En español | The U.S. Food and Drug Administration (FDA) announced Sunday it will now allow emergency use of “convalescent plasma therapy” for hospitalized coronavirus patients — a move that brought hope while it stirred debate.
The treatment, which involves the injection of the liquid component of blood that contains antibodies from those who have recovered from the coronavirus, is thought to be fairly safe. Early results of a study from the Mayo Clinic showed it could, under certain limited circumstances, boost the body’s immune system to fight the virus — if given early enough.
However, that study is still underway, and the data released so far does not meet the widely established standard of a double-blind, peer-reviewed investigation involving a placebo control group, as the Mayo researchers themselves readily acknowledged. Specifically, they reported that the seven-day mortality rate among 35,000 mostly critically ill patients who were transfused with the therapy within three days of being diagnosed with COVID-19 was lower (8.7 percent) than for patients transfused with the therapy four days after diagnosis (11.9 percent).
News of the treatment’s emergency approval — which reversed an earlier decision — comes as a large, nationwide, rigorous scientific trial is underway to compare the safety and efficacy of convalescent plasma therapy versus a placebo among adults exposed to COVID-19. The double-blind study is being sponsored by the National Institutes of Health in Bethesda, Maryland, and the Department of Defense.
“I think what we know so far is that using convalescent plasma is safe for the people with COVID-19 who receive it, in general,” said Edward “Lalo” Cachay, professor of medicine in the infectious disease department at the University of California, San Diego, School of Medicine, which is one of the trial sites. “Can we with precision and accuracy say it is effective? Is it safe for people who are seriously ill? We don’t have the data. We don’t know.”
Cachay was one of many policy and science experts characterizing the FDA’s emergency use approval yesterday as premature, saying that results from the smaller studies released so far show effects that are “marginal at best” and that questions about the time-intensive treatment’s effectiveness remain. “We need larger trials that are ongoing to answer the questions. I hope this decision does not affect them,” he said.
He added that President Donald Trump’s calling convalescent plasma therapy a major breakthrough “does not seem to be supported by current evidence,” and noted that the FDA approved similar emergency use for hydroxychloroquine — only to reverse it when the treatment later proved unsuccessful in patients.
Shiv Pillai, professor of medicine at Harvard Medical School, noted that more research is also needed to suss out the basic mechanism at work with the plasma treatment. He said plasma therapy is widely used for a lot of diseases, especially inflammatory diseases like COVID-19: “It is completely possible that what little effect seen [is] just from the presence of plasma, and it might work if it didn’t contain the antibodies of someone who had coronavirus.” Clinical trials, he said, would provide the data to conclude if the treatment actually targets COVID-19 or if the results seen so far were “just a random effect of immunoglobulins.”
Nicole Bouvier, associate professor in the division of infectious diseases at the Icahn School of Medicine at Mount Sinai, echoed the scientific consensus that more research is needed. “We’re trying to build a wall of evidence and we’re putting down pebbles,” she said. What’s more, she worries about there being enough plasma to go around now, since each plasma treatment — to be studied, or to be used on a patient — requires blood donations from recovered patients.
The use of convalescent plasma isn’t new; it was used during the Spanish flu pandemic in an effort to save lives. In addition to small trials here, it’s been studied in COVID-19 patients in China and the Netherlands.