A powerful wave of influenza is sweeping across Canada, straining emergency departments and driving a rapid increase in hospitalizations. At the heart of this early and intense season is a mutated strain of influenza A H3N2, informally called the "super flu," which has become the dominant virus circulating.
An Unpleasant Firsthand Experience and a National Surge
The severity of this flu season is not just a statistic for Matthew Miller, a Canada Research Chair in viral pandemics at McMaster University. He recently endured a confirmed case of influenza A just days after abdominal surgery. "Coughing after having abdominal surgery is no good to begin with. On top of that, I was really non-functional," Miller shared, describing fever, muscle aches, and debilitating fatigue.
While his rapid test only confirmed influenza A, it is highly likely he contracted the prevalent mutated subclade, known as K. This variant is fueling a national health alert. For the week ending December 13, the Public Health Agency of Canada reported flu activity as "high and increasing," with 27.7 percent of tests coming back positive. This positivity rate matches the highest levels seen in the past three seasons.
Doctors nationwide are reporting emergency rooms "rammed with flu cases," with hospitalization rates climbing fastest among adults 65 and older and children four years and under.
Why This Season Stands Out
Dr. Jesse Papenburg, a pediatric infectious diseases specialist at the Montreal Children's Hospital, points to several factors making this flu season remarkable. "It started relatively early... and this one is very sharp. Rates have been rising quite precipitously these past few weeks," he explained.
One of the most striking features is the virus's impact on school-aged children. In Quebec and Ontario, roughly 60 percent of flu tests in this age group are currently positive, a figure significantly higher than the typical peak range of 25 to 40 percent. Dr. Papenburg anticipates the season will peak around New Year's Day.
Matthew Miller adds that this year has posed "unique challenges," including the early start and a mismatch between the circulating strains and this year's flu vaccine formulation.
Vaccine Protection and Key Takeaways
Despite the strain mismatch, vaccination remains a critical layer of defense, especially for children. Dr. Papenburg cites a UK study from this year indicating that the flu shot was 60 to 70 percent effective in children at reducing the risk of emergency department visits or hospitalizations.
The current situation underscores the unpredictable nature of influenza. The confluence of an early, aggressive start, a dominant mutated strain, and high attack rates in young people is creating significant pressure on the healthcare system. Public health officials continue to emphasize the importance of vaccination, hand hygiene, and staying home when sick to slow the spread as Canada approaches the expected peak of this severe flu season.
