Disease trackers are increasingly worried that cases of polio outside of New York City could mushroom into a wider problem.
A vaccine-derived form of polio was identified last month in Rockland County, New York, and it has been detected in sewage in neighboring Orange County and overseas in London.
Dr. Jose Romero, director of the CDC’s National Center for Immunization and Respiratory Diseases, said many people who get polio don’t show symptoms, so it could be spreading silently.
“There are a number of individuals in the community that have been infected with poliovirus. They are shedding the virus,” Dr. Romero told CNN. “The spread is always a possibility because the spread is going to be silent.”
A CDC team recently traveled to New York to investigate the situation in Rockland County, which has a shockingly low polio vaccination rate of about 60% compared to the nationwide rate of 93%.
The county is located in the southeastern corner of the state bordering New Jersey.
Polio is highly contagious and was a devastating disease in the early 20th century before the vaccine arrived.
There is a wild type that is only endemic to Afghanistan and Pakistan, though it was detected in Mozambique earlier this year.
But the CDC said the case in New York was a vaccine-derived poliovirus, or VDPV, in an unvaccinated person. A VDPV is a strain related to the weakened live poliovirus in the Sabin vaccine, also known as the oral polio vaccine (OPV).
“If allowed to circulate in under- or unimmunized populations for long enough, or replicate in an immunodeficient individual, the weakened virus can revert to a form that causes illness and paralysis,” the CDC said.
The OPV vaccine is no longer licensed in the U.S. though it is used in other parts of the world.
“To me, VDPV is a separate problem [from wild polio] that stems from the fact that much of the world still uses the Sabin vaccine which, in rare circumstances, can give rise to circulating VDPVs that can cause disease in susceptible unvaccinated individuals,” said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security.
The U.S. has been giving children the inactivated poliovirus vaccine (IPV) since 2000.
Children typically get a course of four shots for polio between 2 months old and 6 years old. Some groups, including some in the Orthodox Jewish community in Rockland County, have resisted vaccination, sparking calls for an information campaign.
Disease fighters are considering different steps to fight a potential outbreak, including whether extra doses are needed for certain persons. U.K. officials started offering boosters in the London area.
“The vaccination series for polio is a series of doses and is highly effective but not everyone is up to date and levels are low in parts of London which allows the VDPV the opportunity to cause disease,” Dr. Adalja said. “I think that places in the U.S. like Rockland County could also benefit from targeted vaccination to get individuals up to date.”
Public health experts said efforts to bolster vaccination rates should include enforcement of mandates that require the polio vaccine for school attendance and an effort to enlist members of the impacted communities. A measles outbreak in 2019 also hit members of the Orthodox Jewish community in Rockland County.
“I think there does need to be a coordinated vaccination strategy, and it is ideally led by members of that Orthodox Jewish community. Just as you have members of the gay community lead the messaging on monkeypox,” said Lawrence O. Gostin, a global health law professor at Georgetown University. “You go to the communities that are at greater risk and have the greater vulnerabilities and you use people who have influence and respect.”
• Tom Howell Jr. can be reached at thowell@washingtontimes.com.
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