A randomized clinical trial of 86 hospitalized COVID-19 patients comparing standard care to treatment with 300ml convalescent plasma containing high titers of neutralizing SARS-CoV-2 antibodies showed no overall clinical benefit. A comprehensive translational approach investigated virological and immunological responses to determine which patients might benefit. Convalescent plasma was safe but did not improve survival, disease course, viral clearance, antibody development, or inflammatory cytokine levels. Most patients already had potent neutralizing antibodies at admission, comparable to plasma donors, leading to early trial termination. Future studies should focus on early disease stages or before autologous humoral response.

Arvind Gharbaran, Carlijn C. E. Jordans, Corine GeurtsvanKessel, Jan G. den Hollander, Faiz Karim, Femke P. N. Mollema, Janneke E. Stalenhoef – Schukken, Anthonuis Dofferhoff, Inge Ludwig, Adrianus Koster, Robert-Jan Hassing, Jeannet C. Bos, Geert R. van Pottelberge, Imro N. Vlasveld, Heidi S. M. Ammerlaan, Elena M. van Leeuwen – Segrecanul, Jelle Miedema, Menno van der Eerden, Thijs J. Schrama, Grigorios Papageorgiou, Peter te Boekhorst, Francis H. Swaneveld, Yvonne M. Mueller, Marco W. J. Schreurs, Jeroen J. A. van Kampen, Barry Rockx, Nisreen M. A. Okba, Peter D. Katsikis, Marion P. G. Koopmans, Bart L. Haagmans, Casper Rokx, Bart J. A. Rijnders