TORONTO: The health minister of Canada’s most populous province said Tuesday Ontario seniors won’t receive the Oxford-AstraZeneca vaccine since there’s limited data on its effectiveness in older populations.

Health Minister Christine Elliott said Ontario plans to follow the advice of a national panel that’s recommended against using the newly approved vaccine on people aged 65 and older. She said anyone over that age is recommended to receive either the Pfizer or the Moderna vaccine.

Canada’s regulator approved the Oxford-AstraZeneca last week for all adults including seniors, but the National Advisory Committee on Immunization said this week that the vaccines from Pfizer-BioNTech and Moderna are preferred for seniors due to “suggested superior efficacy.”

Health authorities in France and Germany and other countries have also raised concerns that AstraZeneca didn’t test the vaccine in enough older people to prove it works for them, and indicated they would not recommend it for people over 65. Belgium has authorized it only for people 55 and under.

France said this week it will allow some people over 65 to receive the AstraZeneca coronavirus vaccine, after initially restricting its use to younger populations because of limited data on the drug’s effectiveness. Last month, South Africa scaled back its planned rollout of the AstraZeneca vaccine, opting instead to use an unlicensed shot from Johnson & Johnson for its health care workers.

The Canadian Pacific Coast province of British Columbia, meanwhile, plans to delay the second dose of COVID-19 vaccine to four months. Ontario and Alberta are also considering following the province’s lead.

Dr. Bonnie Henry, British Columbia’s provincial health officer, said the decision was “made in the context of limited supply and based on strong local and international data.

“This makes sense for us, knowing that it is a critical time right now with the limited amount of vaccines that we have in the coming weeks, to be able to provide that protection ... to everybody here,″ Henry said.

Chief science adviser Mona Nemer told the Canadian Broadcasting Corporation that British Columbia’s plan amounts to a “population-level experiment” and that the data provided so far by Moderna and Pfizer-BioNTech is based on an interval of three to four weeks between doses.

Henry said the manufacturers structured their clinical trials that way to get the vaccines to market as quickly as possible, but research in B.C., Quebec, Israel and the United Kingdom has shown that first doses are highly effective.

The B.C. Centre for Disease Control examined the effects of a single dose on long-term care residents and health-care workers and found that it reduced the risk of the virus by up to 90% within two to three weeks, Henry said.

Dr. Danuta Skowronski, a B.C. Centre for Disease Control epidemiology lead whose work underpinned the province’s plan, said Pfizer-BioNTech underestimated the efficacy of its first dose in its submissions to the U.S. Food and Drug Administration.

Skowronski said the company included data from the first two weeks after trial participants received the shot, a time when vaccines typically aren’t effective. When she and her colleagues adjusted the data, they found it was 92% effective, similar to the Moderna vaccine.

Canada started vaccinating health care workers and the elderly in long-term homes in December but there’s been a shortage of vaccines until now. Many Canadians are not expected to be vaccinated for months. Prime Minister Justin Trudeau hopes to vaccinate all Canadians who are eligible by the end of summer.