Fact Sheet about Polio

What is Polio?

Polio (short for “poliomyelitis”) is a very contagious disease caused by a virus. It is rare in the U.S. Approximately 95% of people infected with polio will have no symptoms. About 4 – 8% of those infected will have minor symptoms such as fever, fatigue, nausea, headache, flu-like symptoms, stiffness in the neck and back, and pain in the limbs, which often resolve completely. Fewer than 1% of polio cases result in permanent paralysis of the limbs (usually the legs).

Polio may not cause serious illness in most people, but sometimes it can kill people who get it, usually by paralyzing the muscles that help in breathing. Polio is still common in some parts of the world. So, although there hasn’t been a case of polio caused by naturally occurring virus in the United States since 1979, there is still a risk of the virus coming into this country.

Is polio dangerous?

Yes. Before polio vaccines were developed, thousands of people a year in the United States were paralyzed and killed by the disease. Polio vaccine is helping to rid the world of polio. When that happens, no one will ever get polio again, and we will not need polio vaccine.

How is polio spread?

The virus that causes polio is spread from the throat and through stool (feces). People can also spread the virus by touch if they do not wash their hands after coughing or using the toilet. Food and liquids can be contaminated this way. People who have not been immunized can get polio disease by eating food or drinking liquids containing the virus. People with polio may spread the disease from about 1 week before their symptoms start until about 6 weeks after. Symptoms usually start about one to three weeks after a person is exposed.

How can you prevent polio?


Protect your children by having them vaccinated when they are 2 months, 4 months and 6 - 18 months old, and again when they are about to enter kindergarten. State regulations require children attending childcare/preschool, and those in kindergarten through grade 12 to be vaccinated against polio.


Most adults do not need polio vaccine because they were already vaccinated as children. But three groups of adults are at higher risk and should consider polio vaccination:

  • People traveling to areas of the world where polio is occuring
  • Laboratory workers who might handle poliovirus
  • Healthcare workers treating patients who could have polio

How many polio vaccines are there?

Currently only inactivated polio vaccine (IPV), which is a shot, is available in the United States. Oral polio vaccine (OPV), which is contained in drops that are swallowed, is no longer distributed in the US.

Are polio vaccines safe?

IPV is very safe. However, as with any medicine, vaccines can cause side effects in some people. A few people who get IPV get mild soreness where the shot was given. There is a very small risk of more severe side effects and allergic reactions (hives, difficulty in breathing, shock) but they are very rare. The risk of a polio shot causing serious harm or death is extremely small. The polio shot (IPV) has been used since 2000 in the United States. It does not cause polio.

OPV used to be recommended in the United States. This stopped in 1999. OPV helped rid the country of polio, and it is still used in many parts of the world. Both OPV and IPV give immunity to polio; however, for a few people (about one in 2.4 million), OPV actually causes polio. Since the risk of getting polio in the United States is now extremely low, experts believe using OPV is not worth the slight risk.

Who should not get IPV?

  • Anyone who is allergic to any of the following antibiotics: neomycin, streptomycin or polymyxin B, because small amounts of these may be in the vaccine.
  • Anyone who has had a severe allergic reaction to polio shot.

Should travelers get polio boosters before leaving the United States?

Travelers should check their records to make sure they are up-to-date on all vaccines when planning to leave the United States. Polio no longer occurs in the Western Hemisphere, Europe, USA, Japan, China, South East Asia, Australia, New Zealand and other countries in the Western Pacific region. Children should be up-to-date for their age on all vaccines before traveling. Adults who are not completely vaccinated should get as many doses as possible before departure. Adults who have had 3 doses might need another dose before traveling to areas where polio still occurs, including developing countries in Africa, South Asia and some parts of the Middle East.

To find out if the CDC recommends a polio booster dose for a trip, call 1-877-394-8747 or visit either the CDC Travel Information website or the World Health Organization Polio Eradication website.

What is post-polio syndrome?

Post-polio syndrome tends to strike people 20 to 30 years after they first had the disease. (This syndrome is also called post-polio muscle atrophy or late effects of polio.) Symptoms include muscle weakness, cramps and pain, increased fatigue, and trouble breathing. Up to one in four polio survivors may suffer from this syndrome.

Where can I get more information?

  • Your doctor, nurse or clinic, or your local board of health (listed in the phone book under local government).
  • The Massachusetts Department of Public Health, Immunization Program (617) 983-6800 or toll-free at (888) 658-2850, or on the MDPH website.
  • Boston providers and residents may also call the Boston Public Health Commission at (617) 534-5611.
  • CDC National Immunization Information Hotline:
    • English: (800) 232-2522 (Mon – Fri, 8am – 11pm)
    • Spanish: (800) 232-0233 (Mon – Fri, 8am – 11pm)
    • TTY: (800) 243-7889 (Mon – Fri, 10am – 10pm)

Spanish and Portuguese translations of this fact sheet are available under additional resources.

Additional Resources

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