This is a summary, written by members of the CITF Secretariat, of

O’Brien S, Caffrey N, Yi Q-L, Bolotin S, Janjua NZ, Binka M, Quach Thanh C, Stein D, Lang A, Colquhoun A, Pambrun C, Reedman C, Drews SJ. Cross-Canada variability in blood donor SARS-CoV-2 seroprevalence by social determinants of health, Microbiology Spectrum, 10 January 2023, DOI:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

In a paper published in Microbiology Spectrum, CITF-funded researchers, including at Canadian Blood Services, showed that infection-acquired immunity to SARS-CoV-2 varied, in 2021, by age, region, racial group, the neighbourhoods in which people lived and whether they were materially or socially deprived (had fewer contacts). Interestingly, these factors were not consistent throughout all provinces and regions.

Key findings (all relating to infection-acquired seropositivity):

  • Being male was a predictor of seropositivity in all regions except the Atlantic provinces.
  • Younger age was highly predictive of seropositivity and decreased with each progressively older age group.
  • Self-identified racialized populations were associated with higher seroprevalence in British Columbia, Ontario, and the Atlantic regions, but not in Alberta and the Prairies.
  • Living in a materially deprived neighbourhood predicted higher seroprevalence in all regions except the Atlantic provinces.
  • Greater social deprivation (single individuals and one parent families) was associated with lower seroprevalence in British Columbia and Ontario but not in Alberta and the Prairie provinces.

These findings highlight that there is a need to address racial and socioeconomic disparities in COVID-19 infections.

Canadian Blood Services collects blood donations from generally healthy individuals, 17 years of age and older, in all provinces except Quebec and the Northern Territories. Samples collected between January and December 2021 were randomly selected for serologic testing every month.