Zani, Matteo

ABSTRACT Anti‐Spike monoclonal antibodies (mAbs) progressively lost efficacy during the COVID‐19 pandemic due to the emergence and predominance of resistant SARS‐CoV‐2 variants. By contrast, high‐titre COVID‐19 convalescent plasma (CCP) collected from vaccinated donors recently recovered from infection provides a polyclonal source of antibodies that remains effective in clearing SARS‐CoV‐2 in immunosuppressed patients, unable to mount an adequate immune response against the virus. We conducted a systematic review and individual participant data meta‐analysis to examine the effect of CCP in immunocompromised patients persistently positive for SARS‐CoV‐2 viraemia following mAb therapy, and to evaluate possible biological factors associated with a favourable outcome. Electronic databases were searched for studies published from January 2020 to January 2026. All studies including eligible cases were considered in the systematic review. Unpublished cases were also collected from investigators of the selected studies. The protocol was registered at PROSPERO (CRD420251142891). Forty‐seven cases (30 cases from 12 published studies and 17 unpublished cases) were included. In 33 out of 47 patients (70.2%) with a mAb‐resistant infection, SARS‐CoV‐2 clearance occurred following CCP transfusion, with a mean of 2.7 CCP units administered. In logistic regression, total CCP volume transfused was positively associated with SARS‐CoV‐2 clearance. In conclusion, CCP transfusion was associated with SARS‐CoV‐2 clearance in persistently positive immunocompromised patients following failure of anti‐Spike mAb therapy.

ImportancePatients 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.ObjectiveTo 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 SourcesOn August 12, 2022, a systematic search was performed for clinical studies of COVID-19 convalescent plasma use in patients who are immunocompromised.Study SelectionRandomized 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 SynthesisThe 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 MeauresThe 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.ResultsThis 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 RelevanceThese findings suggest that transfusion of COVID-19 convalescent plasma is associated with mortality benefit for patients who are immunocompromised and have COVID-19.