This is a summary written by members of the CITF Secretariat of Canadian Blood Services’ August 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 79.03% among Canadian blood donors in August 2023. This was similar to the 79.94% seroprevalence observed in July 2023 (the difference could be due to sampling variation and was not statistically significant). The percentage of younger donors (ages 17-24) who had infection-acquired seroprevalence was 87.87% by August 31st, 2023, rather similar to the 90.00% observed at the end of July, 2023. Self-declared Indigenous and racialized donors continued to have higher seroprevalence due to infection than self-declared white donors.

Key findings:

  • Infection-acquired seroprevalence by August 31, 2023 was 79.03%, compared to 79.94% observed by July 31, 2023.
  • Donors aged 17 to 24 years old continued to have the highest seroprevalence due to infection of all age groups at 87.87%.
  • As in previous Canadian Blood Services surveys, self-declared racialized donors continued to have higher infection-acquired seroprevalence (84.52%) than self-declared white donors (77.28%). Infection-acquired seroprevalence observed in self-declared racialized populations remained stable compared to the 84.72% observed in July.
  • The most materially deprived donors (based on postal code of residence) continued to have higher infection-acquired seroprevalence than the least materially deprived individuals (80.84% vs. 78.01%).
  • 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.

Conclusion

The latest report builds on the July 2023 report and includes samples from 31,776 unique donors over the age of 17 who donated blood between August 1st and August 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.