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Convalescent Plasma Strikes Out As COVID-19 Treatment


More than half-a-million Americans have gotten an experimental treatment for COVID-19. It's called convalescent plasma. But a year into the pandemic, it is not clear who, if anyone, actually benefits from it. And that highlights the challenges scientists have faced in studying COVID drugs. NPR science correspondent Richard Harris reports.

RICHARD HARRIS, BYLINE: On paper, treatment with convalescent plasma makes good sense. The idea is to take blood plasma from people who have recovered from COVID-19 and infuse it into people currently infected. The antibodies in that plasma, in theory, would help fight the virus. So based on that idea, Dr. Nicole Bouvier at the Icahn School of Medicine at Mount Sinai Hospital in New York decided to give it a try last March.

NICOLE BOUVIER: You know, we had this new disease that didn't have any known therapies, and convalescent plasma has been used in new epidemic and pandemic diseases, like as recently as Ebola.

HARRIS: She says she was the first doctor to get special permission from the Food and Drug Administration to use an experimental protocol. It was a huge commitment to line up people willing to donate plasma, as well as to treat patients themselves.

BOUVIER: So it was a big production. We ultimately screened over 70,000 people and identified around 20,000 who had high antibody titers.

HARRIS: She treated more than 1,400 patients right through New York's nightmare COVID outbreak last spring, but all the while, she had no idea whether the plasma really worked. Finally, a couple of weeks ago, she had seen enough data from carefully controlled studies and decided to stop offering the treatment.

BOUVIER: The straw that broke the camel's back was two very large cohort trials - RECOVERY in England and then CONCOR, which is a Canadian study.

HARRIS: The scientists running those studies said they were giving up because they simply weren't seeing signs that it could be useful. But those studies focused on people sick enough to be in the hospital. Dr. Arturo Casadevall at the Johns Hopkins School of Public Health is one of the prime advocates for convalescent plasma. He says he thinks the treatment needs to be done sooner in the outpatient setting.

ARTURO CASADEVALL: From the very beginning here at Hopkins, we set out to do outpatient trials. The trials were set up in March. However, it took many months to get the money to do it.

HARRIS: And a year later, they still don't have results. And it's not just funding. The entire U.S. medical research system isn't set up to do what's needed. Dr. Derek Angus at the University of Pittsburgh says, in a pandemic, we need to evaluate new treatments at hundreds of hospitals in a matter of months.

DEREK ANGUS: People might roll their eyes and say that's impossible, but that's largely what the United Kingdom has done.

HARRIS: The U.K. study of convalescent plasma, for example, ended up studying more than 10,000 patients to reach its conclusion. That was possible because Britain has a national health system, which not only provides treatment but can conduct research. Research in the United States is balkanized between universities, drug companies and funders, Angus says.

ANGUS: We pride ourselves on having a very federated, independent system. But gosh, that is very hard to turn on a dime to solve national problems.

HARRIS: To give just one example, a national network of emergency room physicians got federal funding to treat people with convalescent plasma. Their patients were sick enough to show up in the emergency room but well enough to go home afterwards.

KEVIN SCHULMAN: We should have been able to get this done as quickly as they did in the U.K. And it was just a much slower process to set up.

HARRIS: Dr. Kevin Schulman at Stanford was responsible for some of the logistics. And they were a nightmare.

SCHULMAN: I said tongue-in-cheek at some point, when we had five patients in our study, that we had at least 500 people touch a piece of paper for the five patients we had recruited. And that's the opposite in the U.K.

HARRIS: That emergency room study, too, was just stopped after about 500 patients had been recruited because continuing it would have been futile. This further casts doubt on the value of convalescent plasma, says Derek Angus from Pitt.

ANGUS: I don't see any point in offering plasma outside a clinical trial.

HARRIS: Several are still ongoing, and there's still a chance that some of them could identify a group of patients, treated at a particular time with a particular concentration of plasma, who would benefit. So Dr. Bouvier at Mount Sinai hasn't given up on it completely.

BOUVIER: If a study comes along that identifies a population in whom convalescent plasma is useful, we will use it in that population.

HARRIS: And if it does appear to be useful for people who are early in the course of disease, that raises another question - would plasma be better than the monoclonal antibody drugs already authorized for that purpose? Unfortunately, it could require another time-consuming study to figure that out.

Richard Harris, NPR News. Transcript provided by NPR, Copyright NPR.

Award-winning journalist Richard Harris has reported on a wide range of topics in science, medicine and the environment since he joined NPR in 1986. In early 2014, his focus shifted from an emphasis on climate change and the environment to biomedical research.