Canada to pause AstraZeneca COVID-19 vaccine use for those under 55

Canadian health officials said they would stop offering AstraZeneca's COVID-19 vaccine to people aged under 55 and require a new analysis of the shot's benefits and risks based on age and gender.

Manitoba and Quebec provinces were the first to heed the new National Advisory Committee on Immunization and Health (NACI) guidelines, with each region responsible for its own immunisation program.

"There is substantial uncertainty about the benefits of providing AstraZeneca vaccines to adults under 55 years of age," Canada's deputy chief public health officer Howard Njoo told a news conference.

"At this time, we are pausing the use of AstraZeneca vaccine to adults under 55 years of age, pending further risk-benefit analysis," he said.

Officials, meanwhile, urged Canadians who have received the AstraZeneca shot in the last 20 days to consult a doctor.

AstraZeneca said in a statement it respected NACI's decision and that it was working closely with Health Canada's assessment. The British drugmaker also reiterated that authorities in Britain, the European Union as well as the World Health Organization have found the product's benefits to significantly outweigh the risks across all adult age groups.

Njoo later noted that Canada was taking this "prudent" approach because alternative vaccines are available. Most of Canada's supply so far has come from Pfizer Inc and Moderna Inc.

Older people face a greater risk of hospitalization and death from COVID-19, and the complication seems to be rarer in that age group, NACI said, so they can be offered the vaccine "with informed consent."

Health Canada said in a statement it would add new terms and conditions to the vaccine's authorizations, including "a requirement that the manufacturers conduct a detailed assessment of the benefits and risks of the vaccine by age and sex in the Canadian context."

Health Canada said it had been in talks with AstraZeneca, and once it has the requested information, it "will determine if additional regulatory actions are necessary."

The NACI earlier this month urged giving AstraZeneca shots only to people aged 18 to 64, saying clinical trials hadn't included enough seniors, then revised its recommendation to include people of 65 and over after reviewing "real-world evidence" of its effectiveness in seniors.

The AstraZeneca vaccine candidate was approved for use in Canada in February, alongside Johnson & Johnson, Pfizer-BioNTech and Moderna shots.

The moves follow reports from Europe of rare but serious blood clots, bleeding and in some cases death after vaccination, mainly in young women. No such cases have been reported in Canada, with about 307,000 AstraZeneca doses administered.

Many European countries briefly stopped using the Anglo-Swedish firm's vaccine while investigating the blood clot incidents earlier this month. Canada continued to administer doses, arguing that the benefits of vaccination outweighed potential risks.

Nearly all countries have since resumed use of the AstraZeneca vaccine. But France broke with guidance from the European medical regulator and said on March 19 it should only be given to people aged 55 or older. France said the decision was based on evidence that the clotting affected younger people.

Canada is expecting another 1.5 million doses of the AstraZeneca vaccine this week from the United States, which has not yet authorized its use. Canada has ordered more than 20 million doses from AstraZeneca and Serum Institute of India.