A trend of dropping anti‐SARS‐CoV‐2 plaque reduction neutralization test titers over time in Canadian convalescent plasma donors

Background Convalescent plasma products are a potential passive immunotherapy for Coronavirus disease 2019 (COVID‐19) disease. Various approaches have been utilized to determine the concentration of Severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2)‐neutralizing antibodies in plasma products. The Canadian Blood Services used Plaque Reduction Neutralization Test 50 (PRNT50)‐generated values to qualify convalescent plasma donations supporting clinical trials in Canada. This manuscript describes changes in PRNT50 titers of repeat male plasma donations collected approximately 1–4 months after onset of COVID‐19 signs and symptoms in donors. Study Design and Methods Men were eligible to donate if they: met standard criteria, were