Why has the FDA cleared convalescent plasma, a potential treatment for COVID-19?


The Trump administration’s announcement on Sunday of an emergency use authorization for convalescent plasma left critical questions about the potential COVID-19 treatment unanswered.

Which patients will benefit? When should doctors give the plasma? What is the correct dosage? And perhaps the most crucial: does it even work?

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Only randomized clinical trials, which compare a treatment to a placebo and are considered the gold standard of medical evidence, can provide answers. Now that the Food and Drug Administration has given permission for the emergency use of antibody-rich plasma, or EUA, will patients be motivated to participate in such trials, in which they might not receive the real plasma? ?

“Investigators had difficulty recruiting patients to begin with, and this announcement will make the task even more difficult, if not impossible,” said Dr. Howard Koh, professor at Harvard TH Chan School of Public Health who was under secretary. to health and humans. health services in the administration of President Barack Obama.

“It’s a disservice, actually,” Koh added.

In a live interview with the Journal of the American Medical Association, Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, said Monday, “The job of the FDA is to license and , in this case, to approve the products that have demonstrated its effectiveness and has been found to be safe. It is likely that the plasma, for the most part, has been found to be safe. But you have to show it works. If you look at the data, they haven’t proven it works. “

Convalescent plasma is the antibody-rich blood product taken from patients who have recovered from COVID-19. In theory, infusing a sick patient with the antibodies would boost the person’s immune system to fight the virus.

Studies have shown that convalescent plasma for COVID-19 is generally safe. And while other studies have hinted that the treatment is promising, they aren’t definitive answers on its effectiveness.

“Without the data from clinical trials, we won’t know if convalescent plasma is working,” Gregg Gonsalves, assistant professor of epidemiology at the Yale School of Medicine, wrote in an email. “That’s why we are experimenting, so as not to make mistakes. “

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Even the FDA guidelines for authorization recognized that more clinical trials are needed to determine if convalescent plasma is effective, and he added that treatment should not be considered a new standard of care for the patient. disease.

“Since the clinical evidence supporting this EUA has not been obtained from prospective and well-controlled randomized clinical trials (RCTs), additional RCTs are needed. Convalescent plasma should not be considered a new standard of care for treating patients with COVID-19, ”said the advice, which was obtained by NBC News.

However, in Sunday’s announcement, President Donald Trump and FDA Commissioner Dr Stephen Hahn took a different tone, saying the treatment reduced mortality by 35%.

The statistic comes from a preliminary study on convalescent plasma from the Mayo Clinic. It was published online on the medRxiv preprint server and has not been peer reviewed.

Among a subset of patients, those who received plasma with a higher level of COVID-19 antibodies were about one-third less likely to have died within seven days, compared to those who received plasma with a lower rate.

The study did not compare patients who received plasma with a control group who received placebo.

Still, Dr Michael Joyner of the Mayo Clinic, who heads the nation’s expanded access program, which has enabled more than 70,000 COVID-19 patients to receive recovering plasma, said the results “are certainly reaching the end of the spectrum. threshold ”for an emergency use authorization.

The FDA grants EUAs only during public health emergencies and allows temporary use of unapproved medical products. Apart from public health emergencies, medical products must go through the standard FDA approval process.

With an EUA for convalescent plasma, Joyner said, the program from the Mayo Clinic will be transferred to the FDA and federal regulators will oversee how it is distributed.

While the EUA is expected to reduce the paperwork that doctors have to fill out to get plasma for patients, that doesn’t necessarily mean that the plasma will be widely available or easily accessible.

First, the processing relies on the donors. Second, the EUA guidelines for physicians state that plasma must contain “high antibody titers,” which means high concentrations of COVID-19 antibodies. Not all plasma donors have high antibody titers.

It is not known what could happen with plasma donated with lower titers. Again, only randomized clinical trials would be able to answer this question.

Dr. Todd Rice, associate professor of medicine at Vanderbilt University Medical Center in Nashville, Tennessee, has been selected to lead a large-scale, federally-funded randomized controlled trial of convalescent plasma in patients hospitalized with COVID-19.

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“We have found that people who have more severe symptoms tend to have higher concentrations” of antibodies, Rice said. He said the trial, which is expected to recruit up to 1,000 patients, is expected to continue despite the EUA. But it’s unclear whether efficacy data for plasma as a treatment will be available until a vaccine is approved.

“The point is, our way out of this pandemic is through the vaccine,” Rice said. “The sooner we get a vaccine, the better off we will all be. “

But Sunday’s press conference also raised concerns among scientists about political pressure on the FDA to rush the approval of a vaccine.

“What you saw yesterday is that the FDA was intimidated by the President of the United States into approving something that they didn’t want to approve sooner because he wanted them to do so. ”Offit said.

Koh said, “We must demand the highest level of rigorous science to guide these decisions. The health of a world is at stake. ”

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