Canada Recommends Pfizer, Moderna As Second Dose After AstraZeneca

New evidence suggests people respond better to an mRNA vaccine after receiving the AstraZeneca shot.

A Canadian advisory committee says Canadians who got the AstraZeneca shot for their first vaccine dose should not get the second one. It says they should get the Pfizer or Moderna vaccine for their second shot instead. The vice-chair of the board says new evidence suggests responses are better when the AstraZeneca vaccine is followed by an mRNA vaccine and said the new guidance also takes into account the marginal risk of blood clots associated with AstraZeneca.