Canada has one of the most thorough systems to approve new vaccines for use in people.
Last updated: January 18, 2021
During vaccine development, vaccines are first tested in animals before being studied in humans. Testing in humans is done over three phases of clinical trials. These trials provide crucial information on vaccine safety as well as effectiveness.
- Usually involves up to 100 healthy adults
- Assesses whether there are any initial safety concerns
- Assesses whether the vaccine creates the right immune response
- Usually involves up to 500 participants
- Assesses safety concerns
- Determines the amount of vaccine that creates the right immune response.
- Usually involves anywhere from thousands to tens of thousands of people
- Assesses the safety of the vaccine
- Assesses the ability of the vaccine to prevent the disease
Once vaccine manufacturers have successfully completed all three phases, they must submit the data to Health Canada. They have a regulatory authority responsible for approving vaccines for human use.
The regulatory authority ensures that the laboratory and clinical studies:
- provide evidence of product safety,
- that the manufacturing process meets a high standard, and
- that the product meets the highest standards of quality.
The COVID-19 vaccines completing Phase 3 clinical trials have been tested in a range of people. This includes:
- adults from a range of ages including older adults,
- those with stable underlying chronic diseases, and
- a range of ethnicities.
Vaccines are tested in adults before being tested in children. The current COVID-19 vaccines have been tested and approved for use in adults, for whom COVID-19 is a more serious illness.
Initial safety information from the two mRNA vaccines suggests people experience mild to moderate fatigue, pain and in some cases chills, headache or joint pain after immunization. These are normal vaccine side effects (and are often usual side effects of influenza vaccination).