Evolving H3N2 strain may not be well-matched to this year’s flu vaccine: report
As influenza cases begin to climb across Canada, HR professionals are being urged to prepare for what could be the most severe flu season in years.
Medical experts are sounding the alarm over the global spread of an evolving H3N2 strain that may not be well-matched to this year’s flu vaccine, according to a CBC report.
Recent federal data reveal that approximately two per cent of influenza tests in Canada came back positive last week — a noticeable increase, though still below the five per cent threshold that signals a national epidemic, the publication notes.
The Southern Hemisphere has experienced record-breaking flu case counts for the second year in a row, with Australia reporting over 410,000 lab-confirmed cases. The United Kingdom and parts of Asia have also seen early and intense flu seasons, with the U.K. facing cases three times higher than last year and Japan declaring a flu epidemic that has led to widespread school closures.
“It's the second year in a row where they've had above-average influenza detections in the Southern Hemisphere,” says Jesse Papenburg, a paediatric infectious disease specialist at the Montreal Children’s Hospital and the McGill University Health Centre, in the report.
“In terms of the number of cases, last year was probably the worst influenza season Canada had had in a decade, and it seems like that could occur again this year in terms of severity of disease.”
The primary concern this season is the rapid evolution of the H3N2 strain of influenza A. Danuta Skowronski, epidemiology lead for influenza and emerging respiratory pathogens at the B.C. Centre for Disease Control, told CBC that recent mutations in H3N2 may have created a significant mismatch with the current vaccine.
“The difference between the circulating H3N2 virus and what's in the vaccine is quite a bit different, actually, and that's no one's fault. It's just the nature of influenza. It's a very changeable virus,” Skowronski explained.
While this year’s flu shot still targets two influenza A strains (including H3N2) and one influenza B strain, the potential mismatch means vaccine effectiveness could be reduced. For employers, this highlights the importance of layered prevention strategies — vaccination remains critical, but additional workplace hygiene and sick leave policies will be essential.
Influenza is a serious disease that causes thousands of deaths and hospitalisations across Canada each year, according to a previous report.
How can employers protect workers from the flu?
“Employers can implement a variety of health and hygiene best practices to help prevent the spread of these viruses,” says Michelle Ann Zoleta, health & safety team manager.
Here are some of the most effective flu prevention measures you can include in your workplace, she says:
- Encourage employees to get the flu vaccine.
- Promote workplace hygiene practices.
- Maintain clean work environments.
- Implement flexible sick leave policies.
- Create an emergency response plan.
- Encourage healthy habits.
- Promote a supportive environment.
- Provide self-monitoring resources and telehealth.
- Lead by example.
“Every year, thousands of Canadians become infected with the flu or other viral illnesses. For Canadian employers, the spread of these illnesses can bring significant challenges to the workplace, ranging from increased staff absences and reduced productivity to the rising costs of health benefits,” says Zoleta.
“To avoid major disruptions to business operations, employers should take a proactive approach to flu and viral infection prevention. By implementing proper hygiene practices and health measures, you can stop the spread of these viruses in the workplace, ensure employees stay healthy and avoid unnecessary service interruptions.”
In 2024, the British Columbia government started a new vaccine registry.
