Efficacy and Safety of Convalescent Plasma for COVID-19: A Systematic Review and Meta-analysis

Convalescent plasma is currently being used in the treatment of COVID-19. Recommendations regarding use convalescent plasma in COVID-19 requires systematic summaries of available evidence. We searched the databases Medline, Embase, Cochrane CENTRAL, Epistomonikos, Medrxiv and Biorxiv. Title/abstract screening, full text screening and data abstraction were carried out in duplicate by two reviewers. Pooled effect sizes and 95% confidence intervals were calculated using random effects meta-analysis. GRADE tool was used to rate the certainty of evidence. Twenty two studies were found eligible for inclusion: nine randomized controlled trials and thirteen cohort studies. Low certainty evidence from eight RCTs showed inconclusive effects of convalescent plasma on mortality at 28 days (OR 0.85, 95% CI 0.61 to 1.18). Low certainty evidence from thirteen cohort studies showed a reduction in mortality at 28 days (OR 0.66, 95% CI 0.53 to 0.82). The pooled OR for clinical improvement was 1.07 (95% CI 0.86 to 1.34) representing low certainty evidence. Evidence from three RCTs showed inconclusive effect of CP on the need for mechanical ventilation (OR 1.20, 95% CI 0.72 to 1.98). Four cohort studies reporting unadjusted estimates suggested a reduction in the need for mechanical ventilation with convalescent plasma (OR 0.80 95% CI 0.71 to 0.91, low certainty). Pooled estimates from 2 RCTs showed inconclusive effects of convalescent plasma on the proportion of patients with nondetectable levels of virus in nasopharyngeal specimens on day 3 (OR 3.62, 95% CI 0.43, 30.49, very low-quality evidence). The present review reports uncertain estimates on the efficacy of convalescent plasma in the treatment of COVID-19. There is low certainty evidence of a possible reduction in mortality and mechanical ventilation, a faster viral clearance and the absence of any serious adverse events. However, its efficacy for these outcomes requires evidence from good quality and adequately powered randomized controlled trials. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12288-021-01417-w.