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Some emergency departments across Canada report that the rapid spread of influenza has contributed to overcrowding, as some children and adults face long-lasting fevers, with the latest federal report showing a slight declining picture of flu activity across the country.
For the week ending Dec. 27, 2025, 33.3 per cent of tests were positive, the highest value recorded in the past three seasons, the Public Health Agency of Canada reported. On Friday, a federal snapshot pointed to flu positivity at 27.1 per cent as of Jan. 3.
Parts of British Columbia, Alberta, Ontario, Quebec and Prince Edward Island reported widespread activity for influenza.
Influenza A and B cause seasonal epidemics, with influenza A classified into subtypes. The current spike is driven by the H3N2 subclade, called K, with mutations that don’t appear to cause more severe disease, according to the World Health Organization.
But one of several components may be mismatched from those targeted in this year’s flu shot, which infectious disease physicians and public health officials stress still protects against other flu subtypes and, importantly, offers protection against severe outcomes like hospitalization admissions in people of all ages, in a U.K.-based study published in the journal Eurosurveillance.
The early and intense rise of flu this season contributed to a surge at Toronto’s North York General Hospital over the past few weeks, said Dr. Kevin Wasko, the hospital’s chief of emergency medicine.
Public Health Ontario reported flu activity declined over the past two weeks, “indicating the peak in activity occurred during the week of December 14-20,” 2025, according to the province’s dashboard.
“We’re now feeling the impact of a lot of our admissions that resulted from influenza A on our wards,” Wasko said. “Our hospital is full and so we’re experiencing at the same time a lot of admitted patients remaining in our emergency department waiting to receive a bed upstairs.”
On Thursday, dozens of people there were waiting to be triaged or admitted and CBC News saw more than a handful of patients lying on stretchers in a hallway.
“It has put a lot of strain on the system,” Wasko said. “But if you need our services, no one should ever hesitate.”
If someone can’t breathe, or they can’t keep anything down, or they’re so weak that they can’t carry out their daily activities, they should come, Wasko added. About 90 per cent of patients are seen within three hours of presenting, he said, a rate they hope to maintain over the season.
In southwestern Ontario, the Erie Shores emergency department had shorter waits than North York, but a similar trend of more children being impacted than in previous years.
“We are seeing a higher number of admissions for influenza type A and we’ve been seeing more severity regarding pediatric patients,” said Dr. Braedon Hendy, chief of emergency medicine at Erie Shores Healthcare in Leamington, about 50 kilometres east of Windsor, Ont.
New Brunswick Health Minister John Dornan says the increase in flu cases this year is the result of fewer people getting vaccinated. He says the problem is causing increases in emergency department visits.
Influenza affects people of all ages with a range of severity of symptoms of fever, cough, sometimes congestion and fatigue.
With subclade K, “we’re seeing kids with fevers for longer time periods, so maybe five to seven days, maybe more people having GI symptoms,” such as diarrhea, said Mark McKelvie, a regional medical officer of health with NL Health Services in Newfoundland.
Pediatric infectious disease specialists have noted that most children simply haven’t been exposed to the H3N2 strain, as it hasn’t been the predominant strain for a few seasons.
In Ontario, the clinical picture of influenza matches what scientists are seeing in wastewater testing, with subclade K dominating, said Trevor Charles, a professor of microbiology at the University of Waterloo who is conducting work for York Region at his lab.
The newest wastewater data will confirm whether the downward trend that Ontario has reported so far holds after people gathered over the holidays, Charles said.
“Some of the late-December sampling is indicating it might be coming down, but we need to see what the newest data shows in order to confirm that,” Charles said.
