COVID-19 Convalescent Plasma for the Treatment of Immunocompromised Patients: A Systematic Review and Meta-analysis

IMPORTANCE: Patients who are immunocompromised have increased risk for morbidity and mortality associated with coronavirus disease 2019 (COVID-19) because they less frequently mount antibody responses to vaccines. Although neutralizing anti-spike monoclonal-antibody treatment has been widely used to treat COVID-19, evolutions of SARS-CoV-2 have been associated with monoclonal antibody-resistant SARS-CoV-2 variants and greater virulence and transmissibility of SARS-CoV-2. Thus, the therapeutic use of COVID-19 convalescent plasma has increased on the presumption that such plasma contains potentially therapeutic antibodies to SARS-CoV-2 that can be passively transferred to the plasma recipient. OBJECTIVE: To assess the growing number of reports of clinical experiences of patients with COVID-19 who are immunocompromised and treated with specific neutralizing antibodies via COVID-19 convalescent plasma transfusion. DATA SOURCES: On August 12, 2022, a systematic search was performed for clinical studies of COVID-19 convalescent plasma use in patients who are immunocompromised. STUDY SELECTION: Randomized clinical trials, matched cohort studies, and case report or series on COVID-19 convalescent plasma use in patients who are immunocompromised were included. The electronic search yielded 462 unique records, of which 199 were considered for full-text screening. DATA EXTRACTION AND SYNTHESIS: The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were extracted by 3 independent reviewers in duplicate and pooled. MAIN OUTCOMES AND MEAURES: The prespecified end point was all-cause mortality after COVID-19 convalescent plasma transfusion; exploratory subgroup analyses were performed based on putative factors associated with the potential mortality benefit of convalescent plasma. RESULTS: This systematic review and meta-analysis included 3 randomized clinical trials enrolling 1487 participants and 5 controlled studies. Additionally, 125 case series or reports enrolling 265 participants and 13 uncontrolled large case series enrolling 358 participants were included. Separate meta-analyses, using models both stratified and pooled by study type (ie, randomized clinical trials and matched cohort studies), demonstrated that transfusion of COVID-19 convalescent plasma was associated with a decrease in mortality compared with the control cohort for the amalgam of both randomized clinical trials and matched cohort studies (risk ratio [RR], 0.63 [95% CI, 0.50-0.79]). CONCLUSIONS AND RELEVANCE: These findings suggest that transfusion of COVID-19 convalescent plasma is associated with mortality benefit for patients who are immunocompromised and have COVID-19.