Canada's flu season is winding down, data shows, but it may be the calm before a COVID storm

Plenty of Canadians caught the flu before the holidays, but the latest federal data suggests the country is now well past the peak of infections. The worry now is holiday gatherings and a return to school and work could help fuel another surge: COVID-19. (Kate Bueckert/CBC - image credit)
Plenty of Canadians caught the flu before the holidays, but the latest federal data suggests the country is now well past the peak of infections. The worry now is holiday gatherings and a return to school and work could help fuel another surge: COVID-19. (Kate Bueckert/CBC - image credit)

While the early months of the year often mark the peak of flu season, Canada is starting 2023 already through the worst — though physicians are now bracing for more hospitalizations ahead, largely due to a potential spike in COVID-19.

The latest figures from multiple provinces show a steady drop in influenza cases in the weeks leading into the new year, while federal data released Friday confirmed flu activity has "declined sharply" from its peak at the end of November.

The weekly percentage of flu tests coming back positive dropped from roughly 13 per cent during the second-last week of December to less than nine per cent in the last week of 2022.

"Flu season's not quite over, but it's declining quickly now," said clinician-scientist Dr. Allison McGeer, a professor at the University of Toronto's Dalla Lana School of Public Health, in a Friday morning interview with CBC News.

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Though it hit hard and fast, putting high numbers of children in hospital last fall, Canada's overall influenza season wound up echoing the experience of countries in the southern hemisphere, such as Australia.

"Which is: Early season, sharp peak, but then coming down pretty quickly," McGeer said. "And a lot of disease in kids — so very hard on pediatric hospitals and people who care for children — but actually pretty quiet for adults."

Over the course of Canada's flu season, more than 1,500 pediatric influenza-associated hospitalizations have been reported, including 183 children ending up in intensive care.

There have also been six influenza-associated pediatric deaths, the latest federal data shows, though prior CBC News reporting suggested the full count among the provinces could be higher, with at least 11 children dying of flu last year across B.C., Alberta, Manitoba and Ontario.

Several physicians told CBC News they're now planning for a potential wave of COVID to start up, while flu is still winding down.

Number of positive influenza tests reported by Canadian laboratories

Concerns remain over COVID, RSV

Federal data showed an uptick in SARS-CoV-2 tests coming back positive across multiple regions by the end of 2022.

Part of the concern also stems from the spread of highly transmissible Omicron subvariant XBB.1.5, which has been reported in multiple Canadian provinces and close to 30 countries abroad.

The subvariant began spreading amid a busy holiday season of socializing and then continued as children returned to school and many adults headed back to work.

Bivalent booster shots are expected to help ward off infection, but protection may be fading for Canadians whose last COVID vaccine dose was several months ago or more, McGeer warned — and anyone who skipped out on the latest updated vaccines could be particularly at risk.

"That combination might mean a significant increase of hospitalizations through January and February," McGeer said, "and I think that's what's worrying people the most at the moment."

WATCH | A tough flu season, now an uptick in COVID cases:

COVID will continue making the situation in hospitals difficult, all while circulation of respiratory syncytial virus (RSV) also remains high, which could continue bringing more sick children into pediatric hospitals, noted Dr. Srinivas Murthy, a clinical associate professor with University of British Columbia's faculty of medicine.

"As the strain has been visible over the health system for the last couple of months, I think our capacity to respond remains a challenge," he said.

"We're still seeing much higher levels of RSV-related admissions than we have before," echoed Dr. Nisha Thampi, medical director of infection prevention and control at the Children's Hospital of Eastern Ontario (CHEO).

"I don't think we're out of the woods yet."