This is a summary written by members of the CITF Secretariat of Canadian Blood Services’ mid-January 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.
Despite all donors having vaccine-related antibodies, seroprevalence data from Canadian Blood Services suggested that 76.2% of donors had infection-acquired antibodies by mid-January 2023. This estimate was higher than the 73.5% estimate recorded at the end of December 2022. Close to 90% of young (aged 17 to 24) Canadians recorded seropositivity due to infection by mid-January. Donors declaring themselves racialized continued to have higher seroprevalence due to infection than self-declared white donors.
- There was an increase over the 15-day reporting period, from 73.5% in December to 76.2% in the first week of January. The rate remained the same in the second week of January.
- Donors aged 17-24 years had the highest seroprevalence rate compared to other age groups (89% (in the week of January 8-15, and 85.7% from January 1-7).
- Self-declared racialized groups continued to have higher seroprevalence compared with donors considering themselves white: 82% vs 75% in the week of January 8-15, up from 81% vs 75% between January 1-7.
- The difference in infection-acquired seroprevalence observed between the most and least materially deprived populations was around 5%: seroprevalence was 79% among the most deprived and 75% among the least by mid-January.
- Anti-spike antibodies were present in all blood donors. This may be related to a combination of vaccination and breakthrough natural infections. Anti-spike concentrations, indicative of vaccination, has increased since the summer of 2022, however in January, they started to decline, particularly in older age groups, which maybe due to waning.
The latest report builds on the end of December 2022 report and includes samples from 16,297 unique donors over the age of 17 who donated blood between January 1st and January 15th, 2023, across Canada, excluding Quebec and the Territories.
It should be noted that 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.