Canada’s National Advisory Committee on Immunizations says it’s safe for Canadians to mix COVID-19 vaccine types.
Dr. Theresa Tam, Canada’s Chief Public Health Officer, announced Tuesday anyone with their first dose of AstraZeneca can receive an mRNA vaccine like Pfizer-BioNTech or Moderna, for their second dose.
Those who received a first dose of a mRNA vaccine are advised to get a second dose of the same type, but if they are unavailable when it comes time for the second shot Tam said Pfizer and Moderna can be ‘considered interchangeable.’
“The interchangeability of vaccines means you can receive one vaccine product for your first dose, and safely receive a different vaccine for your second dose to complete your two-dose vaccine series for optimal protection from COVID-19,” Tam said.
As provinces reach the threshold of offering first doses to all Canadians aged 12 and older, Tam says it’s now important to turn our attention toward getting second doses into the arms of the most vulnerable residents.
“The committee recommended last week that second doses be offered as soon as possible. NACI recommends that priority for second doses should be given to those at highest risk of severe illness and death from COVID-19 disease after or at the same time as first doses are offered to all remaining eligible populations,” Tam said in a press briefing.
The announcement follows studies and clinical trials into vaccine interchangeability in Germany, Spain and the United Kingdom.
Updated guidance from NACI says those studies show following a dose of AstraZeneca with a mRNA vaccine provides an immune response boost, though there is a possibility of increased short-term side effects, including headache, fatigue and general illness.
Studies have also shown that while the risk of VITT or blood clots caused by vaccines appears to be lower from a second dose, the rate has increased over time. NACI says the second dose of AstraZeneca appears to trigger VITT in 1 out of every 600,000 people who received the shot.
NACI also says so long as Canadians receive two doses of any of the three currently-approved COVID-19 vaccines that individual should be considered to be fully vaccinated from COVID-19.
Individual provincial governments will now have to consider NACI’s guidance and determine whether they will offer residents the opportunity to mix vaccine types for their second doses.
1/5 The National Advisory Committee on Immunization (NACI) has updated its recommendations on the interchangeability of #COVID19vaccines for second doses following studies from Germany, the U.K, and Spain.
https://t.co/U9HV5J92Rs pic.twitter.com/pcaemrbfNa
— Dr. Theresa Tam (@CPHO_Canada) June 1, 2021
