Canada is experiencing an early rise in flu cases. Is a “tidal wave” of infection coming?

Canada is on track to face its first full flu season in several years – a season that is starting earlier than usual, when the country’s health system is already struggling with respiratory infections like COVID-19. and RSV.

It’s unclear how the coming months will unfold, including what level of pressure severe flu infections will put on overwhelmed hospitals, and how this year‘s list of viruses will interact now that SARS-CoV-2 is firmly in the picture. The mixture.

But what is clear is that there is already a sharp rise in recent infections and that a “tidal wave” of cases is likely, said infectious disease physician Dr Sameer Elsayed and medical microbiologist in London, Ont, and professor at Western University.

“We’re going to have a big flu season, I think, this year.”

On a national level, influenza activity “increased sharply” and crossed the seasonal threshold of 5% of samples coming back positive at the end of October. If these trends continue, the federal government will declare the start of an influenza epidemic in Canada in its next update, scheduled for November 14.

Ontario has already surpassed that benchmark, with about 10% of recent tests coming back positive for this year’s dominant strain of influenza A.

In Public Health Ontario’s latest update of November 4the province said the flu season started “more than a month earlier than what is typically seen in pre-pandemic seasons.”

The early start comes as children’s hospitals across the province are already overflowing with children with illnesses such as respiratory syncytial virus, or RSV, and as positive test results for COVID-19 are back on the rise, recently reaching 17%.

“Over the next few months, Ontario will likely face the triple threat of respiratory disease,” said Dr. Rose Zacharias, president of the Ontario Medical Association, an advocacy group for physicians. at a press conference on Wednesday.

Alberta also began to experience a spike in influenza A cases. end of Octoberalongside the circulation of other pathogens, and BC public health officials are also monitoring a continued increase in positive samples.

“Right now we’re seeing the flu spread and samples coming in from long-term care facilities, children’s hospitals and adult hospitals,” said medical microbiologist Dr Linda Hoang, associate director and program head. from the bacteriology and mycology laboratory at the BC Center for Disease Control.


Hints from the southern hemisphere

The progression of the flu season in Canada from here may mirror, to some extent, what countries in the southern hemisphere experienced earlier this year.

In Chile, where the 2022 flu season has passed, influenza A began circulating “months earlier” than during pre-pandemic flu seasons, according to a recent report published by the United States Centers for Disease Control. (The United States is also experiencing an early start, southern states experiencing the highest surges.)

Chilean officials reported more than 1,000 hospitalizations during the season. That’s higher than during the COVID pandemic when public health restrictions and other factors kept the flu at bay for more than a year, but lower than during recent pre-pandemic flu seasons. The country’s flu shots also cut the risk of hospitalization by nearly half.

Data on lab-confirmed flu cases in Australia this year also show that the country has seen both an early start and end to its flu season, and a far higher level of infections than any of the previous five years.

But the clinical severity of the 2022 flu season – referring to the total number of deaths and the proportion of patients admitted to intensive care – has been rated “low” by the Australian government.

WATCH | Ontario doctors warn of a ‘triple threat’ respiratory season:

Concerns grow over triple threat of respiratory disease surge

The Ontario Medical Association is urging people to wear masks indoors and get their flu and COVID-19 shots amid growing concern that a spike in flu cases could overwhelm a system healthcare that is already seeing an influx of RSV and COVID patients.

So what do these trends portend for Canada in the months ahead?

Alyson Kelvin, a virologist and researcher at the Vaccine and Infectious Disease Organization at the University of Saskatchewan, said it’s possible our flu season could also “peak and decline” earlier as well.

But she pointed out that the combination of influenza and other respiratory viruses, including the first circulation of COVID during the winter months without any public health restrictions, makes the period ahead particularly difficult to predict.

It is possible that the early start of the flu season in the southern hemisphere, now spilling over to countries further north, suggests that the virus is moving through circulation on the heels of other waves of infections.

“We could see a further increase in COVID-19 cases, possibly in early January,” Kelvin said. “But it could also just be the aftermath of not having seen the flu in the past two years; I really don’t know. And I’ll be watching the numbers to see a clearer pattern over the next two years.”

Is it time for masks again?

Hospital teams fear that different waves of viral infections could mean months of strain on Canada’s health care system, whether or not flu cases alone account for high levels of hospitalizations this season.

“It’s only November,” Dr. Fahad Razak, an internist at St. Michael’s Hospital in Toronto, said in an interview on CBC News Network.

“Respiratory virus season, including influenza and RSV, but of course COVID as well, is expected to peak in the coming months, so we haven’t seen, probably, how much worse it’s going to get.”

The coming months could be “very, very difficult”, he added, given the already long wait times for access to care in many overwhelmed and understaffed hospitals across the country.

Given these concerns, a growing choir of doctors now call for a back to wearing a mask indoors to mitigate the spread of viral infections.

WATCH | Toronto doctor calls for return of mask mandates:

It’s time to bring back the mask mandate, says a Toronto doctor

Dr. Fahad Razak, an internist at St. Michael’s Hospital, says the triple threat posed by COVID-19, RSV and influenza should be addressed through public health measures like mask mandates.

“If added to the other layers of protection, including vaccination, it could actually make a difference in terms of mitigating the surge so that hospitals can cope a little better,” said the director of the Public Health of Canada, Dr. Theresa Tam. said at a press conference on Thursday.

A study published this week in the New England Journal of Medicine offered more evidence to suggest that masks can help mitigate transmission of the virus. The peer-reviewed research, which focused on Boston school districts, found that lifting masking requirements was associated with about 45 additional COVID cases per 1,000 students and staff in the months after the end. of a statewide policy.

Masks are a blunt and flawed tool, Razak said, but one that has also helped keep the flu at bay in Canada for much of the pandemic.

The 2020 flu season ended abruptly after a series of public health restrictions were put in place to combat COVID, and there was also no evidence of community circulation of the flu the following season.

Generally, the flu is thought to kill thousands Canadians each year, while COVID is currently killing hundreds every week.

Canadians encouraged to get flu and COVID vaccines

Getting a vaccine to protect against both is paramount this fall, several medical experts pointed out in recent interviews with CBC News.

It is even safe to get both a COVID reminder and an annual flu vaccine at the same appointment, according to the National Advisory Committee on Immunization of Canada.

Kelvin, who has long studied the flu, said Canadians should always take the threat of the flu seriously.

The added fear now, she said, is that it comes back while there is another respiratory virus – SARS-CoV-2 – now in the mix.

“It will add to the increase in serious illness cases,” she said. “And that’s what I want to be careful about – that we’re doing everything we can to reduce the transmission of respiratory viruses in the community.”

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