How worried should parents be about polio? Here’s what experts say.

Polio isn’t typically something most parents worry about — after all, there hasn’t been a case of polio originating in the U.S. since 1979 thanks to vaccines, according to the Centers for Disease Control and Prevention (CDC).

But after the polio virus was found in wastewater in New York recently, it’s understandable that some parents may be concerned or have questions, given that polio was once considered “one of the most feared diseases in the U.S.,” according to the CDC.

Here’s what parents need to know about polio and what they can do to protect their kids.

How is polio spread?

Polio is “shorthand for poliomyelitis, a disease of the central nervous system caused by infection with poliovirus,” Dr. Richard Lloyd, professor of molecular virology and microbiology at Baylor College of Medicine, tells Yahoo Life.

The highly-contagious and potentially life-threatening disease is most commonly spread person-to-person “via the fecal-oral route,” Dr. Ashley Lipps, an infectious diseases physician at the Ohio State University Wexner Medical Center, tells Yahoo Life, such as by “ingesting something” — such as water or food — “that has been contaminated by fecal matter from an infected person.”

The CDC notes that “if your child puts objects, like toys, that have stool or droplets on them into their mouth, they can get infected.” In addition, “Changing diapers of an infected child is a mode of transmission,” says Lloyd. Droplets from an infected person’s cough or sneeze can also spread the disease, according to the CDC.

How dangerous is polio?

Most cases of polio are asymptomatic, while about 1 out of every 4 people will experience flu-like symptoms, including sore throat, fever, fatigue, nausea, headache and stomach pain, which typically last for about two to five days, according to the CDC.

However, in some cases, the virus can cause “severe illness,” Dr. Pedro Piedra, professor of molecular virology and microbiology at Baylor College of Medicine, tells Yahoo Life — namely, when it affects the brain or spinal cord. “A small proportion of people with polio can have devastating neurologic complications including meningitis and paralysis,” says Lipps. “The paralysis can be permanent and lead to death.” That’s because, in severe cases, the virus affects the muscles that help people breathe.

There is also a condition called "post-polio syndrome" in which children who seem to fully recover from polio initially can develop neurologic complications, such as muscle weakness or paralysis and joint pain, years or even decades later, according to Lipps. More specifically, these symptoms can start 15 to 40 years after the initial infection, per the CDC. However, unlike polio itself, post-polio syndrome is not contagious.

Why is polio more common in children than adults?

Most cases of polio occur in children under 5 years old. “Historically, poliomyelitis is mostly a disease of children because children are unprotected, unvaccinated and more likely to become infected and then develop the serious disease,” explains Lloyd. “This is why the United States and WHO have had strong vaccination programs in babies for decades, and vaccination was required to go to school in the U.S.”

Polio can occur because of “poor hygiene practices,” says Lipps, as it is spread via contamination from fecal matter. “Infants and young children who are not potty trained can more easily facilitate transmission,” she says.

How is polio prevented?

Experts say that widespread use of the polio vaccine made all of the difference in terms of eliminating polio cases originating in the U.S. In the 1940s and 1950s, polio was “one of the most feared diseases,” says Lipps, “causing outbreaks that resulted in large numbers of people with permanent disability.” She points out that in the late 1940s, an estimated 35,000 people per year were disabled due to polio.

“We used to have outbreaks of polio until vaccines were implemented early during infancy,” says Piedra. “The National Foundation for Infantile Paralysis, which became the March of Dimes, was founded to combat polio, which led to the development of two effective vaccines.”

They are the inactivated polio vaccine (IPV) — an injection given in the leg or arm, depending on the age of the patient — and the oral polio vaccine, though IPV is the only polio vaccine given in the U.S. since 2000, according to the CDC. (The oral vaccine, administered as drops in the mouth, is still used in some other countries.)

“The first vaccine was developed in 1955 and shortly after that time, cases of polio dropped dramatically,” says Lipps. “Due to highly successful vaccination efforts, the last case of polio that originated in the United States was in 1979. However, polio still occurs in other countries and it is possible for travelers to bring polio into the country.”

Similar to COVID-19, “poliovirus can always be brought back to the U.S. or other countries by traveling individuals who are infected overseas,” says Lloyd. “This is what probably happened in the recent polio discovered in New York. Until the virus is eliminated worldwide, this risk will not vanish.”

How concerned should parents be about polio?

Parents who have vaccinated their children should not be concerned about their kids developing poliomyelitis, says Lloyd.

Cases of polio in the U.S. are “extremely rare,” notes Lipps. In fact, today “there is only a single known poliomyelitis case in the U.S.,” points out Lloyd. That’s largely due to the fact that “a very high percentage of Americans are vaccinated,” he says.

The polio vaccine is given as part of routine childhood immunizations. The series of four doses total starts at age 2 months, followed by one dose at age 4 months, another dose at 6 to 18 months, and then a booster at 4 to 6 years old. “Those who are at an increased risk for polio include those who have not completed the full vaccine series and people who travel internationally to areas where polio occurs more frequently,” notes Lipps.

What can parents do to protect their children?

There is no cure for polio, but it can be prevented with the polio vaccine. Lipps points out that the vaccine is highly effective — three doses are 99% to 100% effective against polio, per the CDC. "This is the most successful vaccine ever developed," says Lloyd. "Use it.”

Lipps agrees, saying: “Far and away the most important thing you can do to protect your children against polio is to make sure they are up-to-date on their vaccinations.”

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