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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A study released Aug. 13 — but not yet peer-reviewed — suggested that using convalescent plasma to treat patients with severe Covid-19 soon after their diagnosis was associated with a lower likelihood of death.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.”

  • Our country needs the information that can be obtained by the simple expansion of testing all blood donations in the US for antibodies while testing the test against each other. 13.2 million blood donors and 17.2 million units of blood. Each donor is tested using a different test for each donation. If one test out of a number of them test different than the others then it is evidence of a person’s antibodies and immunity ending or that the test is unreliable or inaccurate. A person can donate platelets 24 times a year. They can donate each week for 24 weeks in a row. Plausma every 29 days and whole blood every 56 days. Testing for anti bodies will provide scientific evidence of antibody immunity and how long it last while at the same time working to develope facts on how and for how long the T and B memory immunity cells last. We will be able to encourage more people to donate blood and to create a profile of people who are likely to be asymptomatic or to have a mild response to being infected. Once identified we can track them and/or have them donate platelets each week. We can begin to determine how their immune system only had the lower level infection. We will be able to determine how long each person’s contagious period lasted and to slow down or stop silent spreading. We can also be able to begin to understand how we can use low doses of the virus as a vaccine. As it is right now we do not know how many of our donors have already been infected and if they might be able to donate plausma. The Red Cross and Life South are testing all their donors. America’s Blood Center is in the process of attempting to end the requirement of testing for the Zeka virus. They report that it cost 137 million dollars to test for it. That money could be directed to in part pay for the antibody testing. We need also to establish a priority study on the T and B cell immunity. When we can accurately report how the T and B cells work and last then we can establilsh a controlled herd immunity program. Actually the Asymptomatic and mild infections are creating an uncontrolled herd immunity. The problem with this is that uncontrolled infections can result in a moderate to severe response. If the uncontrolled infection result in a later reported infection they may be in a severe stage that little can be done for the.By controlling the viral loading the most vunerable can continue to self isolate and protect themselves and the least vuneralble can volunteer to be vaccinated with the virus. We can medically prep them for innoculation, monitor them for any unexpected response and provide early treatment should they need it. WE sould no longer have to wonder whether an vaccinated person has been infected, are they asymptomatic, should they be tested. After the innoculation we can test them as often as needed tor further information to help end this viral attack on our society and economy.

    • all great ideas, none of that will happen as long as we have a POTUS who ‘takes no responsibility” except for denying there is a serious pandemic. People do get reinfected (my kid had two positive tests end a April -> asymptomatic and positive again beginning of August -> with moderate symptoms, v v fit healthy 20 yo. We are in this for the long hall. Real Science can SAVE us.

  • Thank you to all who contributed to this topic. I am not a Scientist or Medical Expert. None the less, the comments helped me weed through all the information and more importantly disinformation that is out there on the internet. The Real purpose of this comment is just my desperate attempt to stop e-mail notifications. LOL

  • Abstract:
    We document four facts about the COVID-19 pandemic worldwide relevant for those studying the impact of non-pharmaceutical interventions (NPIs) on COVID-19 transmission. First: across all countries and U.S. states that we study, the growth rates of daily deaths from COVID-19 fell from a wide range of initially high levels to levels close to zero within 20-30 days after each region experienced 25 cumulative deaths. Second: after this initial period, growth rates of daily deaths have hovered around zero or below everywhere in the world. Third: the cross section standard deviation of growth rates of daily deaths across locations fell very rapidly in the first 10 days of the epidemic and has remained at a relatively low level since then. Fourth: when interpreted through a range of epidemiological models, these first three facts about the growth rate of COVID deaths imply that both the effective reproduction numbers and transmission rates of COVID-19 fell from widely dispersed initial levels and the effective reproduction number has hovered around one after the first 30 days of the epidemic virtually everywhere in the world. We argue that failing to account for these four stylized facts may result in overstating the importance of policy mandated NPIs for shaping the progression of this deadly pandemic

