Polio Vaccine: What You Need to Know

The polio vaccine is the safest and most effective way to prevent polio, a dangerous and contagious viral infection that attacks the nervous system. Before the vaccine, polio outbreaks caused lifelong paralysis in thousands of people in the United States.

Read on to learn more about the polio vaccine and how it works.

What Is the Polio Vaccine?

The polio vaccine is the primary means for preventing polio. The only type available in the United States is the inactivated poliovirus vaccine (IPV), which contains killed versions of the poliovirus. The vaccine teaches a person’s immune system to recognize and attack the living poliovirus should there be an exposure in the future.

There is a second type of polio vaccine: the oral polio vaccine (OPV), used in some parts of the world, which uses living but weakened viruses.

Because there is no cure for polio, preventing the disease is even more important.

Polio can lead to severe complications, including paralysis, difficulty breathing, and in some cases, death. Though most cases of polio are asymptomatic (don’t have visible symptoms), about 1 in 200 infections can cause irreversible paralysis. Of those paralyzed, 5 to 10 percent die when their breathing muscles become immobilized (cannot move or otherwise function).

Meningitis (infection of the covering of the spinal cord or the brain) occurs in about 1 to 5 percent of people with polio.

The polio vaccine has eliminated polio in most of the world. Of the three variations of poliovirus that ever existed, two are now eradicated, while the remaining one (known as wild poliovirus type 1 or WPV1) — the type most likely to cause paralysis — is present only in some parts of the world.

Since the vaccine was introduced, cases due to WPV1 have decreased by over 99 percent, from an estimated 350,000 cases in more than 125 endemic countries to just two endemic countries, Afghanistan and Pakistan. An endemic country is where a disease is consistently present, typically year-round.

Even though the poliovirus has been eliminated from the United States, it only takes a single traveler with the virus arriving from another country to increase the threat level.

In 2022, one person in the New York area developed polio that resulted in paralysis, and the virus was found in wastewater in the adjoining and nearby counties, indicating that it had spread in the community. Fortunately, the outbreak ended without further harm.

Polio spreads via coughing and sneezing or from coming into contact with the feces of an infected person. Drinking contaminated water, eating foods that have touched contaminated water, and touching contaminated surfaces can also lead to transmission.

The poliovirus infects the throat and the intestines and causes flu-like symptoms before possibly spreading to the nervous system and resulting in paralysis.

All children in the United States may receive four doses of the polio vaccine as part of their routine childhood immunizations. Adults who received childhood vaccines in the United States almost certainly were vaccinated for polio.

However, the 2022 case of polio in New York underscored potential risks for unprotected adults in the United States. In 2023, the Centers for Disease Control and Prevention (CDC) began recommending that all adults (18 years and older) who are known or suspected to be unvaccinated or incompletely vaccinated against polio complete a primary three-dose vaccination series.

The series is given at an interval of four to eight weeks; and a third dose 6 to 12 months after the second.

Adults who are not fully immunized should aim to complete the primary series of the polio vaccine if they plan to travel internationally. Some countries may require those who are departing to provide proof of polio vaccination on the yellow International Certificate of Vaccination or Prophylaxis (ICVP).

If adults can’t complete the recommended series schedule before traveling, the CDC recommends an accelerated schedule (three doses administered at least four weeks apart).

While the polio vaccine is safe for nearly everyone, some people shouldn’t get the vaccine. Reasons not to get the polio vaccine include:

Severe Allergic Reactions Individuals who have had severe allergic (anaphylactic) reactions after a previous vaccine dose or after taking streptomycin, polymyxin B, or neomycin should not receive the shot.

The polio shot contains trace amounts of streptomycin, polymyxin B, and neomycin, and people who are sensitive to these antibiotics can also have hypersensitivity reactions to vaccination.

Pregnancy Although there is no evidence that the polio vaccine causes harm to pregnant individuals or their fetuses, it shouldn’t be given during pregnancy if there is not an increased risk of infection.

However, a pregnant woman who is at increased risk for exposure and requires immediate protection against polio should receive the vaccine in accordance with the recommended schedules for adults, per the CDC.

As part of the routine vaccines recommended for all babies and children, children should get a polio vaccine dose at the following ages:

2 months
4 months
6 to 18 months
Between 4 and 6 years

For adults or older children who have missed doses or are unvaccinated, the primary series consists of three doses: two doses separated by four to eight weeks, with a third dose given 6 to 12 months after the second.

Two doses of inactivated polio vaccine are 90 percent effective or more against paralytic polio, and three doses are 99 to 100 percent effective.

It is not known how long people who received the polio vaccine in injected form in the United States will be protected, but they are most likely protected for many years after a complete series.

A 2009–2010 national survey showed that a high percentage of children and adults had protective antibodies against poliovirus, including adults who had received oral polio vaccine (OPV) as children decades earlier.

Adults who completed their polio vaccination series as children and are at high risk may need a booster and should consult their healthcare provider. Situations that increase risk include traveling to areas with ongoing polio outbreaks or working in healthcare settings.

Serious side effects of the polio vaccine are rare, and the benefits far outweigh any potential risks. Polio can lead to permanent paralysis and even death. The vaccine risks are mild side effects that go away within a day or two.

Vaccines don’t always go through placebo-controlled trials, but they do go through rigorous safety testing. In some cases, it isn't ethical to hold placebo-controlled trials (in which some people who think they are receiving a vaccine are getting a fake), such as when a vaccine has already been shown to prevent disease and death.

Is the Polio Vaccine Linked With Cancer?

A portion of Americans who got the polio vaccine between 1955 and 1963 received doses that were contaminated with SV40, a carcinogenic material. The virus causes cancer in rodents, but it has not been shown to cause cancer in humans.

There isn’t evidence that people who were vaccinated during this period have developed cancer at a higher rate than those who were not.

Most people experience no side effects from the polio vaccine, but some may have mild reactions, such as redness or swelling at the injection site. These side effects usually go away within a few days. Severe reactions, like allergic responses, are extremely rare.

The cost of the polio vaccine is typically covered by insurance. Vaccination through public health programs is often low cost or free. Out-of-pocket cost for a single dose of the vaccine may cost between $70 and $85.

Your child’s healthcare provider or your local health department are the best places to get recommended childhood vaccines. Vaccines may also be available at your local pharmacy. Visit the CDC’s vaccine-finder tool for more information on where to get the vaccine.

The polio vaccine is safe and highly effective in preventing the spread of polio, a disease that can cause paralysis and death.
All children in the United States should receive the polio vaccine as part of their routine immunizations, with four doses given between 2 months and 6 years old.
Adults who are unvaccinated or incompletely vaccinated should get the full primary vaccine series, especially if they are traveling to areas where polio is still a threat.

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What Is the Polio Vaccine?

Is the Polio Vaccine Linked With Cancer?