Doctors urge vaccination as influenza upswing hits Alberta

Flu positivity rates, hospitalizations rise amid concerns about mismatched variant.

Jennifer Lee, CBC News Calgary, Nov 24, 2025

Influenza is starting to surge in Alberta, and hospitals are getting busier as doctors brace for what could be an intense few months ahead.

The province’s flu positivity rate more than tripled to 11.5 per cent during the second week of November, from 3.4 per cent two weeks earlier.

“It’s a pretty solid upswing. The season has started,” said Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta Hospital.

“We have had an uptick in the number of people admitted to hospital. And, as usually happens, it seems to start in Calgary first.”

The flu has been responsible for 251 hospitalizations, including 158 in the Calgary zone alone, so far this season. Seventeen Albertans have been admitted to the ICU and six people have died.

The latest data shows 74 people were in hospital due to influenza as of Nov. 15, a nearly three-fold increase in two weeks.

The emergency department at the Alberta Children’s Hospital has been increasingly busy, said Dr. Stephen Freedman, a professor of pediatrics and emergency medicine at the University of Calgary’s Cumming School of Medicine.

According to Freedman, there was a lull during the recent teachers’ strike followed by a rapid uptick once kids were back in school.

“Most of the children who seem to be sickest right now have either influenza or RSV,” he said.

“It is typical of what we tend to see. And we’re really just trying to figure out what the surge is going to be like, how much that’s going to strain our system, and what the capacity demands are going to be as we move forward into the winter.”

Alberta’s flu upswing is currently driven by two types of influenza A: H3N2 and H1N1.

H3N2, which can cause more severe illness, now accounts for more than half of the lab-confirmed cases this season.

Worrying signs

The surge is playing out amid worrying international flu trends, according to Angela Rasmussen, a virologist at the University of Saskatchewan. Japan is experiencing an early and harsh flu season, she noted. Influenza is also hitting early in the United Kingdom.

What has complicated matters is that a new offshoot of H3N2 (known as subclade K) emerged after this season’s North American flu vaccines were formulated — and experts are worried it may not be well matched to the vaccine.

“It looks like this variant is kind of gaining momentum. And it’s possible that this variant does have some type of transmission or fitness advantage over the old variants of H3N2,” said Rasmussen.

National data shows most of the Canadian H3N2 cases sequenced are the new variant.

An official with Alberta’s Primary and Preventative Health Services said hospital admissions and positivity rates are so far similar to previous years.

“It’s still too early to determine what kind of influenza season Alberta will experience,” an emailed statement said.

Saxinger agrees predictions are difficult, in part because it’s unusual to see both H3N2 and H1N1 strains circulating at the same time.

“We always worry with an H3N2 season that you might see more severe disease in older people… and I think that remains a real risk,” she said.

All this comes after several seasons of dropping immunization rates in Alberta, along with the highest number of flu deaths in recent memory.

“Last year was a record flu season for Alberta, for all of Canada, for all of the United States. And one of my biggest concerns is that this year we’re going to outdo that potentially,” said Rasmussen.

Get the flu shot, experts urge

All three experts agree vaccination remains key.

“The real benefit of the flu shot is that if you do get infected, it keeps you from getting really, really sick. It keeps you out of the hospital,” said Rasumussen.

Freedman is worried people might be discouraged from getting the vaccine when they hear about a potential mismatch.

That’s the last thing he wants to see.

“The vaccine does seem to show good effectiveness, particularly in children, where data from the UK… showed that the vaccine was 70 to 75 per cent effective at reducing emergency department visits by children,” he said.

In an emailed statement, the Ministry of Primary and Preventative Health Services said, “Even with partial mismatch, immunization remains the best protection.”

Avian flu, too

Adding to the uncertainty is a recent rise of avian influenza outbreaks on farms in Canada and the U.S., said Rasmussen.

With more bugs circulating, there is a higher chance that two influenza viruses could infect the same person at the same time. When that happens, mixing (or reassortment) can occur, where the viruses essentially swap genetic material, creating a new virus.

That has the potential to lead to a pandemic strain, Rasmussen said, if the virus acquires the ability to transmit well between humans.

“Our continent is essentially full of bird flu, and now there’s going to be a lot of human seasonal flu in the mix as well,” said Rasmussen.

“It means that the risk is elevated. And so that’s what causes me and a lot of my colleagues who think about this a lot to lose sleep at night.”

Jennifer Lee Reporter

Jennifer Lee is a Senior Reporter for CBC News based in Calgary. She covers health stories for CBC’s web, radio and video platforms. If you have a story to share, let her know.

Source CBC News Calgary