Polio case in New York, is the goal of eradication in danger?


No polio scholar knew more than Albert Sabin, the Polish-American University of Cincinnati scientist whose vaccine against the crippling disease has been in use around the world since 1959.

Sabin’s oral vaccine provides lifelong immunity. It has a downside, which Sabin, who died in 1993, fiercely refused to acknowledge: In rare cases, the weakened live poliovirus in the vaccine can mutate, regain virulence, and cause polio.

Those rare mutations — one of which appears to have paralyzed a young man from Rockland County, New York, a member of the Hasidic Jewish community who resists vaccination, according to the official report — have taken center stage in the global campaign. to eradicate polio, the largest international public health effort in history.

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

By 2015, polio had been almost completely eradicated everywhere except Pakistan and Afghanistan. But by 2020, cases had been reported in 34 countries, mainly in sub-Saharan Africa and Asia.

Although the numbers have decreased in the last 18 months, some cases have emerged in Ukraine and Israel; In June, the polio virus was detected in London sewage, and now the case north of New York City, the first in the United States since 1993.

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

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Almost all other cases in the world, paradoxically, stem from mutations in the weakened virus that is part of the vaccine. Sabin designed the vaccine virus to infect people’s intestines without making them sick, but in rare cases, this virus mutates in the intestine.

In these cases, it goes in like a lamb but comes out like a lion, capable of paralyzing unprotected people who ingest the virus as a result of poor hygiene, after contact with things like diapers or bath towels that contain traces of feces from a infected person.

The polio virus has three types. Type 2, the version that causes nearly all vaccine-associated cases of polio, paralyzes just 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.

Rockland County officials say her polio case may have been infected in the United States, but the virus must have originated in a country, usually in Asia or Africa, where the oral vaccine is still given. In the United States, since 2000, doctors have given a different vaccine, developed by Dr. Jonas Salk in 1955, that contains killed or inactivated poliovirus.

Since a polio infection rarely results in paralysis, the Rockland County case suggests that other people in the community may be carrying the virus. Exactly how many are being investigated, said Beth Cefalu, a spokeswoman for the county health department.

If the patient acquired the virus in the United States, “it would suggest there could be substantial transmission at least in that area,” said Dr. Walter Orenstein, an Emory University professor who led the national vaccination program from 1988 to 2004. That puts pressure on the Centers for Disease Control and Prevention (CDC) to find the best way to stop these chains of infection, he added.

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As of Friday, July 29, county health officials had set up inactivated polio vaccine clinics and sent 3,000 letters to parents of children in the county whose routine immunizations, including polio, were not up to date.

However, although the Salk vaccine prevents paralysis and is highly effective in protecting a community from infection, in situations where polio circulates widely, a person immunized with this vaccine could still carry polio germs in their intestines. and spread them to other people.

Depending on the number of infected people in the community, the CDC might consider using a newer live vaccine product, known as the new oral polio vaccine 2, or nOPV2, which is less likely to mutate into a virulent form, he explained. Orenstein.

However, the new oral vaccine is not licensed in the United States and would require considerable red tape to be approved under emergency authorization, Orenstein said.

To further complicate matters, vaccine virus polio outbreaks increased, mainly in sub-Saharan Africa, after world health leaders declared that type 2 poliovirus had been eradicated from the wild and eliminated that type of virus. vaccine virus.

Unfortunately, the type 2 mutant forms that originated in the vaccine continued to circulate and outbreaks multiplied, Orenstein said. Although nearly 500 million doses of the new vaccine have been administered, according to Dr. Ananda Bandyopadhyay, polio program leader at the Bill & Melinda Gates Foundation, some areas with circulating mutant viruses have yet to start using the new vaccine.

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The chances of a major outbreak linked to the Rockland County case appear slim. The virus can only spread widely where there is low immunization coverage and poor surveillance of polio cases, said Dr. David Heymann, a professor of epidemiology at the London School of Hygiene and Tropical Medicine, and former director of the global effort. of polio eradication.

Rockland County has extensive experience fighting vaccine-preventable outbreaks. In 2018 and 2019, he battled a measles epidemic among the community of anti-vaccine Hasidic rabbis that resulted in 312 cases.

“Our people defeated measles and I am confident that we will also eliminate the new health problem,” County Commissioner Ed Daly said at a news conference Thursday.

Scientists believe polio can be eradicated from the entire world by 2026, Bandyopadhyay said, at a cost of $4.8 billion. Much of that sum has yet to be raised from donor countries and charities.

And he added that the case of polio in the United States offers a reminder “that polio is potentially a plane ride away while the virus still exists in some corner of the world.”

KHN (Kaiser Health News) is the newsroom of KFF (Kaiser Family Foundation), which produces in-depth health journalism. It is one of three major programs of KFF, a nonprofit organization that analyzes the nation’s health and public health issues.

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