Information on a Safe and Effective Second Dose

Published on June 22, 2021

As the government continues to accelerate second doses to provide maximum protection against COVID-19 variants, it’s important that all Ontarians book their second as soon as they are eligible to help protect against COVID-19 and its variants.


Mixing vaccines is safe, effective, and enables more Ontarians to receive their second dose sooner. Individuals who had Moderna or Pfizer for their first dose can safely take either for their second. Individuals who had AstraZeneca for their first dose can safely take AstraZeneca, Moderna or Pfizer for their second. Full vaccination is the greatest protection you can have against COVID-19 and its variants, including the Delta variant.


This is consistent with the clinical studies and practices of other jurisdictions. The National Advisory Committee on Immunization has also confirmed that a mixed vaccine schedule is safe and is effective at protecting individuals and their loved ones from COVID-19. All vaccines provide strong protection against COVID-19 and its variants, and the best vaccine for a person’s second dose is the first vaccine that is available.


To help provide further clarity on this to Ontarians, we have developed a fact sheet on a safe and effective second dose:


The best vaccine for your second dose is the vaccine that is available first.


Learn more about getting your second dose: