The CDC estimates that one in 200 people with polio experience paralysis or weakness in the arms, legs, or both. Paralysis usually occurs on one side of the body, said Dr. Gail Shust, pediatric infection specialist at NYU Langone Health. In rare cases, polio-related paralysis can be fatal, as the virus can affect the muscles that support breathing.
Even after a person has recovered from polio, they may develop muscle pain, weakness, or paralysis 15 to 40 years later. Children recovering from polio may develop post-polio syndrome in adulthood, with muscle weakness, fatigue, and joint pain within decades of their initial infection. It’s not clear why only a few people develop post-polio syndrome, but those who have experienced severe cases of polio may be more susceptible.
How is polio spread?
Polio is very contagious. It spreads from person to person – usually when someone comes in contact with an infected person’s stool and then touches their mouth. This is particularly worrisome for children under the age of 5, who, said Dr. Esper, may have trouble with hand hygiene. “Any adult who has children knows that germs are spread like that,” he said. Less commonly, polio can be spread when droplets from an infected person who sneezes or coughs enter a person’s mouth.
And as with Covid-19, it is possible to spread the virus even if you have no symptoms.
The oral polio vaccine, which has helped the United States eradicate polio and is no longer administered in the country, contains attenuated live polio virus. It’s safe and effective, but in very rare cases, the weakened virus from the vaccine can revert to a form that can cause paralysis in other people. This is primarily a concern for unvaccinated people, to whom the vaccine-derived virus can spread, and immunocompromised people, who may not have developed immunity to the vaccine. In exceptionally rare cases — about one in every 2.4 million doses of the oral vaccine — the attenuated live virus can cause paralysis in the person who received the vaccine, said Dr. Paul Offit, a vaccine expert at Children’s Hospital in Philadelphia. But the biggest concern is that the vaccine virus can circulate and spread through under-immunized communities.
Health officials in New York confirmed that the person in Rockland County had been exposed to someone who received the oral polio vaccine, which mutated to a pathogenic form of the virus. The person in Rockland County had not been vaccinated, leaving them vulnerable to polio.
The oral polio vaccine has not been administered in the United States since 2000. Today, in the United States, the polio vaccine is a highly effective injection, containing no live virus, unlike the oral vaccine.