The Food and Drug Administration is reducing its authorization for the use of convalescent blood plasma for patients with Covid-19 in an effort to guide physicians who have faced a confusing set of data on the effectiveness of therapy .
The agency said Thursday afternoon that the authorization, which has been the subject of controversy since it was first published last August, would be reviewed to limit plasma use to hospitalized patients early in the course of the trial. disease and in hospitalized patients with a disease that affects their ability to make antibodies. Patients will be allowed to receive only plasma containing high concentrations of antibodies.
“The upgrade is designed so that convalescent plasma can be better used in those who will benefit from it,” said Peter Marks, director of the FDA’s Center for Biological Evaluation and Research. “It is being used more indiscriminately.”
Dr. Claudia Cohn, chief physician at AABB, an organization representing the transfusion medicine community, said the group plans to issue interim recommendations on convalescent plasma later this month. “There are so many studies that come out with different conclusions,” he said. “It’s not clean, it’s not black and white.”
Dr. Marks said the FDA made its decision after evaluating the results of several recent studies. Some showed benefits of convalescent plasma, the fluid that contains antibodies derived from the blood of people who have recovered from Covid-19. Others showed no benefit.
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Two clinical trials of convalescent plasma for hospitalized patients closed last month after researchers said there appeared to be no benefit. Three trials with recently hospitalized patients reported some benefit to plasma, but only when it was given to patients shortly after admission. Yet another trial showed that elderly outpatients with plasma shortly after showing symptoms were less likely to develop serious illness.
Arturo Casadevall, president of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, described the FDA’s decision as a “step forward.” He said, “Doctors in the United States for the first time will have instructions on when to use it and how to use it” convalescent plasma.
Dr. Casadevall is a co-founder of the Covid-19 Convalescent Plasma Project, which helped organize a nationwide expanded access study of convalescent plasma that began last April.
Despite conflicting findings, convalescent plasma remains in demand, in part because there are few effective treatments for Covid-19 and many people remain unvaccinated. Since the FDA issued the emergency clearance last August, the blood industry has distributed an average of about 20,600 units of convalescent plasma a week to hospitals across the country, according to the American Red Cross.
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The FDA’s previous decision to authorize convalescent plasma for hospitalized Covid-19 patients was largely based on the results of an agency-sponsored expanded access program, through which more than 72,000 patients they received plasma. For a study published last month in the New England Journal of Medicine, researchers analyzed data from 3,000 of these patients and reported an apparent survival benefit among hospitalized patients who lacked mechanical ventilation and who received plasma with high concentrations of antibodies.
But many scientists expressed skepticism about the finding, saying extended access studies lack the scientific rigor of traditional trials because they have no control group to compare any apparent effect.
FDA’s Dr. Marks said the convalescent plasma clearance “could have been handled much better. It had to do with the sense of urgency that everyone feels. I can’t blame anyone for feeling a sense of urgency.”
Dr. Marks also said the data could be confusing. Each unit of convalescent plasma is unique, reflecting the immune response of the recovered patient who gave it. It took time to figure out the best way to measure antibodies in a unit, he added.
The United States is not the only government trying to establish reliable guidelines on the use of convalescent plasma. In Argentina, a study of outpatients in the elderly published last month in the New England Journal of Medicine contributed to current recommendations for treating elderly patients with covid-19 at the onset of their disease. “Plasma supplies are not endless and public health officials invariably face difficult decisions,” said Dr. Fernando Polack, co-author of the study, of the Infant Foundation of Buenos Aires. “In any of these decisions, data-driven guidelines are needed and they are the best way for doctors to feel comfortable when faced with individual cases.”
Donors donating blood and plasma at a donation center in Brooklyn, New York
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Louis M. Katz, chief physician at the Mississippi Valley Regional Blood Center in Davenport, Iowa, which provides blood products for more than 120 hospitals, said evidence supporting the use of convalescent plasma in hospitalized patients is weak. “I think there is data that will work soon,” he said. “As it moves to more and more sick people, the tests get thinner and thinner.”
In an editorial accompanying the New England Journal of Medicine on the U.S. Extended Access Study, Dr. Katz said convalescent plasma should only be used in patients at the onset of the disease. The problem with this suggestion, he added later, is that the FDA’s emergency use authorization still only covers hospitalized patients, who tend to show up at the hospital when they’ve been sick the longest.
Treatment of Covid-19 patients who are just beginning to show symptoms presents its own challenges. “Logistically, it’s very difficult to treat patients before,” Dr. Katz said. “It’s hard to transfuse a lot of plasma into outpatients.”
Dr. Marks said a large study by the National Institutes of Health is now being conducted to test for convalescent plasma in people with Covid-19 who are sick enough to come to the emergency room but are not hospitalized, as well. other randomized controlled trials of plasma in outpatients. “Until we have this data, we will retain the authorization to hospitalized patients,” he said. “We will refine it if necessary. This is a scarce resource. “
Write to Amy Dockser Marcus at [email protected]
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