Canada: Pfizer, Moderna preferred 2nd dose after AstraZeneca

Canada’s National Advisory Committee on Immunization says it is now recommending people who got the AstraZeneca vaccine first should get Pfizer-BioNTech or Moderna for their second shot

OTTAWA, Ontario -- Canada's National Advisory Committee on Immunization said Thursday people who got the AstraZeneca vaccine as their first dose should get Pfizer-BioNTech or Moderna for their second shot. On June 1, committee had said AstraZeneca recipients “could" get Pfizer or Moderna for their second shot if they wanted, but Thursday went further to say an mRNA vaccine was the ”preferred" choice. Since the advisory committee "first looked at mixed vaccine schedules, new evidence is starting to emerge suggesting immune responses are better when a first dose of the AstraZeneca vaccine is followed by an mRNA vaccine as a second dose,″ said its vice-chair Dr. Shelley Deeks, in the new guidance documents. The committee also updated its previous recommendation that people at high risk of exposure to, or serious illness from, COVID-19, could opt to get AstraZeneca rather than waiting for Pfizer or Moderna. Now it says everyone should always get the mRNA vaccines first, unless they are allergic to them.