Expectations are rising for Canada to approve an updated version of the COVID-19 vaccine as the fall threatens to usher in a new wave of infections.
Earlier this week, British regulators became the first in the world to approve Moderna’s bivalent vaccine, which protects against both the original strain of the new coronavirus and the Omicron BA.1 subvariant.
Health Canada is currently reviewing bivalent booster candidates from Moderna and Pfizer-BioNTech, which is leaving some Canadians debating whether to wait for the renewed shots or get a booster now.
With circulation of the virus expected to increase as the season changes, some provinces are encouraging people to get a booster shot of the approved version of the vaccine.  For many people, this would mean a fourth or fifth dose of the original formula.
Experts say the extent to which bivalent vaccines provide additional protection against catching COVID-19 is still being studied, and the cost-benefit analysis of waiting for a vaccine depends on the individual.
Here’s a look at what we know about bivalent vaccines and how they could lead to a wave of decline.
WHEN WILL POSSIBLE VACCINES BE AVAILABLE?
Health Canada received Moderna’s bivalent vaccine application on June 30, while its British counterpart received the documents to begin its review earlier this month, spokesman Mark Johnson said in an email.  Pfizer submitted a submission for its updated take on July 25.
Although the agency did not provide a timeline for when these revisions will be completed, Health Canada has already asked vaccine manufacturers to further modify their bivalent vaccines to target the rapidly spreading Omicron BA.4 and BA.5 subvariants. as soon as possible,” Johnson said.
Canada’s chief public health officer, Dr. Theresa Tam, says Canada has secured an “adequate” supply of bivalent vaccines if regulators want to go ahead with the release.
Infectious disease expert Dr. Zane Chagla said he expects to see more countries approve bivalent vaccines in the coming weeks and months, which will give Canada time to incorporate the updated vaccines into its fall immunization campaign.
HOW DO BIPOTENTIAL AGENTS COMPARE TO ORIGINAL VACCINES?
Currently available vaccines for COVID-19 are univalent – ​​tailored exclusively to the original novel coronavirus.  In addition to defending against this earlier strain, the proposed bivalent vaccines were designed to recognize specific mutations in the Omicron spike protein that make it better at evading immune detection.
These updated vaccines may provide “incremental” additional protection from catching Omicron, but the extent remains to be seen, Tam said.
Chagla, an associate professor at McMaster University in Hamilton, said bivalent vaccines may not be the game-changer some hoped for in curbing the spread of the virus.
As Omicron’s BA.4 and BA.5 subvariants gain steam across much of the country, BA.1-adapted bivalent vaccines may not be much better than a first-generation booster in preventing COVID-19 infection, Chagla said.
Emerging research shows that the protection provided by available boosters wanes within six to eight weeks, Chagla said.  He expects bivalent vaccines could extend that period by a few extra weeks — not months.
“I’m glad to be proven wrong,” he said.  “But I don’t know if that will turn the clock back.”
Both the old and new versions of the COVID-19 vaccines are effective in preventing severe COVID-19 outcomes, he noted.
SHOULD I WAIT TO GET DOUBLE VACCINE?
The short answer is: it depends.
Provinces have expanded access to fourth — and in Quebec, fifth — doses of the original COVID-19 vaccine in anticipation that COVID-19 cases will increase as temperatures drop.
With the health care system already stretched to its limits, the priority must be to boost those at highest risk of landing in the hospital, such as the immunocompromised and the elderly, Chagla said.
But since a larger portion of the population has acquired hybrid immunity, it would not be unreasonable for low-risk people to wait for the latest version of the vaccine, Chagla said.
Tam encouraged Canadians to weigh both their personal risks and the level of spread of COVID-19 in their community.  But if it’s been more than six months since your last infection or vaccination, you may want to roll up your sleeves for another shot before the cold weather hits, he said.
“If you waited too long, the wave could start,” he said.  “Then you don’t get as much benefit.”
WHAT’S NEXT?
A key challenge in controlling COVID-19 is that the evolution of the virus has far outstripped the time needed to develop, test, manufacture, revise and release a vaccine that can neutralize the latest mutation.
“Until the wave comes out — two to three months — that’s just enough to scratch the surface of a new vaccine’s uptake,” he said.  “There’s this catch-up game going on all the time.”
He hopes the initial launch of the bivalent vaccines could provide a “proof of concept” that will speed up that process for future iterations of the vaccine, similar to how the flu vaccine is tweaked each fall to target variants that are released.
“There’s nothing wrong with it being a flu-season-like model where people are just informed for a certain amount of time,” he said.
While we can’t expect perfect protection from getting sick, we can have the tools to prevent serious illness among the most vulnerable.
“We’re lucky to have this technology.”
This report by The Canadian Press was first published on August 20, 2022.