Why the acceleration in new COVID-19 cases in Canada is concerning

The steady increase in new cases of COVID-19 in Canada's most populated provinces is a concerning trend, according to the country's chief public health officer, as hospitals work to keep intensive care admissions manageable.

Dr. Theresa Tam said in a statement Monday that an average of 618 new cases have been reported daily in the last seven days, particularly in Quebec, Ontario, Alberta and British Columbia.

"We're watching not just the numbers but the speed of ramp up and how widespread the cases are," Tam said in an interview with CBC Radio's The Current.

"If there's a rapid rise over a short period of time, confined to a very specific location, what you're worried about is stressing the public health system and the health system in those areas."

Hospital and ICU admissions are a sign of concern since older groups generally have more serious outcomes from COVID-19, although people of any age can be affected and transmit the infection, she said. 

WATCH | Early resurgence a concern, infectious disease specialist says:

Dr. Isaac Bogoch calls the upward trend in COVID-19 cases 'worrisome'

4 years ago

Duration 0:36

'I was really expecting to see more of a rise like this in October but it's real and it's happening now,' said Dr. Isaac Bogoch, an infectious disease specialist.

Tam said her public health counterparts say the situation is currently "manageable." But their jobs become more difficult if people aren't doing their part to minimize their numbers of contacts and exposures should a case occur.

Dr. Kevin Smith, president and CEO of Toronto's University Health Network, has said he's "worried" because the number of patients with COVID-19 in intensive care has increased after some weeks of having no one hospitalized with the disease.

Cases are doubling in Canada's largest city every six to eight days, Smith told CBC Radio's Metro Morning. He called on people to "get serious" about physical distancing, masking, handwashing and limiting gatherings.

Epidemiologists look at the effective reproductive number of COVID-19, which indicates how many other people an infected person will pass the virus onto, on average. Public health experts like to see the value significantly below one so cases don't multiply out of control.

Raywat Deonandan, an epidemiologist and associate professor at the University of Ottawa, said Canada's current effective reproductive number, or R value, is above one, which by definition is exponential growth.

"It means that we're in some dangerous territory," Deonandan said. "I don't think it'll get as bad as it was at the peak of this, but it will get bad."

The Public Health Agency of Canada said in its latest weekly report on Sept. 11 that the effective reproductive number is 1.05.

Since March, physical distancing protocols, mask-wearing procedures and treatments have improved the chances of surviving, he said.

"If we can delay the gratification of the need for intense socializing for several months, our reward will be less suffering, less death and a more open society."