Researchers ask if survivor plasma could prevent coronavirus

Survivors of COVID-19 are donating their blood plasma in droves in hopes it helps other patients recover from the coronavirus. Thousands of coronavirus patients in hospitals around the world have been treated with so-called convalescent plasma — including more than 20,000 in the U.S. — with little solid evidence so far that it makes a difference. “We have glimmers of hope,” said Dr. Shmuel Shoham of Johns Hopkins University.