Association of SARS ‐ CoV ‐2 infection with interdonation interval: A matched cohort study of plasma donors in Québec, Canada

Abstract Background and Objectives Blood services witnessed significant declines of donor returns during the COVID‐19 pandemic. Should another public health crisis occur, this experience may provide important insights for the development of strategies to maximize donor return. Here, we explored how contracting a SARS‐CoV‐2 infection impacted interdonation interval. Materials and Methods This was a retrospective cohort study of plasma donors who were not SARS‐CoV‐2‐vaccinated at the time of inclusion. The study took place in Québec, Canada. Donors were included if they had donated plasma twice: once between March 1 2020 and 30 June 2020 and once more within the next 24 months. Donors with (‘infected’) and without (‘non‐infected’) a self‐reported SARS‐CoV‐2 infection were matched 1:1 based on sex, age and number of previous donations. Cox proportional hazard ratios (HRs) and 95% confidence intervals (CIs) were reported. Results The matched cohorts each comprised 108 donors, including 50.0% of female donors (mean age ± standard deviation years: infected = 40.5 ± 16.2; non‐infected = 41.0 ± 16.4). Interdonation interval was significantly longer among infected donors than among non‐infected donors, whether it be in the full cohort (HR 95% CI = 0.566 0.428–0.749) or among female donors (HR 95% CI = 0.429 0.278–0.660)—but not among male donors (HR 95% CI = 0.813 0.527–1.254). Conclusion In this study, a self‐reported SARS‐CoV‐2 infection was associated with a significantly longer interdonation interval.