An unvaccinated adult from New York recently contracted polio, the first case in the United States in nearly a decade, health officials said Thursday.
Officials said the person, living in Rockland County, had developed paralysis. She began having symptoms a month ago and has not recently traveled outside the country, county health officials said.
It appears the person had a vaccine-derived strain of the virus, possibly from someone who received a live vaccine — available in other countries, but not in the United States — and spread it, officials said.
The person is no longer considered contagious, but investigators are trying to figure out how the infection happened and if other people may have been exposed to the virus.
Most Americans are vaccinated against polio, but unvaccinated people may be at risk, said Rockland County Health Commissioner Dr. Patricia Schnabel Ruppert. Health officials held nearby vaccination clinics on Friday and Monday and encouraged anyone who was not vaccinated to get an injection.
“We want injections in the arms of those who need it,” she said at a press conference Thursday announcing the case.
Polio was once one of the country’s most feared diseases, with annual outbreaks causing thousands of cases of paralysis, many of them in children.
Vaccines became available from 1955, and a national vaccination campaign reduced the annual number of cases in the United States to less than 100 in the 1960s and less than 10 in the 1970s, according to the Centers for Disease Control. diseases (CDC).
In 1979, poliomyelitis was declared eliminated in the United States, meaning there was no longer any systematic spread.
There are two types of polio vaccines. The United States and many other countries use injections made with an inactivated version of the virus. But some countries where polio has been a more recent threat use a weakened live virus that is given to children as drops in the mouth. In rare cases, the weakened virus can mutate into a form capable of triggering new outbreaks.
American children are still routinely vaccinated against poliomyelitis with the inactivated vaccine.
According to the CDC’s most recent childhood immunization data, about 93 percent of 2-year-olds had received at least three doses of polio vaccine.