Work on hydroxychloroquine delayed promising studies of convalescent plasma

Robust scientific studies on convalescent plasma, a potentially promising COVID-19 treatment, have gotten off to a slow start in the U.S., in part because some researchers were more focused on enrolling their sickest patients in other trials, including some for hydroxychloroquine.

"You always have that hindsight and say, oh man, we should have put our efforts into something else," said Dr. Todd Rice, an associate professor of medicine at Vanderbilt University Medical Center.

Early on in the pandemic, Vanderbilt was involved in multiple clinical trials, including those on remdesivir and hydroxychloroquine. Even though the hospital system had also developed a randomized, placebo-controlled trial for convalescent plasma, Rice said, the other trials took priority.

While remdesivir was found to be beneficial to patients with COVID-19, the disease caused by the coronavirus, a number of large clinical trials on hydroxychloroquine ultimately failed to show any benefit.

Convalescent plasma comes from patients who have recovered from the coronavirus. Plasma is the part of blood that's left over when red and white blood cells are removed, leaving behind a yellowish, watery substance rich in proteins and antibodies. It's those antibodies that help the immune system fight off viruses. The idea is that giving a sick person an infusion of COVID-19 antibodies would give the patient's immune system a much-needed boost in fighting off the virus.

In the past week, the Trump administration has stepped up its call for people who have recovered from the illness to donate plasma. It has also pumped millions of dollars into an expanded access program run by the Mayo Clinic, which helps doctors quickly get their patients plasma infusions. At least 53,000 COVID-19 patients across the U.S. have participated.

But because everyone gets the real plasma in the program, there's no way to evaluate how well the infusion actually works. That would be done by comparing the treatment to a placebo, or control, group.