Vaccine Safety

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Vaccines, like all medicines, are put through a lot of testing before they are approved for use in Canada. Vaccines are held to the highest possible safety standard in healthcare. It often takes 10 or more years of studying and testing before a vaccine is approved. See the following links for more information:

Vaccine Safety in Canada

Vaccine Safety is Important to All of Us:  Information for Parents

Canadian Center for Vaccinology

Canadian Immunization Guide

Immunize Canada

Parents for Vaccines

Why I Vaccinate Video Series

Voices for Vaccine

Side Effects/Adverse Events Following Immunization (AEFI)

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An Adverse Event Following Immunization (AEFI) is any adverse medical event that happens after an immunization, no matter if the immunization caused it or not.

Common Adverse Events

Some of the most common side effects that happen after getting a vaccine are:

  • soreness, redness, and swelling at the place where the needle went in
  • low grade fever - this means your body is working hard to build immunity
  • tiredness and irritability (especially in small children)
  • headache

Ask your healthcare provider what to look for after getting a vaccine.

Less Common and Rare Adverse Events

A small number of people have more serious reactions to vaccines. If you notice something that you are worried about or that you think is serious, see a healthcare provider.

Allergic reactions like hives (blotchy, red, raised areas), wheezing, or swelling of the face and mouth are extremely rare. If you notice any of these symptoms, go to an emergency department immediately.

Serious reactions are very rare, but when they do occur, they must be reported to Public Health. When they are reported, reactions to a specific vaccine can be tracked. If the risks of a vaccine outweigh the benefits, it is pulled from the market.

Evaluating Risks

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When two things happen close together, it does not always mean that one caused the other. For example, if someone goes for a bike ride and then breaks a leg later that day, it does not necessarily mean that the bike ride caused the leg to break. The two events are linked because they happened close together (correlation), not because the bike ride caused the break (causation). The same goes for vaccines. Sometimes a person experiences something after getting a vaccine, but the vaccine may not have been the cause.

When making decisions about vaccines, it is important to think about risks vs. benefits. No medical intervention is 100% risk free, but the chances of having a serious reaction to a vaccine are very small. Learn more about evaluating risks when you make decisions about vaccines.

For more information contact