Vaccine Safety


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

Side Effects/Adverse Events Following Immunization (AEFI)

Sometimes people respond to immunizations in unexpected ways. An Adverse Event Following Immunization (AEFI) is any adverse medical event that happens after an immunization, regardless of whether the immunization caused it or not. The most common side effects that happen after getting a vaccine are soreness, redness, and swelling at the place where the needle went in. Sometimes people develop a low grade fever – this means your body is doing its job and is responding to the vaccine. Some  people, particularly younger children, are more tired and irritable than usual; headaches can also happen.  Ask your healthcare provider what to look for after getting a vaccine.

A small number of people do have more serious reactions to vaccines. If you notice something that concerns you 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. Otherwise, see your healthcare provider. Your healthcare provider will assess you to see if this is related to the vaccine or if you have another underlying condition. 

Serious reactions are very rare, but when they do occur, it is important that they are reported to Public Health. When they are reported, the health care system can track how many people have reactions to a specific vaccine. The vaccine is pulled from the market if it is connected to serious reactions and the risks of the vaccine outweigh the benefits.

Just because something happens shortly after getting a vaccine is given does not necessarily mean it was caused by the vaccine. For example, if someone eats an apple and then loses a tooth later that day, that does not necessarily mean the apple caused the tooth to fall out. The two events are linked because they happened close together (correlation), but that does not mean that the apple was the cause of the tooth loss (causation).

When making decisions about vaccines, it is important to evaluate risks vs. benefits. Although no medical intervention is 100% risk free, 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