This is a summary, written by members of the CITF Secretariat, of Canadian Blood Services’ September 2022 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.

Consistent with the continued prevalence of the Omicron variants (predominantly BA.4, BA.5 and BA.5 subvariants), infection-acquired seropositivity continues to increase among blood donors, up to 65.41% by the end of September, from 60% in the last week of August. These data come from Canadian Blood Services.

Key findings:

  • Infection-acquired seroprevalence in September was 63.2%, higher than in August (58.5%). There was a modest week-to-week change over the course of September from 61.1% to 63.4% to 62.9% to 65.4% in the last week.
  • Spike antibodies (suggesting vaccine-induced) were present in 100% of blood donors, consistent with the roll-out of third and fourth doses of vaccine. Peak immunity occurred earlier in older age groups due to policies to vaccinate this cohort earlier.
  • Consistent with previous surveys, donors aged 17-24 had the highest infection-acquired seroprevalence rate (78.3%) compared to other age groups (72.4% for 25-39-year-olds, 64.8% for 40-59-year-olds and 46.7% for those aged 60+). The infection-acquired seroprevalence rate increased in all age groups compared to August.
  • The infection-acquired seroprevalence rate increased in all provinces except Newfoundland and Prince Edward Island.
  • Racialized groups continued to have a higher infection-acquired seroprevalence rate compared to white donors (70.1% vs. 61.8%).
  • The gap in infection-acquired seroprevalence between the most materially deprived and the least materially deprived closed somewhat. Among the most materially deprived, the seroprevalence rate due to infection increased from 61.8% in August to 65% in September, while it increased from 57% in August to 63% in September among the least materially deprived.


The latest report builds on the  September 1st-14th, 2022 report and includes samples from 31,606 donors between the ages of 17 and about 60 who donated blood between September 1st and 30th, in all of 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.

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.