High-Titer COVID-19 Convalescent Plasma Reduces Risk for All-Cause Hospitalization

Results of a meta-analysis published in Clinical Infectious Disease suggest that high-antibody titer COVID-19 convalescent plasma reduces the risk for all-cause hospitalization among infected outpatients, particularly when receipt occurs within 5 days of symptom onset.

Between January 2020 and September 2022, researchers searched the medical literature for studies that assessed the efficacy of COVID-19 convalescent plasma in preventing all-cause hospitalization among adult outpatients with symptomatic COVID-19 infection. A total of 617 randomized controlled trials were identified, of which 5 were included in the meta-analysis. Patients were randomly assigned to receive either an intravenous transfusion of convalescent plasma or normal saline (control). The primary outcome was all-cause hospitalization within 28 days; the secondary outcome was all-cause hospitalization among patients who were hospitalized more than 24 hours following transfusion receipt.

The modified intention-to-treat population included 2620 patients, of whom 1562 (60%) were transfused within 5 days of symptom onset, and 159 (6%) were fully vaccinated.

Overall, 160 (12.2%) and 111 (8.5%) patients in the control and intervention groups were hospitalized, respectively. Further analysis indicated that convalescent plasma was associated with an absolute risk reduction (ARR) of 3.7% (95% CI, 1.3%-6.0%), a number needed to treat (NTT) of 27, and a relative risk reduction (RRR) of 30.1% (95% CI, 12.0%-44.4%) in regard to the risk for all-cause hospitalization.

In regard to the risk for all-cause hospitalization among patients who were transfused within 5 days of symptom onset vs those in the control group, the ARR was 5.8% (95% CI, 2.6%-9.0%), the NTT was 17, and the RRR was 39.5% (95% CI, 19.9%-54.3%).

Of note, the greatest risk reduction for all-cause hospitalization was observed among patients who received high-antibody titer transfusions within 5 days of symptom onset (RRR, 51.7%; 95% CI, 28.3%-67.1%).

Researchers noted that the predominance of unvaccinated patients limited the ability to analyze the effectiveness of COVID-19 convalescent plasma in reducing the risk for all-cause hospitalization in a primarily vaccinated population.

According to the researchers, “Future research should focus on defining the optimal antibody titer and dosage for CCP (COVID-19 convalescent plasma) and evaluating its effectiveness among immunocompromised vaccinated patients.” 

Disclosures: Multiple authors declared affiliations with pharmaceutical, biotech, and/or device companies. Please see the original reference for a full list of disclosures.

This article originally appeared on The Cardiology Advisor