This is a summary written by members of the CITF Secretariat of Canadian Blood Services’ July 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 suggests that seroprevalence due to infection was stable at 80% among Canadian blood donors by the end of July. The report found that 79.9% had anti-nucleocapsid antibodies by July 31st, 2023, comparable to 80.0% by June 30th, 2023. The percentage of younger donors (ages 17-24) who had infection-acquired seroprevalence was 90.0% by July 31st, 2023, which is similar to the 90.2% observed by the end of June. Self-declared Indigenous and racialized donors continued to have higher seroprevalence due to infection than did self-declared white donors.

Key findings:

  • Infection-acquired seroprevalence by July 31st, 2023 was 79.9%, similar to the 80% mark by June 30th, 2023.
  • Donors aged 17-24 years old continued to have the highest seroprevalence due to infection of all age groups at 90.0%, just slightly lower than 90.2% in June.
  • As in previous Canadian Blood Services surveys, self-declared racialized donors continued to have higher infection-acquired seroprevalence (84.7%) than self-declared white donors (78.4%).
  • The most materially deprived donors (based on postal code) continued to have higher infection-acquired seroprevalence than the least materially deprived individuals (80.8% vs. 79.8%) but this gap was less when compared to June (82.0% vs. 78.7%).
  • All blood donors had antibodies against the spike protein, indicating that they had active immune responses due to either vaccination or infection. Interestingly, those who tested positive for antibodies against the nucleocapsid protein tended to have higher concentrations of spike antibodies compared to those who only had spike antibodies. This is thought to be related to hybrid immunity (a combination of vaccination-induced and infection-acquired immunity).


The latest report builds on the June 2023 report and includes samples from 31,978 unique donors over the age of 17 who donated blood between July 1st and July 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.