New York emergency lands US on small list of countries with circulating poliovirus
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The CDC said Tuesday that the United States has joined a list of around 30 countries with circulating vaccine-derived poliovirus.
The announcement came days after New York Gov. Kathy Hochul declared a state disaster emergency to shore up resources and increase polio vaccination after poliovirus was detected in wastewater samples in four counties and New York City.
That, in addition to a previously announced case of paralytic polio in the state, were enough to meet WHO’s criteria for circulating vaccine-derived poliovirus (cVDPV), the CDC said.
Outbreaks of cVDPV occur when the weakened virus in the oral polio vaccine circulates among undervaccinated populations, allowing it to mutate and regain its ability to infect humans.
Poliovirus samples found in wastewater specimens from New York have been linked to samples found in Jerusalem and London, indicating community transmission, the CDC said.
The case of paralytic polio in an unvaccinated man from Rockland County, just west of New York City, remains the only confirmed case thus far. It was the first case of polio in the U.S. in nearly a decade.
The U.S. has not used oral polio vaccine since 2000.
“The virus was transported here, either from someone from the U.S. who traveled to a polio-affected area of the world or from a visitor who was in one of those affected areas,” Walter A. Orenstein, MD, associate director of the Emory Vaccine Center and an infectious diseases professor at Emory University, told Healio. “There has to be more infections, [although] not necessarily more paralytic cases.”
Risk assessment
Like wild poliovirus, vaccine-derived poliovirus can cause paralysis. However, evidence of polio in wastewater does not mean most people are at risk for illness, experts said.
Aaron E. Glatt, MD, chair of the department of medicine and chief of infectious diseases at Mount Sinai South Nassau in Oceanside, New York, told Healio that “not everybody who gets polio gets clinical illness.”
“The only people who would be susceptible are those who are unvaccinated,” Glatt said. “A vaccinated person, who is fully vaccinated, there’s no risk.”
Although most people are not at risk, New York State Health Commissioner Mary T. Bassett, MD, MPH, urged New Yorkers last week “not to accept any risk at all.”
Hochul’s emergency declaration “immediately expands the network of polio vaccine administrators” to include EMS workers, midwives and pharmacists, according to the state health department. The declaration also requires health care providers to share polio immunization data to help officials determine where vaccination efforts need to be focused.
Although 24% of people who acquire a poliovirus are symptomatic and less than 1% experience paralytic poliomyelitis, people who acquire the disease but are asymptomatic can still spread the virus to others, Orenstein said.
As of Sept. 9, the CDC has confirmed the presence of polioviruses in 57 water samples taken since April from Rockland, Orange, Sullivan and, most recently, Nassau counties, as well as from New York City, according to the state health department. Of these, 50 samples were genetically linked to the case of paralytic polio in Rockland County, although the state health department said the findings do not indicate that this person was the source of the transmission.
Bassett said last month that the department is treating the case as “just the tip of the iceberg of much greater potential spread.”
‘Cannot roll the dice’
Vaccination rates in children vary between the four counties, according to state health department, with Rockland County having a 60.34% vaccination rate, Orange County a 58.68% vaccination rate, Nassau County a 79.15% vaccination rate and Sullivan County a 62.33% vaccination rate.
The vaccination rate is higher in New York City — around 86%, according to an estimate previously reported by the city health department. Overall, children in New York state have a 78.96% polio vaccination rate.
According to a list kept by the Global Polio Initiative, 33 other countries have cVDPV — including 27 in Africa. The U.S. — which has not reported a case of wild polio since 1979 — is now the only country in the Americas with cVDPV.
Positive wastewater samples mean that either recently vaccinated people are shedding the virus or there are unreported asymptomatic cases in the community.
In addition to the slim possibility of contracting polio from the oral vaccine, everybody who takes it sheds it.
“People could have gotten the oral polio vaccine, and they’re shedding it in their stool. It’s still used in other countries because it’s easier and cheaper,” Glatt said.
New York officials said wastewater testing is ongoing, although the CDC noted that no additional cases of polio have been reported in New York or other parts of the U.S. and that the agency’s vaccination advice remains the same.
“On polio, we simply cannot roll the dice,” Bassett said last week. “If you or your child are unvaccinated or not up to date with vaccinations, the risk of paralytic disease is real. I urge New Yorkers not to accept any risk at all.”
References:
- Global Polio Eradication Initiative. Outbreak countries. https://polioeradication.org/where-we-work/polio-outbreak-countries/. Accessed Sept. 14, 2022.
- NYSDOH and NYCDOHMH wastewater monitoring identifies polio in New York City and urge unvaccinated New Yorkers to get vaccinated now. https://www1.nyc.gov/site/doh/about/press/pr2022/nysdoh-and-nycdohm-wastewater-monitoring-finds-polio-urge-to-get-vaccinated.page. Published Aug. 12, 2022. Accessed Sept. 13, 2022.
- Protecting New Yorkers through immunization: State department of health updates New Yorkers on polio in New York State. https://www.health.ny.gov/press/releases/2022/2022-09-09_polio_immunization.htm. Published Sept. 9, 2022. Accessed Sept. 13, 2022.
- New York State Department of Health. Wastewater surveillance. https://www.health.ny.gov/diseases/communicable/polio/wastewater.htm. Accessed Sept. 13, 2022.
- United States confirmed as country with circulating vaccine-derived poliovirus. https://www.cdc.gov/media/releases/2022/s0913-polio.html. Published Sept. 13, 2022. Accessed Sept. 13, 2022.
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