Convalescent Plasma Found Safe as Covid-19 Therapy

Blood plasma donation (ANKAWÜ, Wikimedia Commons)

19 June 2020. Donated blood plasma from people who recovered from Covid-19 infections is found to cause few serious side effects when given as a treatment for infections in others. Researchers from Mayo Clinic in Rochester, Minnesota and other clinic sites, with colleagues at other institutions, reported their findings yesterday in the journal Mayo Clinic Proceedings.

Plasma is the liquid part of blood that contains antibodies produced by the immune system. The plasma from individuals who recovered from Covid-19 infections is believed to contain antibodies that can prevent or treat infections in other people. As a result, a nationwide campaign is underway to encourage individuals who recovered from Covid-19 infections to donate their convalescent plasma, as it’s called. The U.S. Food and Drug Administration in April provided guidance for researching convalescent plasma as a Covid-19 treatment, updated in May, and encourages donations on the agency’s web site.

An early and continuing concern of convalescent plasma is its safety, particularly when given to the sickest Covid-19 infection patients. Michael Joyner, who studies interactions between the nervous system and heart functions in reaction to stress at the Mayo Clinic, is leading the Expanded Access research program for plasma donations, and is the lead author of the Mayo Clinic Proceedings paper.

The paper reports on donated plasma transfusions given to some 20,000 Covid-19 patients between 3 April to 11 June, 2020. Joyner and colleagues. earlier reported on the first 5,000 patients receiving plasma transfusions, and the new paper adds data from another 15,000 plasma recipients. Some 680 or about three percent of recipients experienced serious cardiac reactions after the transfusions, and 87, or less than one percent, experienced blood clots deemed serious events. Another 89 patients, less than one percent, also reported serious transfusion reactions.

However, the vast majority of the cardiac events, 562 of 680, and blood clots, 55 of 87, were considered unrelated to the plasma transfusions. Some of the cardiac problems were experienced by patients also receiving hydroxychloroquine, for which FDA since revoked its emergency authorization as a Covid-19 treatment due to cardiac risks. The mortality rate among Covid-19 patients within seven days receiving plasma transfusions was 8.6 percent, compared to 12 percent reported among the first 5,000 patients. In addition higher rates were experienced among the sickest recipients: those in intensive care (10.5%), mechanically ventilated (12.1%), and with septic shock or multiple organ failure (14.0%).

The results show as well that convalescent plasma recipients are a diverse group in terms of gender and ethnicity. Nearly 40 percent of patients were women, with 20 percent African-American, 35 percent of Hispanic origin, and five percent Asian-American. In addition, participants included incarcerated individuals, a group considered at particularly high risk of Covid-19 infections. The authors note that most of the patients were overweight or obese.

The authors also point out that the relatively low rates of serious adverse effects show convalescent plasma is safe as a Covid-19 treatment, and the lower seven-day mortality rate among the larger group — 8.6 percent for all 20,000 participants, compared to 12 percent for the first 5,000 — is an indicator of efficacy, but not conclusive at this point. “Our efforts to understand convalescent plasma continue,” says Joyner in a Mayo Clinic statement. “We’re optimistic but must remain objective as we assess increasing amounts of data.”

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