A smaller subgroup of people who get polio (less than one in 100, according to the CDC) develop symptoms that affect the brain and spinal cord. Some of those people may experience a tingling sensation in the legs, often described as pricklings of pins and needles. Others, regarding one in 25 people, may develop meningitis, which is inflammation of the membranes that cover the brain, spinal cord, or both.
The CDC estimates that one in 200 people with polio experience paralysis or weakness in the arms, legs, or both. The paralysis usually occurs on one side of the body, said Gail Shust, a pediatric infectious disease specialist at NYU Langone Health. In rare cases, polio-related paralysis can be fatal because the virus affects the muscles that help you breathe.
Even following someone recovers from polio, they can develop muscle aches, weakness, or paralysis 15 to 40 years later. Children recovering from polio can experience post-polio syndrome as adults, with muscle weakness, fatigue, and joint pain decades following initial infection. It is not clear why only some 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 into contact with the stool of an infected person and then touches their mouth. This is particularly concerning for children under the age of 5, who, according to Esper, may have difficulty with hand hygiene. “Any adult who has children knows that this is how germs are spread,” she said. Less commonly, polio can be spread when droplets from an infected person’s sneeze or cough enter someone’s mouth.
And just like COVID-19, it’s possible to spread the virus even if someone doesn’t have symptoms.
The oral polio vaccine, which helped eliminate the disease in the United States and is no longer administered in the country, contains weakened live poliovirus. It is safe and effective, but in very rare cases, the weakened virus in the vaccine can cause paralysis in other people. This is primarily a concern for unvaccinated people, to whom the vaccine-derived virus may be spread, and for people who are immunocompromised, who may not develop immunity from the vaccine. In exceptionally rare cases — regarding one in every 2.4 million doses of the oral vaccine — the weakened live virus can cause paralysis in the person who received the vaccine, said Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia. But the main concern is that the vaccine virus might circulate and spread in underimmunized communities.
Health officials in New York confirmed that the Rockland County person was exposed to someone who received the oral polio vaccine, which mutated to a pathogenic form of the virus. The person from Rockland was not vaccinated, making her vulnerable to getting polio.