This is a summary written by members of the CITF Secretariat of Canadian Blood Services’ May 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 seroprevalence report from Canadian Blood Services shows that approximately 79.6% of adult blood donors had infection-acquired seroprevalence in May, which is similar to April (79.4%). Younger donors (ages 17-24), self-declared racialized and Indigenous people continued to have high seroprevalence due to infection.

Key findings:

  • Infection-acquired seroprevalence in May was 79.6%, similar to April (79.4%).
  • Donors aged 17-24 years old had the highest seroprevalence rate at 89.9% compared to other age groups.
  • As in previous Canadian Blood Services surveys, self-declared racialized and Indigenous people had higher seroprevalence (84.7%) than self-declared white donors (78.1%).
  • The most materially deprived donors (based on postal code of residence) continued to have higher infection-acquired seroprevalence, compared to the least materially deprived individuals (81.2% vs 78.6%), similar to April.
  • All blood donors had anti-spike antibodies, which reflects Canada’s high vaccination coverage, combined with infection-acquired immunity. However, spike antibody concentrations tended to be higher among those who were also positive for nucleocapsid antibodies, compared to those positive for spike antibodies only.


The latest report builds on the April 2023 report and includes samples from 31,711 unique donors over the age of 17 who donated blood between May 1st and May 31st, 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.