With cases rising across the province, should you get your fourth dose now, or wait for the booster doses scheduled for the fall, adjusted to the new variants? Experts help us see things more clearly.
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“Healthy people who have received their third dose are generally well protected. They can afford to wait a bit,” says Nathalie Grandvaux, a researcher at the Research Laboratory on the Host Response to Viral Infections at the University of Montreal Hospital Center (CHUM).
The DD Caroline Quach-Thanh, a professor in the University of Montreal’s Department of Microbiology, Infectious Diseases and Immunology, agrees. “A person who has already received three doses of vaccine and been infected with Omicron remains protected about 90 to 95%. She could fully pick up her fourth dose in the fall,” she says.
However, individuals’ occupations can have an impact, says Frau.me Grandvaux. “If anyone decides to travel or visit vulnerable people this summer, it would be a good time to go get them,” says the specialist.
In Quebec, people 18 and older can receive a fourth dose or a second booster three months or more after the previous one. Dialysis patients from the age of 12 or people with a weakened immune system can also be affected.
However, for people over 60 and at risk, the experts agree: you should take the fourth dose as soon as possible.
“Given the increase in cases and the transmissibility of the variants circulating, it’s a good thing to get it,” says Dr.D Chantal Sauvageau, Infectious Disease Medical Advisor at the National Institute of Public Health of Quebec (INSPQ).
During a news conference last week, the national director of public health, Dr.right Luc Boileau also invited immunocompromised people, those aged 60 and over and those suffering from a chronic disease to receive a fourth dose of the vaccine against COVID-19 if they have not already done so.
The arrival of new vaccines
All vaccines currently in circulation are based on the parent strain of the virus and have gradually been shown to be less effective against variants that have evolved over time. Moderna and Pfizer have therefore developed Omicron and its sub-variants specific refresher doses that could be offered as early as autumn.
“We know we’re going to have six million doses in Canada, so there won’t be enough for everyone,” specifies the DD Quach thanh. Those doses could be offered beginning in late August, according to Health Canada’s decision, she says.
Should we wait for the arrival of booster doses adapted to Omicron? Not necessarily, say the experts. “We were hoping there would be no cases this summer but there is a spike and it’s only early July. If it is appropriate to get vaccinated now, I think we must do it, regardless of what will happen in the fall,” said André Veillette, a professor at the University of Montreal School of Medicine.
A magic formula?
On June 22, Moderna claimed that its new COVID-19 booster vaccine candidate, which the company hopes will be approved in the fall, is effective against the latest Omicron subvariants.
This new formula is what is known as a ‘bivalent’ vaccine, meaning it targets both the original strain of the virus – like the vaccine previously given around the world – and the Omicron variant.
This boost showed a more than five-fold increase in neutralizing antibodies against the BA.4 and BA.5 subvariants. However, even these high levels were only a third of what was achieved over the original Omicron strain, BA.1.
However, experts warn against getting excited too quickly. “Will this small increase in antibodies be magical? No, I don’t think so,” says the DD wild. The DD Quach Thanh second. “It’s a good vaccine, but to say it will completely change the game, we’re not convinced of that,” she said.
For his part, the general director of Moderna, Stéphane Bancel, announced that he would transmit these data to the supervisory authorities “as a matter of urgency”. “We are preparing to deliver our next-generation bivalent booster starting in August, ahead of a possible early fall surge in SARS-CoV-2 infections due to Omicron subvariants,” he said in a statement.
Pfizer-BioNTech is also conducting trials of an “updated” version of its vaccine specifically targeting Omicron. The alliance said it could start producing such vaccines within three months.
With Agence France-Presse, The Associated Press and The Canadian Press