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WASHINGTON — The Food and Drug Administration on Sunday issued an emergency authorization for doctors to treat Covid-19 using blood plasma from patients who’ve recovered from the disease.

Below, STAT answers the major questions surrounding convalescent plasma as a Covid-19 treatment and the science supporting its use.

What is convalescent plasma, and how does it work?

When people get sick with Covid-19, their immune systems generate antibodies to fight the disease. Those antibody proteins float in their blood plasma — the liquid component of blood that suspends blood cells.   


Doctors can harvest the plasma, test it for safety, and then purify it to isolate those antibodies. That “plasma-derived therapy,” or “convalescent plasma,” can be injected into another patient sick with Covid-19, and the antibodies it contains can help fight the virus early in an infection until the patient’s own immune system generates its own antibodies in sufficient quantities to beat back Covid-19.

Does scientific evidence show that convalescent plasma is a safe and effective treatment for Covid-19?

The Mayo Clinic released data in June that showed plasma treatment was safe following transfusion in a group of 20,000 patients, which included substantial enrollment from Black and Latino patients.


A study released Aug. 13 — but not yet peer-reviewed — suggested that using convalescent plasma to treat patients with severe Covid-19 soon after their diagnosis was associated with a lower likelihood of death. But the study had serious scientific limitations that make interpreting the findings difficult.

The Mayo Clinic study, which enrolled more than 35,000 patients, showed that patients who received transfusions within three days of their Covid-19 diagnosis had a seven-day death rate of 8.7%, while patients who received plasma treatment after four or more days had a mortality rate of 11.9%. The difference met the standard for statistical significance.

The study didn’t include a placebo group for comparison, however, so it’s unclear exactly how impactful the plasma treatment might be. The study was sponsored by the National Institutes of Health and sought to broaden access to convalescent plasma, part of a so-called “expanded access” program not designed to definitively test how well the treatment works, but instead to quickly get it to patients.

More rigorous randomized, placebo-controlled studies of convalescent plasma are ongoing.

What does an emergency use authorization, or “EUA,” mean?

The FDA has issued a number of emergency authorizations for Covid-19 treatments: Most notably the Gilead Sciences antiviral remdesivir, and for the antimalarial drug hydroxychloroquine, which the agency has since withdrawn.

The authorizations mean, effectively, that the agency believes the treatments in question are promising and largely safe, though there’s not yet definitive data supporting their efficacy.

An EUA for convalescent plasma would effectively license doctors across the country to begin treating Covid-19 patients with convalescent plasma, but it’s unclear whether it will result in a meaningful expansion in access to the therapy, in part because the supply is limited by the number of recovered patients who donate plasma.

The Mayo Clinic study, which relied on an FDA “expanded access” program, was broad enough that it allowed 35,000 patients access to the treatment despite the lack of a formal authorization for its use. It’s unclear whether an EUA will lead to a major increase in the number of doctors capable of using convalescent plasma to treat Covid-19, and the number of patients who will end up receiving the treatment.

Aren’t some patients being treated with convalescent plasma already?

Yes, through “compassionate use” programs like the Mayo Clinic study, and through more rigorous clinical trials.

Isn’t the government already advertising convalescent plasma as a Covid-19 treatment?

Yes. FDA Commissioner Stephen Hahn began encouraging Americans sick with Covid-19 to donate plasma as early as April. The federal government, in fact, has already spent about $8 million on radio and online advertisements encouraging Americans to donate plasma, even though no government agency has formally endorsed its use.

Trump attended a roundtable on donating plasma last month at the American Red Cross national headquarters in Washington, D.C., accompanied by health secretary Alex Azar, Surgeon General Jerome Adams, and Tony Fauci, the director of the National Institute of Allergy and Infectious Diseases.

Hahn’s face has even appeared on FDA-branded billboard advertisements that encourage passers-by: “Help us save lives. Donate plasma now.”

Has there been pushback regarding use of convalescent plasma?

Yes. The New York Times reported on Wednesday that Fauci and the director of the National Institutes of Health recently intervened to discourage the FDA from issuing an EUA for convalescent plasma, citing concerns over weak data.

It’s not clear whether their reported pushback made a difference. Francis Collins, the NIH director, and Fauci are widely respected scientists but have no authority over FDA.

Scientists outside government have cast the convalescent plasma debate as a case study in pandemic-era science — and how the urgency of treating Covid-19 balances against the need for caution and due diligence in developing new medical treatments.

“It raises the question of what strength of evidence is necessary to treat during a pandemic,” Harlan Krumholz, director of the Center for Outcomes Research and Evaluation at Yale New Haven Hospital, told STAT recently. “The problem is we have yet to resolve what is sufficient evidence to change the treatment paradigm.”

