Early experience with convalescent plasma as immunotherapy for COVID-19 in China: Knowns and unknowns

In the absence of a vaccine or specific drug treatment options for coronavirus disease (COVID-19), attention has been shifted in China to the possible therapeutic use of convalescent plasma. COVID-19 convalescent plasma (CCP) is currently under investigation. We summarized clinical studies and other research data available as of 5 May 2020 on CCP therapy according to the Clinical Treatment Guideline of COVID-19 Convalescent Plasma in China, as well as clinical experience at the First Affiliated Hospital of Zhejiang University, as part of a comprehensive anti-epidemic strategy.

As of 5 May 2020, when the epidemic was well-controlled in China, healthcare databases and sources of English literature relating to convalescent plasma were searched and reviewed. Sources of clinical and methodological heterogeneity were identified.

As of 5 May 2020, up to 2000 samples of CCP had been collected across China and administered to 700 COVID-19 patients. From donors, 200-400 ml of plasma was collected at each donation, with antibody titres > 1:160. We identified three clinical studies for COVID-19 in China. Analyses showed a statistically significant improvement in clinical outcomes compared with untreated cases (P < 0.001). No adverse effects were reported.

From initial studies, convalescent plasma therapy appears effective and safe for COVID-19. However, there is clearly a need for well-designed RCTs (randomized controlled trials) or other formal studies to further evaluate the efficacy and any potential adverse effects of CCP.