Statement on NIH Study Testing Convalescent Plasma in Hospitalized Patients

Overall results show no benefit over placebo in delivering clinical improvement

January 11, 2022

For people hospitalized with COVID-19, convalescent plasma taken from those who had recovered was not more effective than placebo in delivering clinical improvement 14 days and 28 days after treatment began.

These findings are from a large Phase 3, randomized, placebo-controlled clinical trial funded by the National Institutes of Health (NIH). The Convalescent Plasma to Limit COVID-19 Complications in Hospitalized Patients (CONTAIN COVID-19) trial included data from 941 participants enrolled between April 2020 and March 2021 at 21 hospitals in Connecticut, Florida, Maryland, New York, Texas and Wisconsin. The primary outcome was clinical status based on the participant scores on the 11-point World Health Organization (WHO) Ordinal Scale for Clinical Improvement 14 days after randomization. The secondary outcome was clinical status on the same scale 28 days after randomization.

Eligible participants in CONTAIN COVID-19 were adults 18 years or older who tested positive for SARS-CoV-2 infection, had been hospitalized for no more than three days or had experienced respiratory illness symptoms for no more than seven days and required noninvasive supplemental oxygen while hospitalized.

While convalescent plasma did not meet the trial’s primary and secondary outcomes for clinical improvement, the researchers conducted additional statistical analyses because patient characteristics and COVID-19 treatments changed over the course of the 11‑month study. They sought to understand the effect of changes on convalescent plasma efficacy at different time points of trial enrollment. The results indicated possible clinical benefit in the early stage of the pandemic (April to June 2020), when participants received high-titer convalescent plasma without corticosteroids and remdesivir. During that period, patients receiving convalescent plasma were more likely to clear COVID-19 symptoms, be discharged from the hospital earlier and/or require less supplemental oxygen.

Among the large, placebo-controlled study’s strengths was the highly diverse participant pool, which may make CONTAIN COVID-19’s findings generalizable across multiple population groups — 41% of study volunteers were female, 40% were Hispanic and 14% were non-Hispanic Black. The trial’s innovative statistical design also allowed near real-time monitoring of patient treatment information and faster assessment of therapeutic efficacy.

Liise-anne Pirofski, M.D., and Hyunah Yoon, M.D., of Albert Einstein College of Medicine and Montefiore Medical Center, and Mila B. Ortigoza, M.D., Ph.D., of New York University Langone Health, led the multisite clinical trial. The study’s findings appear in JAMA Internal Medicine. NCATS oversaw the trial through its Clinical and Translational Science Awards Program research network.

View the NIH COVID-19 Treatment Guidelines for additional information on convalescent plasma.