  • I applaud you for your very good Article. You have managed to restore some of my confidence in Journalist. This Therapeutic potential has a Glimmer of Hope the world desperately needs. I don’t need to read once again about Fauci running his mouth why a Doctor shouldn’t try this with a Covid-19 patient that will be dead in a week if nothing else is done. So Again Great Article. Thank You.

  • Please send me more information regarding the clinical trials and chances of getting this convalescent treatment anywhere, not just at selected hospital treatment studies locations.

  • I guess dear Abbie did not notice that the author of the Newsweek “opinion piece” is an MD and holds a Ph d. He teaches at Yale School of Public Health and as he points out, usually publishes in peer reviewed medical journals. It is by publishing in general reader magazines like Newsweek that he may bring unbiased information to that general reader such as dear Annie.

    • stop already! Not another go-around with the loony hydroxychloroquine BS. Lhfry are you a Qanon fan by any chance? STAT is presumably a platform for people interested in SCIENCE and biomedicine. Just an FYI that was an Opinion piece in newsweek, and full of BS. The issue is that CP needs to be rigorously tested, so it doesn’t end up like the hydroxychloroquine shit-show.

  • The article was very informative, yet somewhat worrisome having the Federal Government push medical knowledge and research aside for expediency.

  • The Washington Post has an OpEd from Jeremy Samuel Faust that includes so much more important information than this article. “So far, there have been two clinical trials studying plasma for covid-19. Of the two, one has been published in a medical journal. It disappointingly showed no improvement in patients given plasma in China.

    But perhaps the second study, which remains unpublished by a medical journal, provides the most insight. Researchers in the Netherlands halted the trial early. Why? Because they measured the antibody concentrations not just of the donor plasma, but of the recipients. They found something surprising. Most of the covid-19 patients in the throes of the illness already had high levels of these antibodies. This is an important insight into why plasma transfusions have failed for so many illnesses in the past, such as Ebola. If plasma is akin to bringing a knife to a gunfight, adding a few more knives will not suffice.” “The FDA cited such data when it claimed a 35 percent reduction in deaths among a small subset of patients under age 80 who both received plasma within three days, and who did not require mechanical ventilation. This is the very definition of cherry-picking. To hail this observation as a breakthrough, in the absence of a true clinical trial, is inappropriate.””Plasma transfusions of all kinds have a well-documented rate of serious adverse events. These events include lung damage and even life-threatening anaphylaxis. Transfusions can cause an array of immune reactions, some welcome and some not, depending on the context. Given that covid-19 is in part driven by an autoimmune reaction to the novel coronavirus, more study is essential before doctors proceed with the plasma treatment. Some data are already available. In a recent study of plasma in covid-19 patients, 25 serious reactions occurred among 5,000 transfusions. That’s 1 in 200. Four people died. Though it is hard to know if these deaths were directly or indirectly related to plasma, they must be taken seriously.” “The difference here is that plasma might actually work in some patients. We need to know who the right patients are and whether early treatment works. We need to know if some components of plasma help while others cause harm. An FDA emergency-use authorization makes it harder for clinical trials already underway to make progress because recruiting volunteers is harder when patients think the science is settled.

    The science isn’t settled. Only medical experts, not elected officials, can make the call on what constitutes safe and effective covid-19 treatments. The impulse to say we can’t afford to wait is understandable. But the truth is, we can’t afford to rush.” enough said. Can the quacks stop posting here please?

  • Gross exaggeration, factual distortions, hyperbole, and blatant lies are Donnie’s trademarks, so it’s no surprise that he would claim that a treatment with modest potential — made available through arm-twisting of the FDA — is a “game-changing breakthrough”, i.e., it’s little more than a Hail Mary for his struggling reelection campaign.

    • Struggling? Rasmussen was one of only two polls that got 2016 right and they currently have Trump within the margin of error in the important swing states. Go look at the actual data behind most of the polling showing Trump doing poorly, they greatly oversample democrats.

  • We need every Covid-19 treatment to save lives. This is a type of treatment which has been proven by this and use on thousands of other patients through CUA. I don’t understand why Fauci is against it unless it’s a matter of his pocketbook or his politics.

    • I don’t think it’s an issue of bias. BarryG’s response to my comment below makes sense.

      It’d be nice if we could hear more from Fauci and less from Trump so that the actual experts could answer real questions.

  • We need every treatment available to save lives from Covid-19. This is another good one and available now. Trump supports it. Fauci doesn’t. What could be his reason? There is no good reason whatsoever not to use it.

    • In what field is your degree? Are you qualified to make this statement? “No good reason whatsoever”? This article outlines a couple of good reasons.

    • possible problems:
      1. it is costly and does nor help- always risk of other infections with injections
      2. the patient has a bad auto-immune reaction to the plasma- while the patient is trying to fight off COVID…. the problem with “throwing everything at the
      infection” is that it might burden not help the patient.

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