    Sent from my iPad

    • If its bodily fluids, than here the people in the desert golfing in 110 degrees there sweat hitting others, and the tee off will have all of these fluids on these tees…. yet they were able to stay open. So if someone has lil scratches on there arm, and reaching for that produce, that had sweat, tears, and if they have a mask on they sneeze their will be lots of spit and snot on these items.
      The sanitizers are SUFFOCATING, especially for asthmatics, and compromised lungs.
      Those masks can cause more lung issues.
      NO ONE WHERES MASKS in this heat period, it’s an instant death.
      The virus had too many different strains, and people built an immune system to this virus.
      We lost more women to heart and breast cancer, pneumonia.
      China had the largest outbreak, the recipients IN CHINA ALL WEAR MASKS FOR THE LAST 30 YRS!!!? CAUSE OF THE POLLUTION….
      Gloves started for anyone handling food cz of AIDS, just in case they cut themselves.
      I only wear a mask when mandated.
      I dont know why people believe the COVID19 slow down was due to masks!!!? Or lockdown.
      It did not.
      It’s a virus, and autopsies were not performed, and NYC was used to gain control.
      If you can tell me why was the public told the virus life on certian surfaces was up to 76 hrs….lol not 72 76? It was airborne up to 27 hrs…
      Why dont you work on the obvious, the cure.
      Why is it that it’s not spread through blood? Or is it.
      I believe theres a virus. It’s not no where as debilitating as HEPC B E
      so I’d rather go fast than by cancer of any organ.

  • For those that insist that masks don’t work, why aren’t people tending to infected patients getting sick in large numbers? Protective gear works, that is why. What do masks do that causes them to work. They slow down the speed breath exits and that reduces the area contaminated by the simple act of breathing or talking. The mask doesn’t keep you from getting sick as much as it prevents others from getting sick because of the much smaller area of air contamination around the infected person. That is why masks are so important. They don’t block the germs, they just restrict the area of contamination and the number of people exposed. Social distancing works in an identical manner. The 6 feet is defensive, in case the other person is not wearing a mask. If everybody was wearing a mask the social distancing would only need to be 2-3 feet. To say masks don’t work is the denial of science. Yes, some designs work better than others because some, such as cloth, are better at restricting the rate of air movement. It is like the ripple effect of dropping a pebble in still water. A mask works like a smaller pebble. It has a smaller ripple effect. It is an example of low tech that is effective.

    • Well said.

      Masks are like condoms. They’re not 100% effective, but they greatly improve your chances. And used in conjunction with other methods, they get you pretty close to certainty.

    • You can vote in person.

      There’s a push to have more people vote by mail so the crowds will be smaller — another preventative measure that, in combination with masks and social distancing, will make us all safer.

      If you’re concerned that your vote won’t be counted if you vote by mail, use a dropbox or even hand your ballot to an election official, then go to the polls in person. You might have a longer wait than usual because of sanitizing considerations, or, if a lot of people vote by mail or dropbox, you might not.

  • That’s not true. The Mayo Clinic study found that mortality dropped by 36.8% when comparing those treated within 3 days to those treated 4 days or later than the diagnosis. Those results are significant. Math numbers are not a matter of opinion.

    What is not proven is whether providing blood plasma for severe patients is better than not treating those patients. Although we know that early treatment is better than later treatment, we don’t yet know that treatment is better than no treatment.

    I would trust the Mayo Clinic before I would trust Fauci. The Mayo Clinic is the best hospital in the country, and Fauci is a political hack. I would rather allow doctors to treat patients with plasma rather than see those patients untreated.

  • This article is now moot because Dr. Hahn has said he misspoke. He now says that while the treatment is safe the effectiveness is so far unproven against Coronavirus. Hahn: “What I should have said better is that the data show a relative risk reduction not an absolute risk reduction.” It is what it is.

  • Es interesante el tema y en China se comprobó que un paciente volvió a dar positivo pero se mantuvo asintomático en el segundo proceso. Eso da pie a que se crea en el factor inmunológico que el organismo crea al superar una primera infección. Deberían profundiza más en el tema y hacer seguimiento a su desarrollo. Excelente reportaje.

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