In the early 1900s, up to 35,000 Americans a year were disabled by polio. The virus, which mainly spread during summer months, was finally tamed with a highly effective and widely embraced vaccine.
For decades, transmission had disappeared in the United States. Until now.
New York reported a confirmed case of paralytic polio in July, and wastewater surveillance showed the virus may have been circulating in neighboring counties since April.
Health experts are calling it a “wake-up call,” but they don’t think the single case or subsequent viral detection will lead to a countrywide outbreak akin to COVID-19 or monkeypox, as over 90% of the country’s young children are vaccinated against polio.
Experts, however, say pockets of unvaccinated people across the country may be at risk.
“What worries me is the communities where vaccination is suboptimal,” said Dr. Wafaa El-Sadr, professor of epidemiology and medicine at Columbia University Mailman School of Public Health. “It is in those communities where you’re likely to get spread rather than communities with coverage.”
Health officials announced on July 21 that a young adult in Rockland County, New York, had been diagnosed with polio in June. The person had never been vaccinated against the virus, officials said, and suffered paralysis as a result of the disease.
A report from the Centers for Disease Control and Prevention shows the case – the first transmitted within the U.S. since 1979 – came from a person who had taken an oral polio vaccine in a different country. A rare complication of the attenuated live vaccine, which has not been given in the U.S. in more than two decades, allowed the person to develop a mild case of polio and shed the disease.
Like every state in the U.S., New York requires children to get a polio vaccination before attending child care facilities and schools.
But in Rockland County, only about 60% of children under 2 received their recommended series of the polio vaccine, according to state data. The CDC report showed some zip codes have vaccination coverage as low as 37%.
“Ideally, you want more than 90% at minimum among children,” El-Sadr said.
Although data is inconsistent throughout the country, health experts say low vaccination rates aren’t unique to New York. There are likely other states with pockets of unvaccinated residents who could be vulnerable to the virus.
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Meanwhile, wastewater surveillance showed the polio virus in 21 sewage samples taken in Orange and Rockland counties since April, the CDC reported.
“For every one case of paralytic polio identified, hundreds more may be undetected,” New York health commissioner Dr. Mary T. Bassett said in a statement. “The detection of poliovirus in wastewater samples in New York City is alarming, but not surprising.”
Low levels of vaccination and circulating virus in wastewater indicate “a very major storm developing” in these communities, said Dr. Luis Ostrosky, an infectious disease specialist at University of Texas Health Science Center at Houston and Memorial Hermann Hospital.
The “wastewater is showing us there are infected people in the community that aren’t showing clinical signs and symptoms,” he said, as only about 1 in 2,000 people who are infected with the poliovirus develop the disease.
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The best way to prevent further transmission in vulnerable communities is through vaccination, health experts say. The standard vaccination series for polio consists of four doses: one at 2 months old, the second at 4 months, the third between 6 and 18 months, and the fourth between 4 and 6 years old.
Officials urge parents to make sure their children are current with their vaccines. An April report from the CDC found coverage among kindergartners for the 2020-2021 school year fell by 1% due to disruptions from the COVID-19 pandemic.
“We really have to play catch up for some children,” El-Sadr said. Health care providers must “remind parents of the importance of getting their kids vaccinated as soon as possible.”
The highly infectious disease is spread through contact with infected feces, often when children don't wash their hands correctly, health experts said. So, it's also important to maintain good hand hygiene.
The single case of polio likely won't result in a nationwide outbreak, but it's a reminder that even eliminated diseases can reappear if the public isn't careful, said Dr. Daniel Pastula, a neuro-infectious disease expert at the University of Colorado Anschutz Medical Campus.
“Poliovirus isn’t eradicated around the world," he said. “Under the right conditions, it can rear its ugly head and those conditions are lack of vaccinations, contaminated water and food and unrobust public health systems.”
Contributing: Chris McKenna and Nancy Cutler, USA TODAY NETWORK. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.
Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.
This article originally appeared on USA TODAY: Polio NYC: Rockland County case won't spread like COVID, experts say