Blood plasma transfusions from people who have developed antibodies to the new coronavirus appear to be safe for many COVID-19 patients, a large study suggests.

The experimental treatment — called convalescent plasma therapy — is popular because no drug has been approved specifically to treat coronavirus infection.

A week after 20,000 COVID-19 patients deemed at risk for progressing to a severe or life-threatening condition received plasma therapy, their risk of death dropped to 9%, compared to 12% in a previous study, Mayo Clinic researchers reported.

Fewer than 1% had serious side effects, the researchers added.

The study included men and women, and significant numbers of patients who were Black, Hispanic or Asian.

“We’re optimistic, but must remain objective as we assess increasing amounts of data,” principal investigator Dr. Michael Joyner, a vice chairman for research at the Mayo Clinic in Rochester, Minn., said in a clinic news release.

The researchers can’t say for sure that the transfusions from recovered patients save lives. Joyner’s team pointed out that the results might be due to patients being less ill, or to better medical care. But because the treatment is being widely used with COVID-19 patients, study continues.

Right now, convalescent plasma therapy is the only antibody treatment for COVID-19.

Plasma is the liquid part of the blood. It contains both red and white blood cells, as well as the colorless platelets the body deploys to clot and stem bleeding from wounds or cuts. And it’s also where the antibodies are, floating in the liquid.

The findings were published June 18 in the journal Mayo Clinic Proceedings.

More information

To learn more about convalescent plasma therapy for COVID-19, visit the Mayo Clinic.

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