Convalescent plasma has been shown to be safe and effective for treatment of several diseases. Preliminary data indicate that it is safe for treatment of COVID-19. We found that viremia upon admission identifies patients at 7 fold increased risk of admission to intensive care and 8 fold increased risk of death. CP treatment appeared to result in rapid viral clearance in a small case series. CP appeared to be well tolerated in a phase I study in which patients only received one dose of CP and a phase II study in which CP was given until viremia disappeared (unpublished data).
Randomised controlled studies assessing the efficacy of CP are lacking and thus the efficacy of CP is unknown. Preliminary data indicate that treatment should be given early, prior to development of severe illness. Detection of viremia upon admission identifies a group at high risk of severe disease and death that has the most to benefit from CP. Phase II study data indicates that treatment should be given until SARS-CoV-2 is no longer detected in serum and the donor antibody neutralization titres should be ≥1/640. A randomised controlled trial in which viremic patients are treated with CP with the equivalent of an antibody titre ≥1/640 is thus required to determine if CP can be an effective COVID-19 treatment.
