Is it safe to mix vaccines?
It is safe to mix the COVID-19 vaccines. Mixing vaccines is not a new idea. It has been done in the past with Ebola, flu shots, and hepatitis vaccines.
Mixing Astrazeneca with mRNA
New evidence suggests mixing AstraZeneca with an mRNA vaccine (Pfizer, Moderna) is highly effective and safe. There is also no known risk of blood clots with the Pfizer or Moderna vaccines. If you got Astrazeneca as your first dose, it is recommended you get either Pfizer or Moderna as your second dose. However, you can also get a second dose of Astrazeneca if you had no severe issues with your first dose. Once you have two doses, you are fully vaccinated and have the greatest protection against COVID-19.
Mixing mRNA with mRNA
The mRNA vaccines (Pfizer, Moderna) can also be mixed because they are so similar. Vaccines from different companies can be mixed when they:
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Have the same purpose
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Are used in the same populations
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Work in the same way
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Are equally safe
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Are equally effective
Looking at all these characteristics, the Pfizer and Moderna vaccines are pretty much the same. This means that if you got Pfizer as your first shot, you can get Moderna as your second. If you got Moderna first, you can get Pfizer second.
The most important thing is to get the first vaccine available to you!