Vaccine advisers set to provide guidance on mixing AstraZeneca, mRNA vaccines today

OTTAWA — The National Advisory Committee on Immunization is set to issue guidance today allowing for people who received the Oxford-AstraZeneca vaccine as their first dose to get an mRNA vaccine for their second.

A study in the United Kingdom reported last month that mixing AstraZeneca and Pfizer-BioNTech as first and second doses led to more reports of short-lived side-effects like fevers and fatigue but was otherwise safe.

The Spanish study concluded a second dose of Pfizer after a first dose of AstraZeneca produced more than twice the antibodies as a second dose of AstraZeneca.

All provinces paused the use of AstraZeneca for first doses in May as reports of vaccine-induced blood clots rose, but are anxiously waiting for the NACI advice on what to do with second doses.