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NACI advises boosters for those over 50, says 18 to 49-year-olds may receive one also

Canada's immunization advisory panel now strongly recommends everyone at least 50 years old get a booster dose of the COVID-19 vaccine and that it may be offered to all other adults too in response to reports of waning protection against the virus.
A registered pharmacist technician carefully fills the Pfizer-BioNTech COVID-19 mRNA vaccine at a vaccine clinic during the COVID-19 pandemic in Toronto on Tuesday, December 15, 2020. The National Advisory Committee on Immunizations is set to release new guidance this morning on the use of COVID-19 vaccine boosters as public health faces down the threat of the new Omicron COVID-19 variant. THE CANADIAN PRESS/Nathan Denette

OTTAWA – Canada's immunization advisory panel now strongly recommends everyone at least 50 years old get a booster dose of the COVID-19 vaccine and that it may be offered to all other adults too in response to reports of waning protection against the virus.

The National Advisory Committee on Immunization (NACI) expanded its list of who should be eligible for the extra shots on Friday, now also strongly recommending them for front-line health workers, those who received a full series of the Oxford-AstraZeneca or Janssen vaccine and those in or from First Nations, Inuit and Métis communities.

The group also said that people between the ages of 18 and 49 may be offered a booster dose of a mRNA vaccine at least six months after they are fully vaccinated.

The advisory committee had already strongly recommended boosters for people who are immunocompromised, live in long-term care centres and people over the age of 80.

The new recommendation was released after an urgent request from the federal government for information on the role of COVID-19 vaccine boosters in fighting the new Omicron variant, though NACI had already been working on updated advice.

Omicron, which came to light late last week, sparked tougher border measures around the world.

"I think there is a need, and I would say a responsibility, for NACI at the federal level to help provinces come closer together in answering the questions of Canadians around booster shots," federal Health Minister Jean-Yves Duclos said Friday.

The World Health Organization has warned the high number of mutations could signal that it is more transmissible than previous strains.

Cases of Omicron have already cropped up across the country. Though most involve recent travel, one case, reported in Alberta, involved household transmission.

NACI recommends people get a booster of an mRNA COVID-19 vaccine six months after their second shot. 

NACI's analysis shows the vaccine offers waning protection against infection and transmission over time. Some studies show decreases in protection against serious infection and more notably in older adults.

"The bottom line is that if there is waning immunity over time … an additional dose or boost to your immune system helps, at least in the short term, boost your antibody levels and increase the quality of your overall immune response and the durability of the response," Dr. Theresa Tam, Canada's chief public health officer, said at a briefing Friday. 

Dr. Howard Njoo, the deputy chief public health officer, said there are already emerging indications that immunity is waning.

With highly transmissible variants like Delta and Omicron, NACI says breakthrough infections, particularly in communities with low vaccine coverage, can lead to high community rates of COVID-19.

"This can have significant impacts, especially on populations at high risk of COVID-19 illness and on health system capacity," NACI said in its report Friday.

Though these latest recommendations were only published Friday, many provinces have gone ahead with their own COVID-19 booster strategies and in some cases have already pledged to offer them to any adult who wants one in the coming weeks.

Provincial plans must also take into account their own demographics and health system capacity, and they have the difficult job of balancing those factors with the scientific evidence, said Tam.

"Everyone has been trying to focus on the groups at highest risk. And I hope that the NACI recommendation is very helpful to the provinces and territories, and I think begins to provide some guidance as to which age groups should receive the strongest focus," she said. 

Duclos said Friday that he hopes the NACI advice will help provinces harmonize their approach.

It's too early to say yet whether COVID-19 vaccine boosters will become a routine part of Canadian life in the months and years ahead, according to health officials. It's also possible that in the future people won't be considered fully vaccinated until they've received three vaccine doses. 

Though clinical trials for booster shots did not include pregnant and breastfeeding women, they are also included in the recommendation. 

NACI also favours Pfizer over Moderna when it comes to boosters for people 18 to 29 years old because of slightly higher instances in rare cases of heart inflammation associated with Moderna recipients in that age range. 

Prime Minister Justin Trudeau said Wednesday when it comes to boosters, the priority is to follow NACI's advice on who should get them, and when, in light of the Omicron variant.

Vaccine supply will not be an issue, he said.

"We have lots of vaccines for boosters in Canada, we're receiving more into the new year. We are fine in terms of quantity. The issue is, what is the best recommendation for people to get those boosters and when," he said.

NACI did consider the ethical question of recommending boosters for healthy adults in Canada when the virus is running rampant in parts of the world where many high-risk people have yet to receive a first dose. 

The World Health Organization has urged countries to delay boosters as long as possible, except for high-risk people, and to prioritize support for countries struggling to vaccinate their populations instead.

"I think that that's what we're seeing in the advice today from the committee: an emphasis on those where the risk will be greatest and the need is greatest, and then also creating opportunities for others 18 to 49 years of age," said Matthew Tunis, executive secretary to NACI.

Tam said younger populations likely won't qualify for a booster until 2022 anyway, because they will have to wait six months since they received their last dose.

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

Laura Osman, The Canadian Press