International Survey of Trials of Convalescent Plasma to Treat COVID-19 Infection

The collection and clinical use of COVID-19 convalescent plasma (CCP) as a therapy for COVID-19 infection is under development and early use in many centers worldwide. We conducted an international survey of centers undertaking studies of CCP to provide understanding of the common themes and differences between them. Sixty-four studies in 22 countries were identified from clinical trial registries and personal contacts of the authors. Twenty of the 64 centers (31%) from 12 of 22 countries (55%) responded to the survey. Of the 20 studies, 11 were randomized controlled trials (RCTs), and 9 were case series. Only 4 of the RCTs plan to recruit 400 patients or more, and only 3 RCTs were blinded. The majority of studies will study the effect of CCP on sick patients requiring hospitalization and those requiring critical care, and none is examining the role of CCP in non-infected at-risk individuals. A wide variety of primary and secondary outcomes are being used. The donor eligibility criteria among the studies are very similar, and the use of plasmapheresis for the collection of CCP is almost universal. The planned dose of CCP ranges from as little as 200 mL to well over 1 L, but is 400 to 800 mL or 4 mL/kg or greater in all the RCTs. There is considerable variability in donor antibody testing with no consistency regarding the cut-off for antibody titer for acceptance as CCP or the use of pathogen-inactivation. Our survey provides an understanding of the similarities and differences among the studies of CCP, and that by virtue of their design some studies may be more informative than others.