Blood plasma from recovered Covid-19 patients can help older adults avoid getting seriously sick with the coronavirus — if the therapy is administered within days of the onset of the illness, a small but rigorous clinical trial in Argentina found.
The results, published Wednesday in the New England Journal of Medicine, are some of the first to conclusively point toward the oft-discussed treatment’s beneficial effects. They arrive nearly five months after the Food and Drug Administration, under pressure from President Trump, gave the therapy an emergency green light for use in people hospitalized with Covid-19.
Thousands of patients have received infusions of plasma in the months since, while researchers waited for the data. The new study is one of the first well-designed clinical trials to show that the therapy has some benefit. “That’s kind of what we have been looking for, in terms of really having evidence,” said Dr. Boghuma Kabisen Titanji, an infectious disease physician at Emory University who was not involved in the research.
Convalescent plasma, the pale yellow liquid left over after blood is stripped of its red and white cells, teems with disease-fighting molecules called antibodies.
The new study, led by Dr. Fernando Polack, a pediatric infectious disease specialist and the scientific director of the INFANT Foundation in Argentina, appears to clarify the circumstances under which plasma performs best.
In 80 people, an infusion of plasma decreased the risk of developing a severe case of Covid by 48 percent, compared with another group of 80 who received a saline solution instead, the study found.
The study’s parameters were strict: Everyone enrolled in the trial was at least 65 years old — a group known to be at higher risk of falling seriously ill. About half of the participants also had health conditions that made them more vulnerable to the virus. And the plasma therapy, which was screened to ensure it contained high levels of antibodies, was always given within three days of the patients’ first symptoms.