Seroprevalence due to infection in blood donors also stabilized in March

The latest CITF-funded seroprevalence report from Canadian Blood Services showed that infection-acquired seroprevalence among Canadian adult blood donors was stable between February and March (78.7% in March, compared to 77.6% in February). Young donors (aged 17-24) continued to have the highest infection-acquired seroprevalence.

Key findings:

• Seroprevalence due to infection stabilized in March at 78.7%, only slightly higher than in February (77.6%). Over March, there was slight week-to-week variation from 78% to 78.4% to 79.4% to 78.7%.
• Consistent with previous Canadian Blood Services surveys, donors aged 17-24 had the highest seroprevalence at 89.2%. Seroprevalence was 79.1% in donors aged 40-59 and 67.4% in donors aged 60 or above.
• Self-declared Black, Indigenous, and racialized people continued to have a higher seroprevalence (84.3%) than did self-declared white donors (77.2%).
• The most materially deprived donors (based on postal code) continued to have higher seroprevalence due to infection, compared to the least materially deprived individuals (80.1% vs 77.5%).
• Anti-spike antibodies were present in all blood donors. This reflects Canada’s high vaccination coverage, combined with infection-acquired immunity.

Conclusion

The latest report builds on the mid-March 2023 report and includes samples from 30,793 unique donors over the age of 17 who donated blood between March 1^st and March 31^st, 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.