Donor mobilization during U.S. mass casualty and disaster events: Differential effects on whole blood and apheresis platelet supply.

backgroundMass casualty and disaster events (MCEs) and national blood donation appeals generate surges in blood donation, but how these responses differ by product type, donor demographics, and retention remains incompletely understood, particularly for apheresis platelets. STUDY DESIGN AND

methodsWe analyzed donation data from five major U.S. MCEs and five national blood donation appeals between 2000 and 2024, characterizing whole blood (WB) and platelet donations by donor age, first-time versus repeat status, and return within 1 year.

resultsWB donation demonstrated rapid, high-amplitude surges during MCEs that resolved within 1-2 weeks, driven in part by younger and first-time donors. In contrast, appeals produced smaller increases sustained through the duration of the appeal. Platelet donation followed a distinct pattern, with a smaller, yet slightly longer surge response during MCEs and more robust increases during national blood donation appeals, while both relied almost exclusively on older, repeat donors. Donor retention differed primarily by donor history. Repeat donors were substantially more likely to return than first-time donors across age groups and event types, with older repeat donors showing the highest retention. DISCUSSION: These findings highlight structural differences between WB and platelet donor systems with direct implications for disaster preparedness and long-term blood supply resilience in the United States.