by Rachel Aiello
OTTAWA - Health Canada has authorized the use of the country's first variant-targeting COVID-19 booster shot.
On Thursday, the federal health regulator announced it has given the green light to Moderna's Omicron-targeting bivalent COVID-19 vaccine, for those ages 18 years and older.
The "Spikevax Bivalent" booster dose targets both the original strain of COVID-19 as well as the Omicron variant. The mutated and highly-transmissible version of the novel coronavirus has been widely circulating in Canada since November 2021.
Health Canada said, according to a study comparing individuals immunized with the bivalent shot and those who received the original Moderna mRNA dose, the findings indicated that the updated vaccine "provides better immune response to the Omicron BA.1."
According to authorization information published by Health Canada, the proposed dosing regimen is an interval of "at least four months following a primary series and/or previous booster dose."
Given as an intramuscular injection — consistent with other COVID-19 vaccines — the 50 microgram dose can cause common side effects including pain, swelling or redness at the injection site, as well as fatigue, muscle aches and stiffness, fever, and chills.
A technical briefing with Public Health Agency of Canada officials is scheduled for Thursday morning. Then, Health Minister Jean-Yves Duclos will be making an announcement about "the importance of COVID-19 vaccination as we head into the fall."
Moderna submitted its bivalent booster to Health Canada for regulatory approval on June 30. While the booster shot was submitted by Moderna for approval for ages 12 and over, it appears Health Canada has decided to limit its authorization for use in adults.
The federal health agency is cautioning against receiving this shot if you have had an allergic reaction to a previous dose of Moderna's COVID-19 vaccine.
Moderna's bivalent shot will be the first such vaccine available in Canada. Pfizer-BioNTech has also submitted its bivalent booster for regulatory assessment. That submission went to Canada’s federal health regulator on July 25, and while authorization could be imminent it is not expected to be part of Thursday's announcement.
"Our regulatory colleagues in Health Canada are working very fast at reviewing the submissions from Moderna and from Pfizer-BioNTech on the bivalent booster doses," said Chief Public Health Officer Dr. Theresa Tam during a press conference on Aug. 22.
This decision comes on the heels of the U.S. Food and Drug Administration granting emergency use authorizations on Wednesday, to both Moderna and Pfizer's bivalent vaccines for use as single booster doses at least two months following primary or booster vaccination.
The United Kingdom approved the Moderna bivalent vaccine on Aug. 15.
The federal government has already purchased 12 million doses of the vaccine, making an agreement with Moderna to replace some of the planned supply of the original mRNA shot with the newer version, with delivery expected before the end of the year.
As has been the case throughout the pandemic, provincial health authorities will be responsible for determining their rollout of this shot, and who'd be prioritized to receive it.
Questions have been raised about whether Canadians should be waiting for the bivalent doses to become available before rolling up their sleeve for a shot, something Tam has said should be decided based on individual risk factors.
"The exact timing of the booster doses and appropriate populations to administer booster doses to will depend on a variety of factors, including the local epidemiological contexts which are continually evolving and may vary between provinces and territories," said Health Canada in its regulatory decision summary.
With pandemic restrictions largely lifted across provinces, and Canadians expected to increasingly spend more time indoors, doctors and epidemiologists are cautioning against a rise in COVID-19 cases this fall and winter.