get the poliovirus vaccine, 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 at Anschutz, who studies neurology. – invasive diseases. “If you are not vaccinated, or your children are not vaccinated against poliomyelitis, and the poliovirus is circulating in your community, you are at risk of developing paralytic poliomyelitis.”

To understand how polio ended up in these cities, it helps to review history a bit. Two stories, in fact: one for the polio vaccine, and one for how it was deployed to drive the disease out of the world.

Start with the vaccine formula – or formulas, actually, because there are two. They were born out of a fierce rivalry in the mid-twentieth century between scientists Jonas Salk and Albert Sabin. Salk’s formula, the first approved, is injected; it uses an inactivated version of the virus and protects against disease development, 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, as it is a liquid that is squirted into a child’s mouth, it is cheaper to manufacture and easier to distribute, as it does not require trained health personnel or careful disposal of needles. These qualities made the Sabin oral version, known as OPV, the bulwark in the fight against poliomyelitis, and ultimately the main weapon in the global eradication campaign.

Polio is back in the US and UK. Here’s how it went

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