No benefit of convalescent plasma in patients with severe COVID-19 pneumonia: study

Study results published in the NEJM suggest that patients with severe COVID-19 pneumonia who received treatment with convalescent plasma had no significant improvements in clinical status or overall mortality compared to those administered placebo. The results echo those reported from another trial in October, which showed that using convalescent plasma alongside best standard of care in hospitalised patients with moderate COVID-19 had "limited effectiveness" at stopping progression to severe disease or reducing mortality.

The latest study, dubbed PLASM-AR, included 333 hospitalised adults with severe COVID-19 pneumonia, with 228 randomised to receive a single administration of convalescent plasma and the remaining 105 assigned to be given placebo. The trial's primary outcome was the patient's clinical status 30 days after the intervention, as measured on a six-point ordinal scale ranging from total recovery to death.

Results showed that at day 30, no significant difference was seen between the convalescent plasma group and the placebo arm in the distribution of clinical outcomes according to the ordinal scale, while there were no significant differences at days seven and 14 either. Meanwhile, 30-day mortality rates were 10.96% and 11.43% for the two groups, respectively.

Findings also showed that the median time from enrolment to hospital discharge was 13 days in the convalescent plasma group, versus 12 days in the placebo arm. Further, throughout the trial, the proportion of ICU admissions and invasive ventilatory support requirements was 53.9% and 26.8%, respectively, in the convalescent plasma group, and 60% and 22.9%, respectively, for placebo. In addition, no significant differences were seen in the time to death or in the time to clinical improvement of at least two categories on the ordinal scale or hospital discharge.

Commenting on the findings, study leader Ventura Simonovich said that convalescent plasma might still help mild-to-moderate cases of COVID-19, although more studies would be needed to investigate this. However, Simonovich suggested that for patients with severe disease, like the study population, "other therapies based on antibodies could have a role."

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