Public health officials say the number of COVID-19 infections is rising again — just in time for the fall and winter respiratory virus season, when respiratory syncytial virus (RSV) and influenza also enter on stage.
Health Canada recently authorized an updated COVID-19 mRNA vaccine, manufactured by Moderna, that targets the Omicron XBB.1.5 subvariant currently circulating. The federal government sends the new vaccine to provinces and territories, who are responsible for rolling it out to the public.
“I think the timing is right,” said Dr. Jeffrey Pernica, chief of the division of infectious diseases at McMaster University in Hamilton. The incidence of COVID-19 has started to rise. »
It seems clear that many Canadians are tired of getting vaccinated against COVID-19: according to the Public Health Agency of Canada, only 22% of people aged five and older have received the bivalent booster dose, which offered protection against the Omicron variant in addition to the original strain of the coronavirus.
Tackling variants
Health Canada is also reviewing updated versions of two other COVID-19 vaccines.
One of them is Pfizer-BioNTech’s Comirnaty vaccine, designed to target XBB.1.5 and approved by the FDA in the United States earlier this month.
The other is a non-mRNA option. Novavax has updated its protein subunit vaccine to also target XBB.1.5. The company is still awaiting FDA approval in the United States.
The updated vaccines specifically target the coronavirus sub-variants currently circulating, which are “quite different from the original recipe,” said Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan.
The latest boosters were bivalent formulas targeting both the original coronavirus strain and BA.1 or BA.5, which are subvariants of Omicron.
But the XBB subvariants, which are the main strains currently appearing in Canada, are derivatives of Omicron BA.2 — and that subvariant was not targeted by the previous bivalent booster, Rasmussen said.
“This will do two things for people. On the one hand, this will provide them with a temporary boost in protection against infection. These will be antibodies that the booster will produce and which will be more specific than those they already have thanks to the vaccines they have received so far,” recalls the virologist.
More importantly, the vaccine will provide “additional longer-term protection against the development of severe disease”, she added.
Dr. Lawrence Loh, CEO of the College of Family Physicians of Canada, agrees.
“The variants have changed. So it’s best to be vaccinated against the one that’s circulating right now,” said Dr. Loh, who is also a family physician and former medical officer of health for Peel Region, west of Toronto.
It’s true that many people may have some hybrid immunity (dual protection with vaccination and infection) against COVID-19, doctors say.
But immunity wanes over time — so if six months or more have passed since your last infection or booster, getting the vaccine up to date is a good move to be protected this fall and winter, said Dr. Theresa Tam, Chief Public Health Officer (CPHO) of Canada at a press conference on September 12.
A question of logistics
In addition to the COVID-19 vaccine, flu vaccines will be available across the country this fall.
Like the updated COVID vaccine, the flu vaccine is formulated to match as closely as possible the strains of the virus that are expected to be circulating. Although some people can still get the flu if they are vaccinated, it still protects against serious illness, doctors say.
It is safe to receive both the COVID-19 booster and the flu vaccine, the Public Health Agency of Canada said.
Receiving both vaccines will not affect their immunological effectiveness, Rasmussen assured, noting that health care providers can administer one injection in each arm simply to minimize pain.
Health officials hope the convenience of receiving both vaccines at the same time will increase uptake of both vaccines.
“I think what we’re leaving out when we think about why people aren’t getting vaccinated is the logistics,” said Dr. Kumanan Wilson, scientific director at the Bruyère Research Institute in Ottawa and immunization researcher. Access must be made as simple as possible. »
Health care professionals are hoping to avoid the “tripledemia” that overwhelmed hospitals and doctor’s offices last fall.
However, there is currently no RSV vaccine for children, who were hit hard by the virus last year. A new RSV vaccine called Arexvy, made by GSK, is available this year for adults 60 and older. But it’s not yet clear how widely available this will be.
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