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

But removing type 2 from the formula meant that if a type 2 virus reappeared in the world – from an environmental reservoir or someone whose system harbored a mutated vaccine virus – there would be little defense against it. . And the switch bet didn’t pay off.

“I think the best way to describe this is an honest mistake,” says Svea Closser, a medical anthropologist and associate professor at the Johns Hopkins Bloomberg School of Public Health who studies polio eradication. “They did not expect the scale, spread and global reach of these type 2 outbreaks.”

Most of the vaccine-derived viruses circulating today are type 2 mutated. It has mainly appeared in Central Africa, where epidemics have spread beyond national borders. The polioviruses found in New York and London are also type 2 mutated. It is important to note that although these two viruses are related to each other – and to the vaccine-derived viruses found earlier in Israel – there is as yet no genomic evidence that they are related to the viruses. Africans. They have fewer genetic changes from the vaccine virus than those circulating in Africa, indicating that they emerged more recently. They were probably imported from somewhere that used OPV in the past (like Israel did in the 2000s) or continue.

This matters, and not just because these Type 2 viruses may have emerged from the misplaced optimism of the Switch. Generally accepted data on the incidence of poliomyelitis – around one case of paralysis per 200 infections – come from research on type 1. Some data suggest that the figures for type 2 are different: one case of paralysis per 2,000 infected people. So if one New Yorker is paralyzed, thousands could spread the virus unknowingly. Add to that clusters of neighborhoods with low vaccination rates, and the area could be more vulnerable than people realize.

“It always comes down to vaccination coverage,” says John Vertefeuille, epidemiologist and branch chief for polio eradication at the US Centers for Disease Control and Prevention. “In this area of ​​New York, vaccination coverage is not as high as in much of the US population, and the first detections in London were in places where vaccination coverage was lower than what you would see. usually.”

It is difficult to imagine how society ceased to fear this disease. There are living politicians and celebrities who endured polio as children: Senate leader Mitch McConnellfor example, and singer Joni Mitchell, who also suffered a severe recurrence in 1995. The panic poliomyelitis that the closing of schools and theaters and the emptying of swimming pools in the 1950s happened during the lifetimes of baby boomers. “The fact that we need everyone to be vaccinated was well accepted at one point; people were lining up in the streets to get their polio vaccine and their measles-mumps-rubella shots,” says Howard Forman, a physician and health policy expert and professor at Yale School of Medicine. “Over time, I think people’s memories have faded. I think most people today probably don’t understand polio.

If there is a benefit to the emergency, it may be that it has brought the persistent threat and unpredictable risks of polio back into the consciousness of people in wealthy countries. For the international campaign to end the disease, this can only be good. The campaign is a joint effort of the CDC, the World Health Organization, UNICEF, the Bill and Melinda Gates Foundation and millions of volunteers from the service organization Rotary International. Since last year, it has deployed a OPV reworked, just for type 2, which is less likely to cause mutations. Even with these sponsors, however, the campaign is chronically short of money. A new awareness could change that.

“Detections in London and New York have already drawn attention to polio and VDPVs,” ​​or vaccine-derived polioviruses, says Carol Pandak, epidemiologist and global health expert director of Rotary’s PolioPlus program. “They also underscore the urgency of stopping both wild polio and vaccine-derived polio, as many more people now understand that VDPVs can cause paralysis just like wild poliovirus. They starkly remind us that as long as poliomyelitis exists anywhere, it is a threat everywhere.

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