FDA issues emergency authorisation for convalescent plasma in COVID-19 amid uncertainty over benefits

The FDA issued an emergency-use authorisation (EUA) for convalescent plasma as a potential treatment for COVID-19 in hospitalised patients, saying the "known and potential benefits of the product outweigh the known and potential risks." The agency said its action follows an "extensive review of the science and data generated over the past several months" amid efforts to facilitate access to convalescent plasma as clinical trials looking to "definitively demonstrate" whether the experimental therapy is safe and effective, remain ongoing.

The move came after President Donald Trump criticised the FDA in a tweet over the weekend, suggesting some people at the agency were "making it very difficult for drug companies to get people in order to test the vaccines and therapeutics," and that these individuals were "obviously…hoping to delay the answer" until after the US elections on November 3. "Must focus on speed, and saving lives!" Trump tweeted.

Some officials say data weak

A recent report indicated that the FDA was preparing to issue an EUA for use of blood plasma to treat COVID-19, but that the move was put on hold after a group of health officials intervened, arguing that emerging data on the treatment were too weak. According to the report, the officials included Francis Collins, director of the US National Institutes of Health, and Anthony Fauci, who heads the NIH's National Institute of Allergy and Infectious Diseases. The report said they argued that recent data from the country's largest plasma study, run by the Mayo Clinic, was not strong enough.

Health and Human Services Secretary Alex Azar indicated that convalescent plasma has "reached more than 70,000 American patients so far." Earlier this month, positive study results were posted to the medRxiv preprint server from the Mayo Clinic and its collaborators based on a cohort of 35,322 transfused patients, of whom 52.3% were in the intensive care unit and 27.5% were receiving mechanical ventilation at the time of plasma transfusion.

Specifically, researchers found that the seven-day mortality rate was 8.7% in patients transfused within three days of COVID-19 diagnosis, compared with 11.9% in those transfused four or more days after. Similar findings were observed in 30-day mortality, with rates of 21.6% versus 26.7%, respectively. Further, convalescent plasma with higher IgG antibody levels was associated with reduced seven-day mortality. For patients who received IgG plasma greater than 18.45 S/Co, seven-day mortality was 8.9%, whereas for recipients of medium IgG plasma, ranging from 4.62 S/Co to 18.45 S/Co, mortality was 11.6%, and for recipients of IgG plasma less than 4.62 S/Co, mortality was 13.7%. Researchers noted that this unadjusted dose-response relationship with IgG was also observed at the 30-day mark.

Not a new standard of treatment

Still, in a letter describing the EUA, Denise Hinton, chief scientist for the FDA, stated that "convalescent plasma should not be considered a new standard of care for the treatment of patients with COVID-19. Additional data will be forthcoming from other analyses and ongoing, well-controlled clinical trials in the coming months."

Meanwhile, White House chief of staff Mark Meadows remarked that "this president is about cutting red tape." Meadows said "we've looked at a number of people that are not being as diligent as they should be in terms of getting to the bottom of it…[Trump] had to make sure that they felt the heat. If they don't see the light, they need to feel the heat because the American people are suffering."

However, Joshua Sharfstein, a vice dean at John Hopkins University's school of public health who was a top FDA official during the Obama administration, rejected the suggestion that some at the FDA were holding up the emergency authorisation for political reasons. "This is a promising therapy that has not been fully established," he said.

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