This is a summary written by members of the CITF Secretariat of Canadian Blood Services’ October 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 is now stable among Canadian blood donors at approximately 80%. The report, which profiles the results of samples from adult blood donors, found that 81.6% had anti-nucleocapsid antibodies (due to infection) in October 2023, up very slightly from 80.1% in September 2023, but this difference is not statistically significant. The percentage of young donors ages 17-24 who had infection-acquired antibodies was 91.8% by October 31st, 2023, slightly higher than the 90.25% observed in September 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 October 31, 2023 was 81.62%, similar to the 80.12% observed by September 30, 2023. The week-to-week variation over October was 81.95% to 81.31% to 82.09% to 81.24%.
  • Donors aged 17-24 years continued to have the highest seroprevalence due to infection of all age groups at 91.8% by October 31st, 2023, increasing slightly from the 90.25% observed in September 2023.
  • As in previous Canadian Blood Services studies, self-declared racialized donors continued to have higher infection-acquired seroprevalence (86.78%) than self-declared white donors (80.15%). Infection-acquired seroprevalence observed in self-declared racialized populations was similar to that observed in September 2023 (86.1% vs. 78.42%).
  • Infection-acquired seroprevalence among the most and least materially deprived donors (based on postal code) was similar in October 2023 (82.03% vs. 82.27%).
  • All blood donors had antibodies against the spike protein, indicating that all donors have active immune responses due to either vaccination or infection. Interestingly, those who tested positive for antibodies against the nucleocapsid protein continued to have higher concentrations of spike antibodies compared to those who only had spike antibodies.

Conclusion

The latest report builds on the September 2023 report and includes samples from 31, 977 unique donors over the age of 17 who donated blood between October 1st and October 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.