This is a summary written by members of the CITF Secretariat of Canadian Blood Services’ September 2023 report of data gathered from blood donations. The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

The latest CITF-funded report from Canadian Blood Services suggested that seroprevalence due to infection was 80.1% among Canadian blood donors at the end of September 2023. This increased slightly from the 79.0% seroprevalence observed in August 2023. The percentage of younger donors (ages 17-24) who had infection-acquired seroprevalence was 90.3% by September 30th, 2023, higher than the 87.9% observed by August 31st, 2023. Self-declared Black, Indigenous, and racialized donors continued to have higher seroprevalence due to infection than self-declared white donors.

Key findings:

  • Infection-acquired seroprevalence by September 30th, 2023 was 80.1%, compared to 79.0% observed by August 31st, 2023.
  • Donors aged 17- to 24-years-old continued to have the highest seroprevalence due to infection of all age groups at 90.3%.
  • As in previous Canadian Blood Services surveys, self-declared racialized donors continued to have higher infection-acquired seroprevalence (86.1%), a slight increase from August (84.5%), than self-declared white donors (78.4%).
  • The most materially deprived donors (based on postal code of residence) continued to have higher infection-acquired seroprevalence than the least materially deprived individuals (81.5% vs. 79.5%).
  • All blood donors had antibodies against the spike protein, indicating that they had active immune responses due to either vaccination or infection or both. Those who tested positive for antibodies against the nucleocapsid protein continued to have higher concentrations of spike antibodies compared to those who did not have anti-nucleocapsid antibodies.


The latest report builds on the August 2023 report and includes samples from 31,764 unique donors over the age of 17 who donated blood between September 1st and September 30th, 2023, across Canada, excluding Quebec and the Territories.

Individuals who choose to donate blood are generally in good health and are more likely to live in populous urban areas. Percentages were adjusted for test characteristics and population distribution.

Explore our interactive webpage, updated every month, featuring the latest aggregated data gathered by the Canadian Blood Services and Héma-Québec on SARS-CoV-2 seroprevalence in Canada.