When the New York State Department of Health announced that a patient in Rockland County, north of New York City, had contracted polio, it revealed that it was a case of vaccine-derived polio.
Vaccine-derived poliovirus is different from poliovirus that originated in nature and spreads naturally within a community.
The NYSDOH said in a statement that tests, conducted by the department’s public health laboratory and confirmed by the Centers for Disease Control and Prevention, showed the patient was infected with type 2 Sabin poliovirus, which indicating that you were infected by someone who received the oral polio vaccine, which is no longer used in the United States.
Here’s what you should know about vaccine-derived polio and how it differs from wild polio.
Poliomyelitis, short for poliomyelitis, is highly contagious and spreads through person-to-person contact, even when the original contagious patient shows no symptoms.
According to the CDC, about one in four people have flu-like symptoms, such as fever, fatigue, and headache, that go away within a week. But in rare cases, polio can lead to paralysis and death.
People can protect themselves against polio with two types of vaccines: an inactivated poliovirus vaccine given by injection and an oral polio vaccine that contains a weakened version of the virus and is given by mouth.
The oral polio vaccine played a critical role in polio eradication because it is cheaper and easier to administer than the injected vaccine, making it suitable for distribution, especially in low- and middle-income countries.
“It’s a live, attenuated virus,” said Dr. John Brownstein, an epidemiologist at Boston Children’s Hospital and an ABC News contributor. “It’s a weakened virus that provides very good immunity in the gut, where the virus replicates, and is shed in faeces, which can spread through sewage and help protect the community.”
However, one possible adverse effect of the oral vaccine is vaccine-derived poliovirus.
In rare cases, the virus that spreads through sewage can affect those who are not vaccinated. This is different from wild polio, which infects people by circulating naturally in the environment.
Because of this risk, the oral vaccine was discontinued in the US in 2000. New York health officials said the virus in the Rockland County patient likely originated in a country outside the US. , where the oral vaccine is still administered.
The NYSDOH said Friday that only 61% of Rockland County residents have been vaccinated against polio before the age of 2, compared to a rate of 79% statewide, not including New York City.
“There is likely to be community transmission, and in an undervaccinated community like New York, it creates a susceptibility,” Brownstein said. “But in those who are vaccinated, there really is no risk.”
The New York case is not the first time vaccine-derived polio has been detected in the US.
In 2005, it was found in the feces of an unvaccinated, immunocompromised Minnesota child, and likely caught it from someone who received the oral vaccine in another country, according to the CDC. Later, seven other children contracted polio, but none ended up paralyzed.
In 2013, a severely immunocompromised infant received the oral vaccine in India. The baby ended up contracting polio and dying from the infection, the CDC said.