Can Plasma From Recovered Covid-19 Patients Cure Infected Others?
US Food and Drug Administration (FDA) officials announced today they have approved plans for nationwide trials of two treatments for Covid-19, the global pandemic disease caused by the new coronavirus—and for their simultaneous use in perhaps hundreds of hospitals.
The therapeutic agents—convalescent plasma and hyperimmune globulin—are both derived from the blood of people who have recovered from the disease, decoctions of the antibodies that the human immune system makes to fight off germs.
“This is an important area of research—the use of products made from a recovered patient’s blood to potentially treat Covid-19,” said FDA commissioner Stephen Hahn in a release announcing the trials. “The FDA had played a key role in organizing a partnership between industry, academic institutions, and government agencies to facilitate expanded access to convalescent plasma. This is certainly a great example of how we can all come together to take swift action to help the American people during a crisis.”
Physicians are already using a somewhat haphazard collection of antiviral and other drugs for people critically ill with Covid-19, because they don’t have any other options. Nothing—no drug, no vaccine—is approved for use specifically against Covid-19 in the United States, so any new possibility is a hopeful one. Convalescent plasma and hyperimmune globulin join the rarified group of therapeutics that scientists are testing, including a trial of the Ebola drug remdesivir and the much-hyped antimalarial/immune suppressants chloroquine and hydroxychloroquine.
Using blood products from people who’ve already beaten a disease is a century-old approach, predating vaccines and antibiotics. Inspired by its use against polio, two physicians at a Naval hospital in Massachusetts tried it on people who had pneumonia as a result of influenza in 1918, with enough success to warrant more tests. The quality of actual studies of efficacy has varied over the decades, but health care workers used convalescent plasma against SARS, MERS, and Ebola. And a couple of studies—small and preliminary—have shown convalescent plasma having some promise against SARS-CoV-2 as well.
At Houston Methodist Hospital, James Musser, the chair of Pathology and Genome Medicine, is a friend of Arturo Casadevall, the Johns Hopkins University immunologist who proposed using convalescent serum early in the pandemic. Musser pushed to get his hospital involved, putting out a call for donors—people who had confirmed positive tests for the virus and had gone at least 14 days without symptoms. His hospital is already doing compassionate-use transfusions. “So far, as of yesterday, we’ve transfused four patients,” Musser said on Thursday. He expected a fifth to receive plasma today. And how’d it work? “The truth is, it’s far too early,” Musser says. “We, nationally, need to do controlled trials and understand, first and foremost, is this a safe therapeutic? There’s lots of reasons to think it will be, but you never know.”