Blood donor return behavior in South Africa and the United States before and during the COVID-19 pandemic.

Abstract

Studies preceding the COVID-19 pandemic found that slower time-to-return was associated with first-time, deferred, and mobile drive blood donors. How donor return dynamics changed during the COVID-19 pandemic is not well understood. We analyzed visits by whole blood donors from 2017 to 2022 in South Africa (SA) and the United States (US) stratified by mobile and fixed environment, first-time and repeat donor status, and pre-COVID19 (before March 2020) and intra-COVID19. We used Kaplan-Meier curves to characterize time-to-return, cumulative incidence functions to analyze switching between donation environments, and Cox proportional hazards models to analyze factors influencing time-to-return. Overall time-to-return was shorter in SA. Pre-COVID19, the proportion of donors returning within a year of becoming eligible was lower for deferred donors in both countries regardless of donation environment and deferral type. Intra-COVID19, the gap between deferred and non-deferred donors widened in the US but narrowed in SA, where efforts to schedule return visits from deferred donors were intensified, particularly for non-hemoglobin-related deferrals. Intra-COVID19, the proportion of donors returning within a year in SA was higher for deferred first-time donors (>81%) than for successful first-time donors (80% at fixed sites; 69% at mobile drives). The pandemic complicated efforts to recruit new donors and schedule returning visits after completed donations. Concerted efforts to improve time-to-return for deferred donors helped mitigate donation loss in SA during the public health emergency.