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How do we know vaccines are safe?

How do we know vaccines are safe?
Only vaccines that are proven safe, effective, and of high quality are approved for use in Canada. 
Here are some important things to know about vaccine safety:
  • The vaccine approval process is more stringent than most drugs available in Canada.
  • It can take up to ten years or longer for a vaccine to be developed, tested, and approved by Health Canada. Occasionally, the process can be expedited (happen more quickly) if a vaccine is urgently needed (for example, during a pandemic). No safety steps are skipped in these cases, and the vaccine must meet all the same safety requirements. An example is COVID-19 vaccines. 
  • Health Canada only approves a vaccine if it is safe, works, meets manufacturing standards, and the benefits outweigh the risks.
  • Because vaccines are given to healthy people, including children, they are held to the highest safety standard—even higher than most drugs used for treatment. 
  • Like any medicine or supplement (including vitamins), vaccines can cause side effects. Usually vaccine side effects are minor, such as a sore arm or mild fever, and go away quickly. Many people who receive vaccines have no side effects at all. Serious side effects are very rare. 
  • A vaccine’s safety is continuously monitored following its approval. 
  • Canada has several advanced systems in place (at the local, provincial, and national levels) to carefully monitor the safety of vaccines and detect any safety concerns. 
  • In the rare event that a lot (batch) of vaccines result in an unexpected side effect, these systems can ensure that the rest is not used.

Learn about how vaccines are tested, approved, and monitored

Learn about vaccine side effects


Date last reviewed: 
Thursday, May 05, 2022