The Effect of the COVID-19 Pandemic on Unrelated Allogeneic Hematopoietic Donor Collections and Safety

Background and Objectives: The COVID-19 pandemic profoundly influenced unrelated donor (UD) allogeneic peripheral blood stem cell (PBSC) collections. Changes included efforts to minimize COVID-19 exposure to donors and cryopreservation of products. The extent to which the efficacy and safety of PBSC donations were affected by the pandemic is unknown. Methods: Prospective cohort analysis of PBSC collections comparing pre-pandemic (01 April 2019–14 March 2020) and pandemic (15 March 2020–31 March 2022) eras. Results: Of a total of 291 PBSC collections, cryopreservation was undertaken in 71.4% of pandemic donations compared to 1.1% pre-pandemic. The mean requested CD34(+) cell dose/kg increased from 4.9 ± 0.2 × 10(6) pre-pandemic to 5.4 ± 0.1 × 10(6) during the pandemic. Despite this increased demand, the proportion of collections that met or exceeded the requested cell dose did not change, and the mean CD34(+) cell doses collected (8.9 ± 0.5 × 10(6) pre-pandemic vs. 9.7 ± 0.4 × 10(6) during the pandemic) remained above requested targets. Central-line placements were more frequent, and severe adverse events in donors increased during the pandemic. Conclusion: Cryopreservation of UD PBSC products increased during the pandemic. In association with this, requested cell doses for PBSC collections increased. Collection targets were met or exceeded at the same frequency, signaling high donor and collection center commitment. This was at the expense of increased donor or product-related severe adverse events. We highlight the need for heightened vigilance about donor safety as demands on donors have increased since the pandemic.