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What the Polio Case in New York Tells Us About the End of Polio

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No polio researcher knew more than Albert Sabin, a Polish-American scientist whose crippling disease vaccine has been used worldwide since 1959. The Sabina oral vaccine provides lifelong immunity. It has one flaw, which Sabin, who died in 1993, vehemently disputed: Rarely, attenuated live poliovirus in a vaccine can mutate, regain virulence, and cause polio.

These rare mutations — one of which appears to have paralyzed a young man from Rockland County, New York, who belongs to a vaccine-resistant Hasidic Jewish community, local officials said on July 21 — have taken center stage in a global campaign to eradicate polio. . the largest international public health effort in history.

When the World Health Organization-led campaign began in 1988, its goal was to rid the world of polio by the year 2000.

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By 2015, polio was nearly eradicated from everywhere except Pakistan and Afghanistan. But by 2020, cases had been reported in 34 countries, mostly in sub-Saharan Africa and Asia. Although numbers have declined over the past 18 months, a few cases have been identified in Ukraine and Israel, poliovirus was found in sewage in London last month, and now north of New York is the first U.S. case since 1993.

But the nature of the polio threat has changed. “Natural” or “wild” polio circulates only in a few war-torn areas of Pakistan and Afghanistan, where gunmen have killed dozens of polio vaccinators.

Paradoxically, almost all other cases in the world are due to mutations in the weakened virus that makes up the vaccine. Sabin developed the vaccine virus to infect people’s intestines without making them sick, but on rare occasions the vaccine virus mutates into a dangerous form when it passes through the intestines of a vaccinated person.

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In these cases, it enters like a lamb but exits like a lion, capable of paralyzing unprotected people who ingest the virus as a result of poor hygiene, after coming into contact with things such as diapers or bath towels that contain traces of the infected person’s feces. .

Poliovirus has three types. Type 2, the version that causes nearly all cases of vaccine-associated poliomyelitis, paralyzes only 1 in 1,000 people it infects. Others may not get sick at all or have typical viral symptoms such as a runny nose or diarrhea.

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Rockland County officials say their polio patient may have been infected in the United States, but the virus must have originated in a country that still makes oral polio vaccine, usually in Asia or Africa. In the United States, doctors have been administering another vaccine since 2000, a shot invented by Dr. Jonas Salk in 1955 that contains killed or inactivated polio viruses.

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Given how rarely a polio infection leads to paralysis, the Rockland County case suggests that other people in the community may be carriers of the virus. How many people are under investigation, said a spokeswoman for the Bet Cefalu County Health Department. Scientists have found poliovirus in the county’s sewage, but have no idea how many others are infected, Cefalu said in a July 26 press release.

If a patient contracted the virus in the United States, “it could mean that at least in this area there may have been serious transmission,” said Dr. Walter Orenstein, an Emory University professor who led the U.S. vaccination program from 1988 to 2004. The pressure is on the Centers for Disease Control and Prevention to find the best way to stop any chains of infections, he said.

As of July 22, county health officials have opened inactivated polio vaccine clinics and sent 3,000 letters to parents of children in the county whose routine immunizations, including polio shots, were not delivered on time.

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However, while the Salk vaccine prevents paralysis and is very effective in protecting the public from infection, in situations where polio is widespread, a person vaccinated by Salk can still carry polio germs in their intestines and pass them on to others.

Depending on the number of people infected in a community, the CDC may consider introducing a newer live vaccine, known as the new oral polio vaccine type 2 or nOPV2, which is less likely to mutate into a virulent form, Orenstein said.

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However, the new oral vaccine is not licensed in the United States and would require significant bureaucratic procedures to get approved under the emergency clearance, Orenstein said.

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To complicate matters further, vaccine virus outbreaks of polio have increased, mostly in sub-Saharan Africa, after world health leaders said type 2 poliovirus had been eradicated from the wild and they removed the type vaccine virus. Unfortunately, type 2 mutants derived from the vaccine continued to circulate and outbreaks grew like mushrooms, Orenstein said. Although nearly 500 million doses of the new vaccine have been administered, according to Dr. Ananda Bandyopadhyay, director of the polio program at the Bill & Melinda Gates Foundation, some areas with circulating mutant viruses have yet to start using the new vaccine.

The chances of a major outbreak associated with a case in Rockland County are low. The virus can only spread widely where vaccination coverage is low and polio case surveillance is poor, said Dr David Heymann, professor of epidemiology at the London School of Hygiene and Tropical Medicine and former director of the World Polio Eradication Organization.

Rockland County has experience with vaccine-preventable outbreaks. In 2018 and 2019, the district battled a measles epidemic among anti-vaccine followers of Hasidic rabbis.

“Our people have beaten measles, and I’m confident that we’ll fix the latest health problem as well,” County Executive Ed Daly said at a July 21 press conference.

Scientists believe that polio can be eradicated from the world by 2026, Bandyopadhyay said, but it will cost $4.8 billion, much of which has yet to come from donor countries and charities.

The U.S. polio case serves as a subtle reminder that “polio can potentially be airlifted while the virus still exists in some corner of the world,” he said.

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