Is it too late to get the flu shot? We're answering your influenza questions

Should you acquire a flu crack if it’s non a hone match for this year’s strains? Experts say yes

What science says about this year's flu shot

Uptick in child flu cases putting pressure on Quebec pediatric hospitals

Saskatchewan hit hard by influenza as data shows 80% unvaccinated

CHEO asking Ottawa doctors to work extra hours as flu visits surge

B.C. Centre for Disease Control reports increase in flu cases among children

Should you get a flu shot if it’s not a perfect match for this year’s strains? Experts say yes

No one has a crystal ball, but Saxinger said there’s already clear evidence showing this year’s flu season is one of the worst in many years.

In Alberta, she said, data shows influenza cases in hospitals for 2025 are the highest they’ve been in the last decade, and the season’s still far from over.

While many experts do say Canada’s flu season could be close to peaking, Saxinger cautioned against letting out a sigh of relief just yet.

“There's kind of a false comfort in saying it's peaked, because everything that goes up has to come down,” she said. “And so there's at least as many cases on the downside as there were on the upside.”

That means there’s going to be very intense flu transmission in the community for quite a while, “and it’s during a time where people are shifting geography and visiting with people they don't always visit with,” Saxinger noted.

“There’s usually a tipping point where there's enough spread in the community that it's hitting people who are more high risk, and you see the influx coming into hospital. So there's a little time lag,” Saxinger explained.

Official data is always a snapshot of the past, and doesn’t always keep up with the rapid expansion of flu activity in the community. What’s happening in hospitals right now, Saxinger said, is that more patients are now coming in with severe influenza and its complications.

“What I was seeing a lot last week was secondary infections, so like a bacterial pneumonia or sepsis on top of influenza,” she said.

The flood of patients was fast and furious this year, and in Saxinger’s hospital in Alberta, she said the wards are “full and overflowing,” leading to hallway beds and a “miserable experience” for both the patients and staff.

“It really was a very sharp uptick this year in terms of going from leading indicators [to cases] going up to now… it seemed like it was a pretty brief time period.”

When it comes to influenza, data doesn’t tell the whole story. It takes time for infections to progress enough that people end up in hospital, for test results to come in and for government officials to wade through the numbers and share them publicly.

So what’s happening in real-time at hospitals, and just how bad is this year’s flu season on the ground? We spoke to Dr. Lynora Saxinger, an infectious diseases physician and professor at the University of Alberta.

Absolutely, says McGeer.

For one thing, we don't know exactly where we are in the flu season, she said. "We've probably got at least half of it left to go. So, OK, it's only going to protect you for a third of the season — because it takes a while to ramp up to get protection — but it's still worth it."

And, if you weren't tested at a hospital, there's also no way of knowing for sure whether or not you caught influenza or another respiratory bug.

"People are remarkably attached to thinking that they know which virus it is when they get sick," McGeer said. "But the evidence is that you don't."

"The thing about influenza is it feels like it's not dangerous, but it's bloody dangerous," said McGeer. "Which gets us back to the thing about flu vaccines: always, and at any time of year, they're way less than perfect. They're just much better than nothing, right?"

So, sure, the flu shot might be mismatched to this year's dominant form of H3N2, but the good news is it still appears to ward off serious illness — and protects against more than one type of influenza. (Influenza B, for instance, tends to surge later in the season.)

According to the World Health Organization, the latest available vaccine effectiveness estimates show the current flu shot is up to 75 per cent effective at preventing hospital visits in children aged two to 17 years, and 30 to 40 per cent effective in adults.

"The challenge with flu — particularly H3N2, but flu in general — is that it just mutates really quickly, and you need time to make vaccines," McGeer said.

While the world witnessed the rapid development of COVID-19 shots during the pandemic, chasing the evolution of seasonal flu requires ongoing work, and even months-long turnarounds can't always keep up with the virus's changes.

In the case of this year's H3N2 strain, the first samples showing this new subtype were identified in April, while its spread didn’t really start to accelerate until sometime in June, McGeer noted.

Let's turn to some of your questions.

We took some of the top questions to clinician-scientist Dr. Allison McGeer, one of Canada's top infectious disease specialists and a longtime researcher on the epidemiology of influenza.

The PHAC is also calling on Canadians to take precautions, particularly as the holiday season is in full swing.

“This time of year, when we are all gathering for the holidays with our loved ones, including young and old, it is an important moment for everyone to take care of each other,” said Dr. Natasha Crowcroft, Canada’s acting chief public health officer, in a statement.

“The best way to protect your family, friends and yourself from spreading influenza is to make sure everyone is vaccinated. Taking precautions — vaccination, hand hygiene and early care when symptoms appear — can significantly reduce illness and save lives.”

Here are a few key trends from the latest federal data:

The latest data from the Public Health Agency of Canada (PHAC) released Friday shows the number of countrywide flu tests coming back positive is now at nearly 28 per cent, marking a jump of eight percentage points from last week’s update.

There’s also a major jump in the number of weekly flu outbreaks, with 186 reported, up from 91 in last week’s data.

Since the start of flu season, influenza activity has been “increasing sharply and simultaneously across most provinces and territories,” PHAC said in a statement, with evidence suggesting “influenza is circulating widely in the community.”

Federal officials also warned that hospitalizations linked to flu are expected to spike in the weeks ahead.

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