NACI recommends Pfizzer of Moderna for people who received AstraZeneca as first COVID-19 vaccine shot

Canada’s chief public health officer Dr. Theresa Tam announced on Thursday that the National Advisory Committee on Immunization (NACI) has updated its guidance for people who received an AstraZeneca COVID-19 vaccine first shot to recommend receiving an mRNA vaccine as a second shot, either a Moderna or a Pfizer vaccine, citing an emerging evidence on potentially better immune response with this mixed vaccine schedule.