Interchangeable Vaccines Provide a Safe and Effective Second Dose

cjos covid

To ensure maximum protection against COVID-19, everyone should get vaccinated as soon as they can and book their second dose as soon as they are eligible.

Mixing vaccines is safe, effective, and ensures everyone can receive their second dose sooner. Full vaccination is the greatest protection against COVID-19 and its variants, including the Delta variant.

Data collated over past six months establishes the safety of interchangeable use of mRNA vaccines. If you had Moderna or Pfizer for your first dose you can safely take either Moderna or Pfizer for your second dose. Both Moderna and Pfizer vaccines are authorized for use in Canada and use a similar mRNA technology, so the vaccines are safe to mix.


If you had AstraZeneca for your first dose you can safely take either Moderna, Pfizer or AstraZeneca for your second dose for strong protection.

  • Getting a Moderna or Pfizer vaccine after the first dose of an AstraZeneca vaccine has been shown to provide a strong immune response, including against COVID-19 variants of concern.
  • Dose interval is 8-12 weeks, on consent.


If your second COVID-19 vaccine is different than your first dose, you do not need to start your series over again. You will be considered fully immunized two weeks after receiving two doses of Health Canada approved COVID-19 vaccines.


All COVID-19 vaccines approved for use in Canada are safe and effective and they all reduce the risk of serious illness, hospitalization, and death, and will help with the control of COVID-19 in the community.

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