How do we know that mixing COVID-19 vaccine brands is ok? How do we know it’s safe and it works just as well?

Question: 

How do we know that mixing COVID-19 vaccine brands is ok? How do we know it’s safe and it works just as well?

Answer: 
Mixing and matching vaccines is nothing new. Similar vaccines from different manufacturers are often used interchangeably in other routine vaccination programs. In other words, there are standards already in place to determine when mixing is safe and effective.
 
BC’s recommendations on “mix and match” are based on evidence from studies and National Advisory Committee on Immunization’s (NACI) expert opinion. Although mixing vaccines was not tested in initial clinical trials, recent real world studies have tested the safety and immune responses of mixing vaccines. Studies in Germany and the UK show the safety of mixed schedules, and a Spanish trial reported on both the safety and immune responses produced from mixed COVID-19 vaccine schedules. 
 
It’s important that you complete the vaccine series – you are not fully vaccinated until you’ve had both doses. This is because both doses are needed to get the most effective protection against serious cases COVID-19. A second dose also offers longer-lasting protection.
 
Mixing Pfizer and Moderna:
Pfizer and Moderna mRNA vaccines are effectively interchangeable and are safe and effective to mix. Read more here.
 
Mixing AstraZeneca with Pfizer or Moderna:
Current evidence shows that a first dose of the AstraZeneca vaccine followed by a second dose of an mRNA vaccine is safe and effective. However, there is a possibility of increased short-term side effects with mixed COVID-19 vaccine schedules, especially with shorter intervals. These side effects are temporary and resolve without complications. If you got the AstraZeneca/COVISHIELD vaccine first, you will have the choice of an AstraZeneca or an mRNA vaccine for your second dose. For more information to help you make that decision, check here. 
 
Date last reviewed: 
Monday, Jul 26, 2021