Canadian federal health officials deemed mixing and matching vaccines between Pfizer, Moderna, and AstraZeneca to be safe on Tuesday June 1st.
Moderna and Pfizer are mRNA vaccines, whereas AstraZeneca is a traditional vaccine made in the conventional way vaccines have been made for a long time. The National Advisory Committee on Immunization declared that if your first dose was mRNA vaccine, then your second should also be a mRNA vaccine. However, because Moderna and Pfizer are both mRNA vaccines, they’re more or less interchangeable. A mRNA vaccine can be the booster for a traditional vaccine, meaning that if your first dose was AstraZeneca, your second dose can be Moderna or Pfizer.
“For example, in Moderna and Pfizer, you use the mRNA … that gives instructions to your cells to produce the protein of the virus using genetic material, like RNA. In the case of AstraZeneca, we use what is called a harmless virus, and the virus has the protein expressed on the surface. So that is a virus that doesn’t do anything, basically, but the protein we use in order to prime or stimulate our body, is the same,” explained Horacio Bach, an infectious disease expert at UBC. (via CityNews)
This is especially comforting news for Canadians whose first dose was AstraZeneca, and thus their second dose was clouded with lots of uncertainty since Canada isn’t getting anymore AstraZeneca vaccines.
BC is set to announce its particular mix and match plan this week, on Thursday, June 3rd after NACI’s announcement.
This mix and matching isn’t unprecedented. Many countries have already adopted and executed such plans.
“This is largely based on studies that have come out of Spain and the United Kingdom. Some are looking at safety, some are looking at the immune response. I think it’s also fair to say France and Germany have been mixing and matching vaccines for at least a couple of months now. They were giving second doses of mRNA vaccines and there haven’t been any safety signals coming out of those countries,” explained Dr. Issac Bogoch, an infectious disease expert (via CityNews).