Polio (short for poliomyelitis) is a very serious, contagious disease that is caused by the poliovirus. The virus can attack an infected person’s nerve cells in the spinal cord. This can leave muscles permanently weak or damaged. About 1 in every 100 people infected with the virus becomes paralyzed (unable to move).

Thanks to immunization, Canada has been polio-free since 1994. But before the polio vaccine was introduced in 1955, thousands of Canadian children were affected. The disease still happens in other countries, so there is still a risk for Canadians. That’s why immunization in childhood is recommended.

Children under 5 years of age are at the highest risk of getting polio. However, any person — at any age — who is not immune to the poliovirus can become infected.

How polio is spread

Polio is very contagious. The virus lives in an infected person’s throat or intestines. It enters the body through the mouth, and spreads through contact with the feces (poop) of an infected person. It can also be spread in the air when an infected person coughs or sneezes. An infected person may spread the poliovirus to others right before and about 1 to 2 weeks after they have symptoms.

90% of people who get polio don’t have any symptoms. However, these people can still pass the poliovirus to others and make them sick.

Risks of polio

Polio can be very serious. It used to be called “the crippler,” because polio can permanently damage the nerves that control muscles. The effects of the disease can last for the rest of a person’s life.

Long-term effects of polio can include muscle weakness, severe pain and feeling very tired. Polio can even result in death if the muscles that control breathing are paralyzed. Among people who are paralyzed, 5% to 10% of them will die due to respiratory failure.

Even children who seem to recover from polio can develop new muscle pain, weakness or paralysis as adults, as many as 30 or 40 years later. This is known as post-polio syndrome.
Thanks to immunization, Canada has been free of polio for more than 25 years. Polio has also been eradicated in most other countries; however, it still happens in some parts of the world. Someone infected with polio could travel to Canada and infect people here who are not immunized.

As well, Canadians who are not immunized against polio can get it while they are visiting countries where the disease still exists. The people who are most at risk are those who never had the polio vaccine, those who never received all the recommended vaccine doses, and those who travel to areas that could put them at risk for getting polio.


Many people who are infected with polio don’t have any symptoms. Those who do have symptoms may experience:

  • sore throat
  • fever
  • feeling very tired
  • headache
  • stomach pain
  • nausea

In rare cases, people with polio infection may develop more serious symptoms that affect the brain and spinal cord. Paralysis is the most serious symptom of polio because it can lead to permanent disability or even death.

Protection and prevention

You can protect against polio with a safe and effective vaccine. In Ontario, children receive a total of 5 doses of polio vaccine. The vaccine is given at:

  • 2 months, 4 months, 6 months and 18 months of age
  • between 4 and 6 years of age

Vaccination is the best way to protect against polio. The vaccines are part of the publicly funded vaccine schedule and are offered free to all children in Ontario. The polio vaccine is required for children to attend school in Ontario and for children attending a daycare centre unless they have a valid exemption.

Anyone who is not protected is at risk of getting polio. Talk to your health care provider before you travel. Polio still exists in a number of countries around the world. For more information for travellers, please visit the Government of Canada website.

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