NACI recommends that persons who received a first dose of the AstraZeneca/COVISHIELD vaccine may receive either AstraZeneca/COVISHIELD vaccine or an mRNA vaccine (Pfizer-BioNTech or Moderna) for their second dose, unless contraindicated. On June 1, the Public Health Agency of Canada released updated recommendations from the National Advisory Committee on Immunization (NACI) on the interchangeability of authorized...