Am I Protected Against Polio? Here’s What to Know About the Vaccine

If you got vaccinated between the early 1960s and 2000, you would have gotten the OPV, or oral poliovirus vaccine, administered in a little paper cup, on a sugar cube or by drops in your mouth. If you are younger than 22, you would have gotten the Inactivated Poliovirus Vaccine, or IPV, four doses administered in shots in the arm or leg.

If you are unsure about your status, you might need to do some sleuthing. Check with previous family doctors, high-school and college health departments, or consult childhood documents such as baby books or camp or school forms. You might also be able to check with your state’s health department. Some states have registries or immunization information systems that include adults’ vaccination records.

The poliovirus can cause flulike symptoms, such as fever and nausea, as well as more serious cases that affect the brain and spinal cord. Here’s what doctors and health officials say you need to know about protecting yourself and your family

Are my children protected against polio? What’s the polio vaccine schedule?

Most children in the U.S. have been vaccinated against polio as part of routine childhood immunizations. Children now normally get a dose of the polio vaccine when they are 2 months old, 4 months old and then between 6 months and 18 months. Children should get a fourth dose when they are 4 to 6 years old. Nationally, 94% of kindergartners are fully vaccinated, according to the CDC.

If you don’t have immunization records and aren’t sure whether your child is fully vaccinated, consult your pediatrician, your child’s school or their college. You might also be able to get a copy of your child’s vaccination record through your state’s health department or immunization registry.

How old is the polio vaccine?

The vaccine has changed several times over the years. The first effective vaccine, introduced in the U.S. in the 1950s and administered as a shot, was supplanted in the 1960s by oral vaccines that contained weakened live poliovirus. That gave way in 2000 to an injectable vaccine that doesn’t contain the live virus, to eliminate cases of the virus inadvertently transmitted by exposure to the feces of a person vaccinated with the live virus. Oral vaccines containing the live virus are still used in some countries.

How effective are the vaccines? Does the polio vaccine last a lifetime?

The IPV protects against severe disease caused by poliovirus in 99% of those who have received three of the four recommended shots and 90% of those who have gotten two shots, according to the CDC.  

The fourth dose of the vaccine given to children between the ages of 4 and 6 is a booster designed to maintain their long-term immunity to polio, according to the American Academy of Pediatrics. 

A study published in the journal BMC Public Health in 2016 found antibodies in 83% to 97% of more than 4,000 U.S. study subjects who were between the ages of 6 and 49. The variation depended on the type of vaccine they had received. Antibodies were found in 86% to 96% of the oldest study subjects, those ages 40 to 49, indicating that protective antibodies last for decades.  

Do adults need a booster for the polio vaccine?

For most people, childhood inoculations should provide sufficient protection. The CDC recommends an extra booster shot for people who are at increased risk of being exposed to the virus, such as lab and healthcare workers who might come into contact with polio patients or contaminated specimens, and travelers planning trips to high-risk areas abroad. 

A spokeswoman for the CDC says the agency will continue to monitor the situation and provide timely updates if the risk to the general public changes.

Widespread additional booster shots aren’t necessary because of the nature of the virus and population immunity, says Jesse Hackell, chairman of the American Academy of Pediatrics committee on practice and ambulatory medicine. 

“The poliovirus isn’t like Covid-19. It doesn’t mutate rapidly. It is relatively stable. It’s not likely we will see many infections in vaccinated people,” he says. 

Do my children need to get revaccinated?

You don’t need to worry about revaccinating your kids if you’re sure they have been fully vaccinated. However, if you’re not certain and can’t find your child’s vaccination records, your child should be considered susceptible to the disease and get vaccinated or revaccinated, according to the CDC. Children who haven’t started their polio vaccines or who have gotten behind on their shots should start or catch up as soon as possible, health officials say.

Do I need to be revaccinated?

If you aren’t sure whether you’ve been vaccinated, the CDC says to act as if you weren’t. Unvaccinated adults should get three doses of IPV—the first dose at any time, a second dose two months later and a third dose six to 12 months after that. Adults who have had only one or two doses of the vaccine may not be sufficiently protected and should get the remaining one or two doses. 

Write to Betsy Morris at betsy.morris@wsj.com