Health Minister Jean-Yves Duclos and Canada's top doctor said Thursday that it's imperative everyone eligible for a booster dose gets their third shot now before the new, more infectious Omicron variants take hold in the coming weeks.
Dr. Theresa Tam, Canada's chief public health officer, said while COVID-19 case counts are currently stable, officials are bracing for a resurgence in late summer and early fall as immune-evasive variants like BA.4 and BA.5 become widespread and the country enters the respiratory virus season.
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Tam said the best defence against this expected wave is getting up to date with COVID-19 shots.
The primary series of shots — the first doses of a COVID-19 vaccine — don't offer enough protection and a third dose is needed for all adults and for certain high-risk adolescents, she said.
Government data suggests the first two shots offer little protection against an Omicron infection — "There's almost no protection," Tam said earlier this month — and data from other countries similarly suggest the primary series offers negligible levels of protection against transmission.
The first two doses do offset the possibility of severe outcomes like hospitalization and death but that protection wanes substantially over time, necessitating a third dose to jump start the immune response, Tam said.
Canada lags other countries in booster dose coverage
Tam said the benefits of a third dose are already well known. She said, based on data collected in April and May of this year, when Omicron activity was very high in Canada, people with a booster shot were five times less likely to be hospitalized and seven times less likely to die from the virus than the unvaccinated.
Canada is lagging behind other developed countries in booster dose coverage. According to Duclos, only 60 per cent of adults who got their first two doses have gone back for a third. The rates are substantially higher in other countries like Japan and the U.K.
"We're behind most other G7 countries in our rate of third doses and we shouldn't be behind, we've been ahead of all those other countries with two doses. We know we have the capacity to do better and we will be doing better," Duclos said.
"As any physician or health expert will tell you, it's critical you go and get the shot that's waiting for you. Like the virus, immunity also evolves and Omicron has cruelly made us understand that two doses is no longer enough."
Duclos said every Canadian adult should have had at least one dose of a COVID-19 vaccine in the last nine months. Canadians who got a shot last summer are no longer "up to date," he said, and they need to roll up their sleeves now for a booster.
To that end, Duclos said Canada will no longer call people who've had two doses "fully vaccinated." But he didn't say if the government's vaccine mandates will be adjusted to dictate people have three doses of a COVID-19 vaccine.
Past COVID infection doesn't offer enough protection: Tam
The National Advisory Committee on Immunization (NACI), the body of independent experts that guide Canada's vaccine policy, strongly recommends all adults get a booster dose.
If a person has had a COVID infection, they should wait three months from diagnosis to get that booster dose, the committee has said.
A past COVID infection doesn't offer enough protection, Tam said. She said some Canadians are under the false impression that two doses of a COVID vaccine plus a past infection offers sufficient coverage.
"Infection-related immunity, particularly as it relates to Omicron, could wane over time. There are many other reasons as well to get a shot," Tam said, citing the possibility that a booster dose could lower the risk of people developing long COVID symptoms.
Tam said Canadians also shouldn't wait for an Omicron-specific vaccine.
While major vaccine manufacturers like Moderna and Pfizer are currently developing products that are tailored to the current strain, Tam said it could be months before the product is approved by Health Canada regulators for use in this country.
She also said those vaccines may not offer much more protection against Omicron than what's already available.
"There is still considerable uncertainty about the exact timing and availability of new formulations," said Dr. Matthew Tunis, the executive secretary to NACI. "The committee is unable to predict how the future will unfold."