What you need to know about polio, vaccines in the U.S.

Adults who doubt they have been fully vaccinated against polio should talk to their doctors about getting additional shots, experts say.

A confirmed case of polio in New York state has renewed a sense of urgency to make sure everyone is fully vaccinated against the potentially fatal virus, said Duke infectious disease expert Dr. Cameron Wolfe.

“We never really worried about that because so many people had been vaccinated effectively that the disease was gone from the U.S. for decades,” Wolfe said. “Until now.”

The New York case, in which an unvaccinated man developed polio-related paralysis, is the first time since 1979 that a polio case originated in the U.S.

The oral polio vaccine (which some might remember as a sugar cube in a paper cup) was replaced in the U.S. with a series of shots in 2000 because of its ability in rare situations to reactivate itself into a form that was infectious.

Researchers at the Centers for Disease Control and Prevention found that the New York man was infected with a weakened version of the virus that comes from the oral vaccine, which is still used in some countries.

Subsequent wastewater testing in New York found that polio has been circulating locally for up to a year, according to the CDC, which points to many more asymptomatic infections.

“This one single case in New York has shown it can be the canary in the coal mine,” Wolfe said.

New York is not the only place with a recent resurgence in polio. A handful of polio cases in Europe are also raising red flags for global health researchers.

Most people with polio do not feel sick or have minor symptoms, like a fever, headache or limb pain. In rare cases, polio can cause irreversible paralysis.

According to the CDC, adults who know they are unvaccinated or who do not have documentation of their vaccination could qualify for three doses spread across several months.

Wolfe said it is unlikely for someone to be unvaccinated without knowing it unless they grew up outside of the United States. “It’s almost been like the foundational vaccine for so many years that it would be an unusual situation for someone not to have it,” he said.

Those who have only partially completed the three-dose series can go to a doctor to have their missing shots. Two doses of the vaccine are about 90% effective at preventing paralysis, while the full series is more than 99% effective.

Adults who have been fully vaccinated but are at high risk of exposure — health care workers who care for polio patients, or people traveling to countries like Afghanistan, where polio is still endemic — could qualify for a one-time booster shot.