Monitoring respiratory illness trends is important for robust public health planning and reducing societal and healthcare burdens. While influenza and respiratory syncytial virus typically follow a seasonal pattern, peaking in activity from November to April, SARS-CoV-2 is less predictable. Recent wastewater data reveal that viral SARS-CoV-2 concentrations sometimes rise outside of flu season. Additionally, SARS-CoV-2's high transmissibility and rapid evolution, which affects immunity, keep the risk of infection present year-round.
Statistics Canada, in partnership with the National Microbiology Laboratory from the Public Health Agency of Canada, have been collaborating on the Canadian Wastewater Survey (CWS) to monitor the levels of SARS-CoV-2, the virus that causes COVID-19, in the wastewater of five Canadian cities. As the virus continues to circulate, the CWS provides valuable insights on its activity in the population.
This release looks back at observed trends from January 2023 to February 2025.
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