A push to shift efforts toward fully vaccinating the population gained steam Friday with Canada's advisory panel on vaccines urging second doses "as soon as possible," and federal health officials hinging summer reopening plans and any eased travel rules on immunizations and ongoing public health measures.

Health Minister Patty Hajdu and Chief Public Health Officer Dr. Theresa Tam touted "layers of protection" as key to emerging from a formidable third wave that new modelling suggests is continuing to wane, urging caution as some provinces eye reopenings.

That caution extended to Ottawa's consideration of an expert report that recommends Ottawa scrap the hotel quarantine requirement for air travellers, with Tam saying the topic is under "active discussion" and that officials will address it in the near future.

Canada's top doctor was similarly careful in her assessment of Quebec's decision to lift curfews and reopen outdoor spaces such as restaurant patios Friday, allowing the moves were "not unreasonable" in light of regional epidemiology.

However, she warned that hasty reopenings could lead to "pockets of resurgences" among under-immunized populations.

"We've had a few experiences in the past that has led us to wanting to be more precautionary," said Tam.

The National Advisory Committee on Immunization recommended Friday that Canada turn toward the ultimate goal of fully immunizing the population, now that supplies of COVID-19 shots are increasing.

The panel said those at highest risk of dying or becoming severely ill should be prioritized for second shots, either after or alongside first doses for anyone else who is eligible for a vaccine.

"The 16-week interval was the upper limit and provinces and territories should aim to start administering second doses as quickly as regional logistics allows it," NACI chairwoman Dr. Caroline Quach said in a statement Friday.

"First doses have been a highly effective starting point from a population immunity perspective, and we now need to move toward our second doses to provide more complete long-term protection."

Infectious disease expert Dr. Sumon Chakrabarti welcomed NACI’s advice to aggressively deliver second doses, especially to seniors and others at higher risk of severe infection.

But he added that all Canadians should strive to become fully vaccinated "as fast as possible" because variants of concern including B. 1.617 — the strain first identified in India — could threaten to undo the country’s progress.

"A three-week interval for Pfizer works really well. A three-month interval might work even better, but right now that doesn't really matter,” said the Mississauga, Ont. physician.

"We are seeing some early evidence that B. 1.617 might have a little bit less efficacy with one dose of a vaccine."

Meanwhile, new national modelling suggested the COVID-19 crisis has taken a turn for the better over the past month.

Tam said more than 22 million vaccine doses have been administered across the country and that Canada has crested the third wave.

Average case counts are now less than half of what they were during the peak of the third wave in mid-April, with fewer than 3,400 cases reported daily over the past seven days, said Tam.

The number of people experiencing severe or critical illness is also decreasing, though at a slower pace, she added, stressing the need to maintain many public health measures.

Federal health authorities were circumspect about whether the government will heed an expert panel's recommendation that Canada drop a requirement for air travellers to quarantine for three days in a government-approved hotel.

Global vaccination coverage is not very high at the moment, Tam noted, and officials must consider domestic levels of disease and immunity.

Hajdu added that the issue of international travel "is a delicate and contentious one" and any changes to border measures demand discussion with provincial counterparts. 

"We want to make sure that we continue to protect Canadians' risk of importation of virus no matter what measures we have at the border," Hajdu said.

Procurement Minister Anita Anand said Canada has confirmed shipments of 15 million more doses of COVID-19 vaccines from three suppliers, which she said means every eligible Canadian will have access to a second dose by the end of the summer.

Anand said 2.4 million doses of Pfizer-BioNTech will arrive each week over five weeks in June and nine million more will arrive in July.

Moderna is set to send 500,000 doses in two shipments early next month, and 1.5 million more doses are scheduled to arrive the week of June 14.

Also on Friday, Ontario became the latest province to fast-track its second-dose schedule.

Shortened dose intervals will be offered first to those aged 80 and older next week, followed by those 70 and older in mid-June. Residents will then become eligible for faster second doses based on when they received their first shot.

The province also reported 1,273 new cases of COVID-19 on Friday and 14 more deaths linked to the virus. There were 1,023 people in hospital, including 645 in intensive care and 458 on ventilators.

Health officials in Manitoba, however, say disruptions in the supply chain of COVID-19 vaccines means that a major milestone has been pushed back.

Johanu Botha, co-lead of the province's vaccine implementation task force, said Manitoba is receiving significantly fewer doses of the Moderna vaccine than expected and deliveries have been delayed.

That means the province likely won't meet its target of delivering first doses to 70 per cent of people aged 12 and up by June 9, but will probably hit that benchmark at the end of next month, Botha said.

The province's COVID-19 surge continued to strain the health-care system, with officials reporting 493 new cases, 312 hospitalizations and 69 patients in intensive care. Another 26 Manitobans were in intensive care in other provinces.

Alberta, where officials announced more than 60 per cent of eligible residents have received at least one dose of vaccine, said more health restrictions will be loosened June 10 if hospitalization rates continue falling. The province reported 512 new cases and there were 517 in hospital.

Quebec embarked on the first stage of its reopening plan Friday, permitting dining on restaurant patios and backyard gatherings. Quebec's 9:30 p.m. curfew — which had been in effect in most of the province since Jan. 9. — was also lifted.

The province's public health institute said Quebec could avoid another wave of novel coronavirus if people follow health orders.

Quebec reported 419 new cases of COVID-19 and four more deaths related to the virus. There were 385 hospitalizations and 91 people in intensive care.

Nova Scotia released a four-stage plan to emerge from its lockdown restrictions Friday, with Premier Iain Rankin proclaiming the province's COVID-19 wave was being "crushed in almost record time."

Most changes will begin Wednesday, allowing businesses to open further, outdoor visits to occur at long-term care facilities and increased outdoor gathering limits. In-person classes will also resume Wednesday at schools outside the Halifax Regional Municipality and Sydney.

Nova Scotia reported 40 new COVID-19 cases and one death.

In B.C., there were 317 new cases of COVID-19, far off the high of more than 1,300 in March when restrictions were tightened. 

— with files from Melissa Couto Zuber

This report by The Canadian Press was first published May 28, 2021.

Adina Bresge, The Canadian Press