Axfors C, Janiaud P, Schmitt AM, et al. - Using data from all available randomized clinical trials, including unpublished and ongoing trials, researchers herein investigated the benefits of convalescent plasma treatment relative to placebo or no treatment and all-cause mortality in patients with COVID-19.

• Collaborative systematic review and meta-analysis.

• Clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed yielded data of a total of 16,477 patients included in 33 trials (20 unpublished with 3,190 patients, 13 published with 13,287 patients) for inclusion.

• Death was recorded for 1,997 of 8,495 patients (23%) who received convalescent plasma, and for 1,952 of 7,982 control patients (24%).

• There appeared no correlation of using convalescent plasma treatment with reduced all-cause mortality among patients with COVID-19.

• Herein, strong evidence has been generated against using convalescent plasma treatment for patients with COVID-19 outside of randomized trials.