How do we know vaccines are safe?

How do we know vaccines are safe?
Only vaccines that are proven to be safe, effective, and of high quality are approved for use in Canada. 
Here are some important things to know about vaccine safety:
  • The approval process for vaccines 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 for use by Health Canada. Occasionally, the process can be expedited (happen more quickly) if there is an urgent need for a vaccine (for example, during a pandemic). No safety steps are skipped in these cases, and the vaccine still has to meet all the same safety requirements. An example is COVID-19 vaccines
  • Health Canada only approves a vaccine if it is safe, it works, it 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 very rare event that a lot (batch) of vaccine results in an unexpected side effect, these systems can ensure that the rest of the lot is not used. 
Date last reviewed: 
Thursday, May 05, 2022