Last winter, we told you about the 2025-2026 respiratory virus season, and how our partners would be closely monitoring vaccine effectiveness (VE) for illnesses like influenza, COVID-19, and respiratory syncytial virus (RSV) in Canada, due in part to the emergence of the influenza A(H3N2) variant, (called subclade K) and the potential impact it would have on the population.
With funding from our Foundation, the Canadian Sentinel Practitioner Surveillance Network (SPSN), led by the BC Centre for Disease Control (BCCDC)’s Dr Danuta Skowronski, published estimates of how well the 2025-2026 influenza vaccine protected against the mismatched subclade K epidemic strain. They showed that the vaccine provided substantial protection, including among older adults who are typically at higher risk of A(H3N2) illness. Vaccination reduced the risk of subclade K illness that was severe enough to require a doctor’s visit by about 40%. Findings were reported through the Global Influenza Vaccine Effectiveness (GIVE) network to the World Health Organization (WHO) in February 2026, informing vaccine strain selection for the norther hemisphere’s upcoming 2026-2027 season.
Since then, the results of VE monitoring are also in for the fall 2025-2026 COVID-19 vaccine. In May 2026, the Canadian SPSN presented their COVID-19 VE findings to the WHO, helping to inform vaccine strain selection for the upcoming 2026-2027 fall COVID-19 immunization campaign.
Examining Respiratory Virus Cases Throughout Canada
The SPSN team analyzed specimens from patients aged 12 years or older that visited their doctors for acute respiratory illness in BC, Ontario, and Quebec between October 2025 and March 2026. They analyzed these specimens using the test-negative design (TND), comparing the proportion vaccinated among patients who sought care and tested positive for COVID-19, with those who sought care for similar symptoms, but tested negative for COVID-19.
Their findings, published in Eurosurveillance and further publicized through Medscape, concluded that vaccinated participants who were on average 9 weeks post-vaccination had about half the risk of COVID-19 compared to unvaccinated people, including among older Canadian adults. SPSN investigators continue to explore ways to improve methods, and precision of findings, with their most recent publication providing new insights into how the circulation of other respiratory viruses, and notably co-infections, may influence COVID-19 VE estimates.
“Given COVID-19 vaccination is targeted to people at elevated risk of severe outcomes, this upstream risk reduction through vaccination even in the context of mismatched lineages is highly meaningful to individual protection.” – Danuta M Skowronski et al. Interim 2025/26 LP.8.1 vaccine effectiveness estimates against COVID-19 from the Canadian Sentinel Practitioner Surveillance Network (SPSN): insights into possible impact of influenza and other respiratory virus co-circulation. Eurosurveillance. 2026; Volume 31 (Issue 18) 07 May 2026
Be a Public Health Hero — Stay Up to Date on Vaccinations!
The annual COVID-19 vaccine is just one of the vaccines recommended by the Government of British Columbia. Immunization schedules, locations to get vaccinated, and vaccination records are all available online through HealthLinkBC.
Vaccinations are one of the most effective public health interventions, and a great example of upstream prevention. Preventing illness, and protecting those around us who are vulnerable to respiratory illness like older Canadians, young children, and those who are immunocompromised, is public health in action. By getting vaccinated, we are all helping to create healthier and safer communities by preventing illness before it can impact someone’s life, and further burden an already overwhelmed healthcare system.
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We have long supported SPSN’s vaccine effectiveness monitoring. As the only charitable foundation in BC actively fundraising for public health initiatives, we know the importance of vaccinations, and the need to continually monitor them, not only to maintain the public trust, but to ensure that we are all armed with the evidence-based information needed to make informed choices about our health. Please donate to help us continue to support these kinds of important initiatives.
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