Convalescent plasma or hyperimmune immunoglobulin for people with COVID‐19: a living systematic review

Background Convalescent plasma and hyperimmune immunoglobulin may reduce mortality in patients with viral respiratory diseases, and are currently being investigated in trials as potential therapy for coronavirus disease 2019 (COVID‐19). A thorough understanding of the current body of evidence regarding the benefits and risks is required. Objectives To continually assess, as more evidence becomes available, whether convalescent plasma or hyperimmune immunoglobulin transfusion is effective and safe in treatment of people with COVID‐19. Search methods We searched the World Health Organization (WHO) COVID‐19 Global Research Database, MEDLINE, Embase, Cochrane COVID‐19 Study Register, Centers for Disease Control and Prevention COVID‐19 Research Article Database and trial registries to identify completed and ongoing studies on 4 June 2020. Selection criteria We followed standard Cochrane methodology. We included studies evaluating convalescent plasma or hyperimmune immunoglobulin for people with COVID‐19, irrespective of study design, disease severity, age, gender or ethnicity. We excluded studies including populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)) and studies evaluating standard immunoglobulin. Data collection and analysis We followed standard Cochrane methodology. To assess bias in included studies, we used the Cochrane 'Risk of bias' tool for randomised controlled trials (RCTs), the Risk of Bias in Non‐randomised Studies ‐ of Interventions (ROBINS‐I) tool for controlled non‐randomised studies of interventions (NRSIs), and the assessment criteria for observational studies, provided by Cochrane Childhood Cancer for non‐controlled NRSIs. Main results This is the first living update of our review. We included 20 studies (1 RCT, 3 controlled NRSIs, 16 non‐controlled NRSIs) with 5443 participants, of whom 5211 received convalescent plasma, and identified a further 98 ongoing studies evaluating convalescent plasma or hyperimmune immunoglobulin, of which 50 are randomised. We did not identify any completed studies evaluating hyperimmune immunoglobulin. Overall risk of bias of included studies was high, due to study design, type of participants, and other previous or concurrent treatments. Effectiveness of convalescent plasma for people with COVID‐19 We included results from four controlled studies (1 RCT (stopped early) with 103 participants, of whom 52 received convalescent pl