Alberta's flu death toll hits 15-year high, sparking calls for better immunization outreach

Alberta is emerging from its deadliest flu season in 15 years.

Provincial data shows 167 people died of influenza during the 2023-24 flu season, eclipsing all other seasons dating back to 2009.

This season's death toll more than tripled the 2018-19 season total and nearly doubled the prior year. Last season, which was the previous high, saw 123 influenza deaths.

The influenza death rate (the number of deaths for every 100,000 people) is also the worst in years.

"That is genuinely a very high death toll in a flu season. It really does stick out compared to other years," said Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta.

Severe cases started surging very early and vaccine uptake was sluggish from the start, she said.

"We had a combination of a really aggressive influenza season start and then kind of a relatively slow start to vaccine uptake, including in the highest-risk group, which are those who are over 75. So I think that was some really bad timing."

The main driver of this season was H1N1, a type of influenza A, that can hit young and middle-aged adults hard but ultimately remains most deadly for older people, according to Saxinger.

"Coupled with the fact that most people didn't get influenza vaccination as much as usual over the pandemic period, I think that people's immune systems were a little bit caught unawares by the H1N1 strain that was coming through. It is in all the vaccines," she said.

Alberta Health said a variety of factors can influence the severity of an influenza season, including the dominant strain.

It also said flu death surveillance has increased since the COVID-19 pandemic began. Now all deaths that occur within 60 days of a lab-confirmed influenza case are followed up in a systematic way.

Public health also began tracking community deaths, in addition to hospital deaths, during the 2020-21 season. However community deaths account for a small proportion of the totals — between five and seven deaths in each of the last three seasons.

Flu death data prior to 2009 is not publicly available and does not appear to have been tracked in the same way.

Low vaccination rates

Alberta's respiratory virus dashboard shows 25.1 per cent of Albertans received their flu shot this season, the lowest vaccination rate in the last decade.

"That is our single best tool at preventing loss of life and preventing hospitalizations. And it's clearly a tool we did not use to its maximum capacity this year," said Craig Jenne, a professor in the department of microbiology, immunology and infectious diseases at the U of C.

"As a result we see unfortunately a record loss of life in the province."

This death toll, according to Jenne, should serve as a wake-up call for Alberta.

"I think it's data we're going to have to take a good hard look at once the flu season is over and figure out how we can better prepare ourselves or avoid this scenario in the coming seasons," he said.

"Part of that may be a hard look at our influenza campaign. We do know that flu shot numbers were down this year compared to really the last decade or more."

Alberta's respiratory virus dashboard shows 25.1 per cent of Albertans received their flu shot this season, the lowest vaccination rate in the last decade. (Doug Ives/The Canadian Press)

According to Saxinger, that preparation should include getting shots in arms earlier.

"This was really going up very aggressively in October, and we didn't even have vaccine supply when things were really starting to warm up," she said.

"We have to make sure the whole system is primed to deploy vaccines as quickly as they're available, and really try to focus on the outreach to high-risk groups and try to start socializing the idea about the fall flu shot again."

Alberta Health said that, while overall vaccination rates have declined in recent years, immunization coverage for seniors, who have a higher risk of severe illness and death, remained relatively stable.

Provincial data shows 59.4 per cent of Albertans age 65 and older received their flu shot this season.

Albertans over the age of 60 accounted for 131 of the 167 deaths this season.

Two children, between the ages of one and nine, also died.