Latest Influenza Surveillance Report Highlights Key Trends
Recent data from the Canadian Respiratory Virus Surveillance Report indicates a sustained increase in influenza activity nationwide. Notably, the percentage of positive influenza tests has reached 26.9%, the highest recorded level since the 2020-21 season. This trend is particularly affecting individuals aged 65 and older, who are experiencing the highest rates of influenza detections and hospitalizations.
For the surveillance week ending February 15, 2025, the national influenza positivity rate was recorded at 26.91%, reflecting a continued upward trajectory. Provincial data reveals significant variations, with Quebec (34.15%), Prince Edward Island (34.5%), and British Columbia (32.22%) reporting notably elevated detection rates. (Data Source: RVDSS Canada)
Dr. Allison McGeer, an infectious disease specialist at Mount Sinai Hospital in Toronto, described this flu season as unusual, noting ‘a lot of both H3N2 and H1N1 activity happening at the same time,’ as reported by The Canadian Press. Dr. Jesse Papenburg, assistant professor of paediatrics at McGill University, also quoted in The Canadian Press article, added that this co-circulation is intensifying the season’s severity, noting, ‘It’s kind of like there are two outbreaks or two epidemics … occurring at the same time of two different strains of influenza A.’ These observations highlight the concurrent circulation of multiple influenza A strains, aligning with complex epidemiological patterns detected by the AI4Casting Hub forecasting models. This season’s deviation from typical patterns underscores the need for adaptive forecasting, real-time data integration, and collaborative efforts to enhance preparedness strategies.
Forecasting Influenza Trends: AI4Casting Hub Projections
The AI4Casting Hub’s four-week-ahead projections, developed by participating research teams, demonstrate a correlation with observed laboratory detection trends. The accompanying graph (Fig. 2) illustrates varied projections for weekly influenza laboratory detection percentages, with models indicating both moderate and steeper increases in influenza activity through March 2025. The ensemble model projects a continued rise in cases, potentially reaching 29.5% national positivity by the week ending March 15. You can find more of these static graphs for Influenza, RSV and Covid-19 for different Canadian regions right here.
As reported by Global News, Dr. Christopher Labos, a Montreal-based cardiologist and epidemiologist, observed that this flu season is ‘reverting to pre-COVID-19 patterns,’ with cases peaking in late January and early February, an observation that aligns with trends in the AI4Casting Hub’s forecasts. He attributes this to the disruption of normal viral circulation patterns during the COVID-19 pandemic, which caused atypical flu season peaks in recent years.
While Labos predicts a plateau as warmer weather arrives, AI4Casting Hub projections indicate influenza activity may continue rising, potentially reaching 29.5% positivity by mid-March before stabilizing. These insights highlight the need for real-time surveillance and adaptive forecasting to support public health response.
Acknowledging the uncertainties in long-term forecasting, the AI4Casting Hub will continue refining its models using updated surveillance data. Public health officials, researchers, and healthcare providers can access real-time influenza trends and insights via the AI4Casting Hub’s RVDSS Dashboard.
For more details and real-time updates on influenza trends, visit the AI4Casting Hub’s RVDSS Dashboard: https://4castinghub.uoguelph.ca/respiratory-virus-detections/