Clinicians at Houston Methodist are reporting that transfusing critically ill COVID-19 patients with high antibody plasma early in their illness—within 72 hours after hospitalization proving most effective—reduced the mortality rate.

They transfused 316 patients, and a preliminary analysis showed a significant reduction (P = 0.047) in mortality within 28 days, specifically in patients transfused with an anti-spike protein receptor binding domain titer of ≥1:1350 within 72 hours of their admission with plasma.

Of the 316 transfused patients, 136 met a 28-day outcome and were matched to 251 non-transfused control COVID-19 patients.

https://www.contagionlive.com/view/convalescent-plasma-therapy-shows-to-be-safe-efficacious-in-covid19-patients