UM study casts doubt on convalescent plasma treatment for COVID-19

COVID-19 illness progressed just as quickly in high-risk patients who received convalescent plasma in emergency rooms as it did in those given a placebo, University of Michigan researchers concluded in a study published Wednesday in the New England Journal of Medicine. 

The plasma donated by people previously infected with COVID-19 contains antibodies that researchers hoped would fight the virus in people newly infected with the SARS-CoV-2 virus. 

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Michigan Medicine researchers helped design the trial for using convalescent plasma to treat ER patients. Nationwide, 48 hospitals participated including Spectrum Health hospitals in West Michigan, and Detroit Receiving and Beaumont hospitals in Metro Detroit. 

Dr. Frederick Korley, lead author of the study and an associate professor of emergency medicine at the University of Michigan Health System, said the trial was the only way to know if convalescent plasma had an effect. The study was funded by the National Institutes of Health.

"Our study examined patients with mild COVID-19 illness, and we randomized them to receive either convalescent plasma or a placebo," Korley said. "We wanted to see if the convalescent plasma could prevent disease progression to a more serious illness.

"We were treating people early in their disease before they got so sick they needed oxygen supplementation."

Of 511 patients, 257 were enrolled in the convalescent plasma group and 254 in the placebo group between August 2020 and February of 2021, according to the NEJM report.

All the patients came to the emergency department within 7 days of symptom onset and were in stable enough condition for outpatient management. The patients were either 50 or older or had one or more risk factors for disease progression. 

Fifteen days after receiving either the treatment or the placebo, researchers found that COVID-19 illness progressed in 77 patients who received the plasma, about 30%, compared with 81 of the patients in the placebo group, about 31.9%. 

"Our study doesn't necessarily mean that convalescent plasma doesn't work at all, it just didn't work in this setting," Korley noted. "We gave it to them within seven days of illness.

"We still don't know if we treated them a lot earlier whether that would have made a difference. We also don't know if we had given them a higher dose of convalescent plasma, whether that would have made a difference. There are still some unknowns."

Korley said most hospitals have already stopped administering convalescent plasma as a treatment for COVID-19. The federal Food and Drug Administration initially granted emergency authorization for its use in treating COVID-19 patients sick enough to be admitted to the hospital.  But the FDA withdrew its permission after earlier studies found the treatment was ineffective for treating hospitalized patients.

Convalescent plasma, Korley noted, differs from monoclonal antibody treatment, which is still being used in hospitals and the subject of clinical trials.

Korley said convalescent plasma contains multiple kinds of antibodies produced by the body. Monoclonal antibodies are produced in a lab, and are identical to each other. But they are present in much higher concentrations in monoclonal antibody treatment than the antibodies contained in convalescent plasma. 

"I do feel a little bad," Korley said about results of Michigan Medicine's convalescent plasma study, "because the great thing about the study was people (who donated plasma) felt like they were helping people — I think there's still something very noble about that.

"I think this is an important lesson for all of us that not everything that sounds good, that seems right, is right. And we always have to study it." 

kbouffard@detroitnews.com

Twitter: @kbouffardDN