Canada’s chief public health officer said that the country could face a fourth wave of Covid-19, driven by the Delta variant, by the end of summer if restrictions are eased too quickly and before enough people have been vaccinated.
Dr Theresa Tam said robust vaccination rates have helped reduced hospital admissions and deaths but inoculations must rise further to avoid renewed strain on hospitals and the health-care system.
She urged younger adults to become fully vaccinated as soon as possible, saying they continue to lag among age groups but are associated with the highest rates of disease transmission.
About 6.3 million Canadians have not received a first dose and over five million have not had a second, Dr Tam told a news briefing.
“With just over five weeks until Labour Day in Canada, this time is crucial for building up protection before we gather in schools, colleges, university and workplaces this fall (autumn),” she said.
As of last Saturday, 89% of seniors aged 70 or older had received two doses of Covid-19 vaccines, according to government figures.
But only 46% of Canadians aged 18 to 29 were fully vaccinated, as were 54% of those aged 30 to 39.
Dr Tam said vaccine coverage must be more than 80% in all age groups to establish better protection.
The more infectious delta variant is expected to gain steam among younger unvaccinated people, fuelling a resurgence that could overwhelm health care capacity if personal contacts also rise, she said.
Current Covid-19 case counts have plummeted by 93% since the peak of the third wave, for an average of 640 new infections being reported daily over the past seven days, Dr Tam said.
Deputy chief public health officer Howard Njoo said Canada’s robust vaccination rate means any uptick in infections would likely not correspond to a marked rise in deaths and hospital admissions.
He warned that millions of unvaccinated Canadians “are really at risk of serious outcomes”.