Advisory body recommends 3rd COVID-19 vaccine dose for some immunocompromised Canadians

Canada's national advisory body on vaccines now recommends giving third doses of COVID-19 vaccines to certain immunocompromised individuals, but still hasn't reached a decision on whether to provide additional shots to the broader population.

No decision reached yet on additional shots for broader population

Canada's national advisory body on vaccines now recommends giving third doses of COVID-19 vaccines to certain immunocompromised individuals. (Ted Aljibe/AFP/Getty Images)

Canada's national advisory body on vaccines now recommends giving third doses of COVID-19 vaccines to certain immunocompromised individuals, but still hasn't reached a decision on whether to provide additional shots to the broader population.

Released on Friday, the new recommendations from the National Advisory Committee on Immunization (NACI) stipulate that moderately to severely immunocompromised Canadians should be vaccinated with a primary series of three doses of an authorized mRNA-based vaccine, which includes those from Pfizer-BioNTech and Moderna.

For those who've already had a two-dose series, NACI recommends providing a third dose, ideally of an mRNA vaccine — but the committee stressed this should not be considered a "booster."

Dr. Shelley Deeks, NACI's chair, explained in a statement that the goal is providing an extra shot to people who "may have somewhat lower responses to their first vaccinations."

"This is not unusual for immunocompromised groups, where we often recommend different vaccine schedules to help them achieve better protection," she continued. "This is different from a booster dose, which would be used to boost an immune response that has waned over time."

The committee is also looking at whether additional doses might be needed for other groups, "but it is too early to comment on the state of the evidence for general boosters at this time," Deeks said.

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Debate over offering additional shots

In response to an inquiry from CBC News, Dr. Madhukar Pai, a professor of epidemiology and global health at McGill University in Montreal, said NACI's approach to limiting third doses to immunocompromised individuals is a "sensible strategy."

"I hope NACI will not suggest a [third] dose for the entire general population," he said. "That would be tough to defend from a scientific perspective and very hard to justify from a global vaccine equity standpoint."

The new recommendations come as much of the world is debating the merits of additional COVID-19 vaccine doses for various groups.

Here in Canada, some residents are already set to get third doses. Ontario and Alberta are offering additional shots for certain vulnerable populations including some transplant recipients, cancer patients, immunocompromised individuals and residents of various care homes — while Saskatchewan and Quebec are offering extra rounds of mRNA shots to people who want to travel to countries that may not recognize mixed-vaccination status.

Israel has made third doses of COVID-19 vaccine available to everyone aged 12 or older, while the U.S. plans to offer boosters to anyone eight months out from their second shot starting on Sept. 20. 

But that kind of broad approach has come under fire given the disparities in the global vaccine rollout during this pandemic.

"We're planning to hand out extra life-jackets to people who already have life-jackets, while we're leaving other people to drown without a single life-jacket," Dr. Mike Ryan, the World Health Organization's top emergencies expert, said during a recent news conference.

The European Centre for Disease Prevention and Control (ECDC) has also said there is no need to rush out booster shots for the general public because all authorized vaccines are highly protective against hospitalization, severe disease and death from COVID-19.

And other wealthy nations with ample vaccine supply have taken a slightly more nuanced approach, with France, Germany and the U.K. announcing third doses only for certain vulnerable populations.

As for the new recommendations on third doses being offered in Canada, NACI said it is referring to moderately to severely immunocompromised individuals with the following conditions:

  • Active treatment for solid tumour or hematologic malignancies.
  • Receipt of solid-organ transplant, taking immunosuppressive therapy.
  • Receipt of chimeric antigen receptor (CAR)-T-cell therapy or hematopoietic stem cell transplant (within two years of transplantation or taking immunosuppression therapy).
  • Moderate to severe primary immunodeficiency (e.g., DiGeorge syndrome, Wiskott-Aldrich syndrome).
  • Stage 3 or advanced untreated HIV infection and those with acquired immunodeficiency syndrome.
  • Active treatment with certain immunosuppressive therapies.

PHAC update on jabs for kids

"There's a very broad group of individuals who may have either an underlying health condition or a treatment that's rendered them more immunocompromised," Canada's chief public health officer, Theresa Tam, said Friday. 

Tam said recent studies show that giving someone a third dose can boost their immune response, but not everyone will get that extra protection after taking a third shot. 

She also said that while third doses of an mRNA vaccine are recommended for some, people who cannot take that kind of vaccine can speak with their family doctor about taking a viral vector vaccine such as AstraZeneca. 

Dr Howard Njoo, Canada's deputy chief public health officer said clinical trials looking at immunization for children aged 5 to 11 are ongoing and results will start coming back in the fall. 

Once the trials are complete the data has to be reviewed by Health Canada officials, and Njoo said final approval of jabs for kids could come toward the end of the year at the earliest if all regulatory hurdles are met. 

"That's maybe being optimistic, but certainly we anticipate that something would be coming forward certainly for next year. But hopefully, if everything goes well, maybe more towards the end of this calendar year, but it's wait and see on that front," he said. 

With files from Adam Miller, CBC News

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