Convalescent Plasma Therapy Shows to be Safe, Efficacious in COVID-19 Patients

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.

The study results were published in The American Journal of Pathology.

"Our studies to date show the treatment is safe and, in a promising number of patients, effective," coauthor James Musser, MD, PhD, chair of the Department of Pathology and Genomic Medicine at Houston Methodist said. "While convalescent plasma therapy remains experimental and we have more research to do and data to collect, we now have more evidence than ever that this century-old plasma therapy has merit, is safe and can help reduce the death rate from this virus."

Houston Methodist hospitals enrolled 316 patients from March 28 to July 6. The patients were tracked after plasma transfusion and compared to a control group of similar COVID-19 patients who did not receive convalescent plasma. An observational propensity score-matched analysis was used to balance the characteristics of participants and allow for an objective interpretation of the results at this stage.

Houston Methodist investigators found that those treated early in their illness with donated plasma had the highest concentration of antibodies and were more likely to survive and recover than similar patients who were not treated with convalescent plasma.

Patients who were excluded from the study included those with a history of severe reactions to blood transfusions, those with underlying uncompensated and untreatable end-stage disease, and patients with fluid overload or other conditions that would increase the risk of plasma transfusion.

“This interim propensity score-matched analysis suggests that transfusion of high anti-RBD IgG titer COVID-19 convalescent plasma early in hospitalization reduces mortality in COVID-19 patients,” the investigators wrote.