Treatment with convalescent plasma for COVID-19 with respect to experience from prior coronavirus epidemics

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a major concern all over the world. There is currently no proven vaccine and specific treatment to be effective for SARS-CoV-2 infection. Convalescent plasma obtained from patients who have recently recovered from infection has been used as a therapeutic intervention in previous coronavirus-related pandemics including SARS-CoV, MERS-CoV, and now COVID-19. The presence of neutralizing antibodies which specifically recognize SARS-CoV-2 are thought to mediate antiviral effects before patient develop their own humoral immune responses leading to cytokine storm and disease severity. In this review, we have summarized existing literature on convalescent plasma for the treatment of MERS-CoV, SARS-CoV, and COVID-19. Data from studies using convalescent plasma in COVID-19 suggest clinical improvements such as reduced viral load, oxygen requirement, and radiographic resolution. Although randomized clinical trials describing the benefit of convalescent plasma in COVID-19 are limited but these studies point to better outcomes of convalescent plasma treatment when administered earlier in the course of the disease. However, more precise randomized trials are needed to investigate different indications such as time of plasma administration and/or combination with other antiviral treatments.