Convalescent plasma therapy has been used successfully in the past to treat respiratory infections. In SARS-CoV-2, there was initially strong evidence in favor of convalescent plasma therapy from a large observational study but the evidence from recent randomized controlled trials has been mixed. However, two of those studies provided convalescent plasma therapy on average 8 days after diagnosis despite earlier data proving that the therapy is most effective when given within 3 days of diagnosis. Another more recent randomized controlled trial found evidence in support of convalescent plasma therapy and we believe that it is no coincidence that they administered convalescent plasma therapy within 3 days of symptom onset. We call for more robustly planned randomized controlled studies to further reliably determine the efficacy of convalescent plasma therapy against SARS-CoV-2. Progress has been made with developing a vaccine but there is likely to be a substantial lag in widespread administration of the vaccine, especially in poorer countries. We therefore propose that patients with SARS-CoV-2 infection should be considered for early ambulatory administration of high-dose convalescent plasma in order to reduce the burden of severe SARS-CoV-2 disease.
The Evidence for High-Titer Convalescent Plasma in SARS-CoV-2