Convalescent plasma is not proven to treat COVID-19, an NIH panel said Tuesday, undermining an emergency authorization issued by the FDA a week ago.
The panel of experts convened by the NIH said that there is “insufficient data” to show whether plasma is a safe, effective treatment, contradicting misleading claims that President Donald Trump and two top health officials recently made about plasma’s benefits. Trump’s remarks — in part that “the FDA has made the independent determination that the treatment is safe and very effective” — have led scientists to accuse the agency of buckling under a White House that wants to push the narrative that it is controlling the pandemic.
Coronavirus survivors’ plasma — the liquid in blood that is left over when blood cells are removed — has raised hopes that its antibodies could offer other patients protection against the virus. On Aug. 23, when the FDA authorized convalescent plasma for hospitalized patients, Trump claimed that a Mayo Clinic study showed it “has proven to reduce mortality by 35%.” Health and Human Services Secretary Alex Azar said, “I don’t want you to gloss over this number.”
And FDA Commissioner Stephen Hahn said that out of “100 people who are sick with COVID-19, 35 would have been saved because of the admission of plasma.”
That wasn’t what the study showed, however, or even what the FDA had initially said in its press release announcing the authorization. The agency had only said that plasma “may be effective” and that “the known and potential benefits of the product outweigh the known and potential risks of the product.”
The officials’ remarks were met with searing criticism from the scientific community. Cardiologist Eric Topol urged Hahn this week to “tell the truth or resign,” calling his remarks a “major breach of accurate, science-based information.”
Hahn’s statement may have given the impression that people who received plasma were 35% more likely to be saved, compared to people who did not receive plasma. That is how a randomized controlled trial, which is considered the gold standard in medicine, would be set up.
But the Mayo study — which has not yet been peer-reviewed or published — did not have a control group that received a placebo. Instead, it gave plasma to more than 35,000 patients and reported on what happened.
As the FDA later clarified in a statement, patients who received plasma with higher antibody levels had “roughly a 35 percent relative improvement” in survival rates, compared to those who received plasma with lower levels. In other words, the 35% figure measured relative risk, not absolute risk. Another caveat: This data only applied to a subset of patients under age 80 who weren’t on ventilators.
Hahn has since apologized for his comments. “The criticism is entirely justified,” he wrote on Twitter. And the FDA later updated its press release with a graphic depicting a “37% reduction in mortality” in those who received plasma with a high concentration of antibodies.
As the NIH panel pointed out Tuesday, there is “currently no data from well-controlled, adequately powered randomized clinical trials” showing if convalescent plasma works.
“There are insufficient data to recommend either for or against the use of convalescent plasma for the treatment of COVID-19,” the panel added.
Scientists have been calling for randomized clinical trials. “We don’t know if it’s safe and effective if it’s not a decision based on randomized controlled data. Period. End of story,” Steven Nissen, chief academic officer of the Heart and Vascular Institute at the Cleveland Clinic, told BuzzFeed News at the time of the press conference.
But trials have had trouble recruiting people who are unwilling to take the risk of receiving a placebo. The FDA’s emergency authorization, critics say, is likely to make it even harder for those trials to find volunteers.
The FDA did not immediately respond to a request for comment.