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‘First-dose-first’: Panel reassures Canadians 16 weeks between COVID-19 vaccine shots is safe – The Guardian

‘First-dose-first’: Panel reassures Canadians 16 weeks between COVID-19 vaccine shots is safe – The Guardian

Canada’s vaccination advisors aren’t walking back a controversial “first-dose-first” COVID vaccine strategy of spacing shots up to four months apart, arguing it’s critical to get at least one dose into more bodies as quickly as possible.

Last month, the National Advisory Committee on Immunization, or NACI, endorsed stretching the interval between doses up to 16 weeks — a gap longer than any other country — to get a greater proportion of the population at least partially vaccinated. The original, and officially authorized, recommended window was 21 days between doses for Pfizer-BioNTech’s’s vaccine, and 28 days between Moderna shots.

Most provinces responded accordingly and are stretching doses up to four months.

On Wednesday,

the panel stood by its earlier “rapid response” recommendation

, saying delaying the second shot will bring faster population-level protection.

Protection from the first dose of a two-dose series can last at least six months and a longer interval between shots generally results in a better immune response after the second, booster dose, said Dr. Shelley Deeks, co-chair of the independent advisory panel.

Deeks said a second dose should be offered as soon as possible, once all eligible groups have had a first dose, and priority should go to those at highest risk of sickness or death from COVID-19.

“With Canada’s expected vaccine supply, the interval between the first and second dose is expected to be less than four months,” she said. It’s still crucial that Canadians receive a second dose as quickly as supply allows, the panel said.

“We all want to return to a sense of normalcy,” said Dr. Bonnie Henry, B.C.’s provincial health officer and chair of the Council of Chief Medical Officers of Health. Injecting as many people as possible with a first dose “means that we can provide high level protection to more people, more quickly, saving lives” and reducing illness, Henry said.

“As chief medical officers of health, we welcome and support NACI’s recommendation to extend the timing of second dose of COVID-19 vaccine up to four months,” she said.

Some have called the strategy a risky, population-level experiment. Some studies suggest delaying the second dose leaves older people with a weaker immune response.

“I think it makes total sense that the people who are highest risk, you don’t want to space it out,” infectious diseases specialist Dr. Andrew Morris said recently. “We should be narrowing the interval for people over age 60, probably, and those with underlying active cancer and organ transplant recipients. I think that definitely should change.”

There is also some concern that if people are only partially immunized it could fuel more variants.

However,

a paper published in Nature

suggests it’s unlikely “dose sparing” strategies would lead to variants that could escape vaccine protection and that it might even lower the risk. “Moreover, even under worst-case evolutionary scenarios, residual immunity from dose-sparing strategies should reduce the burden of COVID-19 disease,” the researchers wrote.

“The risk is actually not seen — if it’s there it’s less than the risk of not vaccinating more people with one dose,” said Dr. Caroline Quach-Thanh, NACI’s co-chair.

A longer interval between shots leads to longer lasting protection, Henry said. “It may turn out that the optimal dosing is actually five months or six months,” she said. “We’re learning as we go.”

Most adults are expected to get their first dose by mid-June, Deeks said. “There is no magic time point at four months or three months,” she said. “Right now, the effort and energy is getting the first dose in as many arms as quickly as possible.”


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Copyright Postmedia Network Inc., 2021

Published at Wed, 07 Apr 2021 17:23:27 +0000

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Written by Riel Roussopoulos

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