BOSTON — Researchers at two of the state's biggest hospitals are studying the use of antibody-rich plasma from people who have recovered from COVID-19 to determine if it's effective in treating patients still fighting the virus.

But the trials underway at Brigham and Women's Hospital and Massachusetts General Hospital have been complicated, in part, by the gradually improving outlook for the coronavirus in Massachusetts, with emergency rooms in Greater Boston seeing far fewer COVID-19 patients.

Dr. Richard Kaufman, medical director of Brigham and Women's transfusion service and principal investigator for the study, said the randomized trials are promising but cautions it's too early to tell if the treatment is viable.

"It's been harder than we thought it might be," he said. "This is true not just for our own trial, but others that are underway across the world. Nobody has been able to able to finish one yet."

One issue is a lack of hospitalized COVID-19 patients.

"There's a lot of regulations, and by the time we got up and running there were very few patients," he said. "But we're still moving forward."

Another hurdle is that some patients aren’t willing to participate in a randomized study in which they only have a 50-50 chance of getting the antibody rich convalescent plasma. Patients who don't get the actual treatment get a placebo.

"We think that it’s safe and ethical to do the study this way," Kaufman said. "But some patients aren't willing to participate because of that."

Kaufman said a more definitive answer to whether plasma treatment is effective will likely require a larger pool of patients. That would only come with a second wave of COVID-19 infections.

"I’m very conflicted about that," he said. "On one hand, I hope that doesn’t happen, on the other hand, we need a lot of patients for a trial."

Recovered plasma

Plasma is the liquid portion of blood, which carries blood cells and antibodies made by the immune system to attack viruses. A recovered COVID-19 patient's plasma can be injected into a patient who's still suffering from the illness.

The practice involves drawing "convalescent plasma," or blood serum, from patients previously infected with the respiratory illness to treat others.

The plasma being used in the Brigham and Women's study has been collected by the Kraft Donor Center, a local blood bank. National blood banks, including the Red Cross of Massachusetts, have been collecting plasma from people who've recovered from the virus for several months.

Nationwide, more than 2,700 hospitals have used plasma treatment through an expanded-access program led by the Mayo Clinic. The program has provided plasma to more than 100,000 patients, according to the clinic's website.

Last month, the Food and Drug Administration granted emergency authorization allowing doctors to give the treatment earlier in the course of a COVID-19 infection, when it's believed to be most effective. The move prompted controversy within the medical community.

The search for COVID-19 treatments comes amid a global rush to develop a vaccine for the virus, which has sickened more than 6.7 million and killed more than 200,000 nationwide. Large-scale trials of vaccines developed by companies including Pfizer and Cambridge-based Moderna are underway, involving tens of thousands of people. Results are expected in the next several months.

Research is being also done on other treatments for COVID-19 and recent studies have shown promising results on the use of steroids.

Therapy with risks

FDA Commissioner Stephen Hahn was forced to publicly apologize after he was widely criticized for overstating claims that convalescent plasma treatments would save 35 lives out of every 100 people who get the therapy.

The use of convalescent plasma transfusions to treat the sick dates back more than a century, but the method has not been used widely in the United States for decades.

It was used to treat tens of thousands of patients during the Spanish flu outbreak in 1918, when modern vaccines and antiviral drugs weren't available.

The World Health Organization points out that plasma treatments, like any form of antiviral therapy, come with risks. The health agency said there have been side effects in COVID-19 patients, including lung damage.

So far, the only the only peer-reviewed study of plasma therapy for COVID-19 involved patients in Wuhan, China, the epicenter of the pandemic, and showed no significant benefits.

That study ended early because the researchers couldn't recruit enough patients.

Dr. Howard Koh, a professor at Harvard University's T.H. Chan School for Public Health, said there is no clear indication that plasma treatment works.

"We are far from having any definitive, clinical proof that it is effective and saves lives," he said. "So anyone who receives this now should fully understand that while it is authorized for emergency use it is not proven to be effective yet."

Koh, a former assistant secretary at the U.S. Department of Health and Human Services, said controlled, randomized studies like the one underway in Boston are "absolutely crucial" to understanding if the treatment can be helpful.

Christian M. Wade covers the Massachusetts Statehouse for North of Boston Media Group’s newspapers and websites. Email him at cwade@cnhi.com

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