COVID-19 vaccine: Quebec halves interval between first and second doses to 8 weeks

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MONTREAL — Medical experts praised the Quebec government's decision on Thursday to shorten the interval between doses of COVID-19 vaccines to eight weeks from 16.

"I think it's very good news," said Dr. André Veillette, director of the molecular oncology research unit at the Montreal Clinical Research Institute and a member of the federal government's COVID-19 vaccine task force.

With the spread of the "delta" variant of the novel coronavirus — the variant first detected in India — getting people vaccinated with two doses quickly is important, Veillette said in an interview Thursday.

The first dose of a COVID-19 vaccine offers less protection against that variant than against other variants — including the one first detected in the United Kingdom, which is widespread in Quebec — but protection increases significantly with a second dose, he added.

Veillette said getting people fully vaccinated over the next three months is important to help prevent a wave of the virus driven by the delta variant. "That's why I think we need to, right now, push on the gas pedal as much as possible and accelerate this vaccination," Veillette said.

The provincial Health Department said it is shortening the minimum interval between first and second doses of the Pfizer-BioNTech and Moderna mRNA vaccines to eight weeks from 16. Last week, it shortened the interval in the same way for the Oxford-AstraZeneca vaccine.

Quebecers will be able to reschedule their appointments for a second dose of an mRNA vaccine starting June 7, Health Minister Christian Dubé told reporters Thursday in Quebec City alongside Daniel Paré, head of Quebec's vaccination campaign. Second-dose appointments will be rescheduled in descending order of age, Dubé said.

Paré estimated that "over three million Quebecers" will probably advance their second-dose appointments. He said that with the federal government's current vaccine delivery schedules, he is confident the province will have sufficient supplies of all three authorized vaccines.

People 80 and older are first in line to reschedule their dates, and then the province's online-booking system will open to Quebecers in five-year age blocks each weekday until June 23, when people as young as 18 will get their turn.

Dr. Donald Vinh, an infectious disease specialist at the McGill University Health Centre, said an interval of two to three months between doses is ideal to take advantage of an important immunological reaction to the first dose of a COVID-19 vaccine. Giving the booster shot while that reaction is ongoing helps the body produce a large number of high-quality antibodies, he added.

"It's ideally what we should have done at the beginning," he said in an interview Thursday. The shorter interval, he said, means "we have people who will get their second dose sooner, rather than later, and … assuming the uptake remains good, you will have a larger proportion of people who are fully vaccinated earlier."

People who are fully vaccinated are not only more protected, Vinh said, they're also less likely to spread the virus than people who have only been partially vaccinated.

Dubé said the government hopes to be able to fully vaccinate 75 per cent of Quebec residents over 12 before the end of August. "We want to go back to school, we want to remove those masks, we want to do all those good things, Dubé said. "So that's what the second dose is, it's that return to, I would say, quasi-normality."

More than 75 per cent of adults in Quebec have received a first dose of vaccine — three weeks earlier than the province had originally planned, Dubé said. "We're very happy," he added. "We have achieved our first objective."

Meanwhile, health officials Thursday reported a 23-patient drop in COVID-19-related hospitalizations, for a total of 317, including 68 people in intensive care, a drop of nine. Officials also reported 267 new COVID-19 infections — the fourth consecutive day new cases dropped below 300 — and six more deaths attributed to the novel coronavirus, including one within the previous 24 hours.

The province said 85,230 doses of vaccine were administered Wednesday, for a total of 5,808,464.

Earlier on Thursday, Premier François Legault said graduation balls for high school students — which had been banned this year by public health authorities — may be able to go ahead in some form.

"I've asked public health to try to find a compromise, because I understand how important it is for young people," the premier told reporters in Quebec City.

This report by The Canadian Press was first published June 3, 2021.


This story was produced with the financial assistance of the Facebook and Canadian Press News Fellowship.

Jacob Serebrin, The Canadian Press