"Unfortunately, it was either being administered outside of clinical trials or in trials that weren't focused on critically ill patients, slowing our ability to see if it actually worked," McVerry said.
Convalescent plasma therapy is “futile” as a treatment for most critically ill COVID-19 patients, according to a study published on Tuesday. The findings, published in the journal JAMA, are the latest from REMAP-CAP trial, which has enrolled thousands of patients in hundreds of hospitals globally to quickly determine what COVID-19 treatments work best in which patients.
“There were biologically plausible reasons to turn to convalescent plasma early in the pandemic when hundreds of thousands of people were getting sick and treatments had yet to be discovered,” said study co-lead author Bryan McVerry, an associate professor at the University of Pittsburgh School of Medicine (UPMC) in the US.
“Unfortunately, it was either being administered outside of clinical trials or in trials that weren’t focused on critically ill patients, slowing our ability to see if it actually worked,” McVerry said.
With these latest results, the researchers said using convalescent plasma should be stopped for treating sickest COVID-19 patients. Focus should be on treatments that are known to work, as well as developing and testing better ones, they said. In the convalescent plasma trial, REMAP-CAP enrolled 2,011 adults hospitalised with severe COVID-19. They were randomised to either receive two units of convalescent plasma or no plasma.
The participants were followed to see if the likelihood of surviving at least three weeks without needing organ support, such as a ventilator, differed based on whether they were treated or not. The trial collected enough data to conclude with greater than 99 per cent certainty that convalescent plasma did not help critically ill COVID-19 patients, according to the researchers.
However, the results followed a slightly different pattern for the 126 patients who were immunocompromised, the researchers said. This group appeared to do slightly better with the convalescent plasma treatment compared to the standard treatment, but the number of patients was too small to make a definitive statement, they said.
Lise Estcourt, an associate professor at the University of Oxford, UK noted that the reason could be that patients who are unable to mount an effective immune response could still benefit from the antibodies present in blood plasma from COVID-recovered patients, especially early on in the illness. “This is something that definitely warrants investigation, said Estcourt, the corresponding author of the study.
The researchers could not determine why convalescent plasma did not improve outcomes in most critically ill patients. “We speculate that it could be a combination of too few high-quality antibodies in the plasma and these patients being too far along in their illness with a run-away inflammatory immune response for those antibodies to turn the tide,” said study co-senior author Derek Angus from UPMC.
“It is still possible that convalescent plasma helps people in earlier stages of illness, though it is likely not efficient to use given that monoclonal antibodies are such an effective treatment for early COVID-19,” Angus added.