Chief Public Health Officer Theresa Tam looks on during a technical briefing on the COVID-19 pandemic, in Ottawa, Friday, Jan. 15, 2021. THE CANADIAN PRESS/Adrian Wyld

Canada's top doctor says there's concern that an increase in more transmissible variants of the COVID-19 virus may be threatening the country's progress in containing the spread of infections.

And while Canada's vaccine rollout has been gaining speed over the past few weeks, Dr. Theresa Tam says the country is in a "crucial moment" in the battle between vaccines and variants.

"If we don't slow down the spread of the variants, Team Vaccine is at risk of falling behind," Tam said in a press conference Friday.

"But if we can hold on and give it that last push, by keeping up with personal protective measures and limiting our contacts to the extent possible, we will clear the path for Team Vaccine to cross the finish line."

There have been nearly 4,500 variant cases of COVID-19 in Canada, with 90 per cent of those related to the variant first detected in the U.K., Tam said, adding that in parts of Canada, variants of concern are making up a higher proportion of all new cases.

The country's vaccination rollout, while still reaching only a small minority of Canadians, has been having some positive effects, she added.

Ontario expanded vaccine rollout plans Friday, broadening the age groups that will be eligible for their first vaccine doses starting next week, while Quebec opened up vaccinations to anyone 65 and older.

Tam said rates of COVID-19 are dropping in people 80 years of age or older, and there is a "downward trend" in outbreaks at long-term care homes.

"Each week a new high is being set for the number of COVID-19 vaccine doses administered with over 670,000 doses of COVID-19 vaccines administered this past week alone, and more than 3.5 million doses administered to date across Canada," she said.

Still, less than 10 per cent of Canadians have received at least one dose of a COVID vaccine, Tam noted.

Prime Minister Justin Trudeau said Friday a million doses of the Pfizer-BioNTech vaccine will be delivered every week through the end of May. Canada is also finalizing a deal with the United States to get 1.5 million doses of Oxford-AstraZeneca from its southern neighbour by the end of March. The doses will have a minimum shelf life of 60 days, said Procurement MinisterAnita Anand.

Canada's National Advisory Committee on Immunization updated its recommendations for AstraZeneca this week, saying the vaccine could be administered to those over 65.

In light of the change in recommendations, starting Monday Ontario pharmacies in certain regions will offer the Oxford-AstraZeneca shot by appointment to those 60 and older. They previously only offered that shot to residents aged 60-64.

Ontario residents aged 75 and older will also be able to schedule a COVID-19 vaccine appointment through the provincial booking portal.

The province said more than 50 per cent of Ontario residents aged 80 and older have received at least one vaccine dose.

Quebec, meanwhile, says it intends to vaccinate five million people with a first dose in the next 100 days. The province is looking to enlist up to 50 companies to operate vaccination hubs once its immunization campaign extends to people under 60, Health Minister Christian Dube said.

Quebec administered a daily record 38,459 vaccine doses on Thursday. Roughly 9.8 per cent of the province's population has received at least one dose of a COVID vaccine.

Vaccine eligibility in Manitoba is expanding to people 69 and older and First Nation people 49 and older.Trudeau said the federal government will be deploying the Canadian Armed Forces to Northern Manitoba to help roll out vaccines in First Nations communities that are otherwise hard to reach.

Dr. Jazz Atwal, Manitoba's acting deputy chief public health officer, says health officials are now strongly recommending people get tested for COVID-19 before travelling to First Nations communities.

While progress continues on Canada's vaccine front, Tam noted now is not the time to relax public health guidelines.

Timing of upcoming holidays such as Easter, which is two weeks away, will be cause for caution, Tam said, urging people to "hold on a bit longer" to public health restrictions.

"There is a sense ... that this has been going on for so long that many people are having some difficulties keeping things up. So I do think this is absolutely not the time to let go of those measures."

But as more people become vaccinated, Tam noted public health measures will need to adjust to the changing epidemiological trends.

In addition to the protection offered by vaccines, Tam said the approaching warmer weather will be another welcome barrier to spread. She encouraged people to get outside and avoid the enclosed, crowded spaces with poor ventilation that remain high-risk settings for transmission.

"We got to really give people some of these kind of activities to look forward to," she said.

Deputy Chief Public Health Officer Dr. Howard Njoo said Friday that while the number of older patients requiring hospitalization and ICU admission for COVID illness is decreasing, serious conditions are still being seen in some younger individuals.

He said some parts of the country may need to implement stricter measures to deal with any surges of COVID cases.

"There really is, I think, a caution and a warning that everyone is still at risk, with respect to either coming down with it or transmitting COVID-19 to others," he said. "And so I think we really can't let go."

Alberta is dealing with a sharp rise in the number of COVID-19 cases.

Officials reported 696 new cases on Friday, including 130 variants of concern.

The number of new daily cases has not been that high since the middle of January. The daily case number had fallen to as low as 224 on Feb. 8 but has been above 500 on each of the last three days.

To date, over 922,000 cases of COVID-19, including more than 22,500 deaths have been reported across Canada.

This report by The Canadian Press was first published March 19, 2021.

News from © The Canadian Press, 2021