This week, President Trump announced the Food and Drug Administration is making it easier for COVID-19 patients to get convalescent plasma, a potential treatment made from the blood of people who’ve recovered from a COVID-19 infection.
Scientists don’t know if the treatment works yet, but a team at Oregon Health & Science University is part of a new nationwide clinical trial trying to answer that question.
The idea behind convalescent plasma is that it may confer what’s known as passive immunity to the recipient. Plasma is the part of blood that contains antibodies.
“You take antibodies from someone who has recovered, and you give them to someone who is sick, in the hopes of getting them better, faster,” said Dr. Mohamud Daya, a professor of emergency medicine at OHSU. “It’s a very old form of immunotherapy.”
Antibodies collected from blood plasma are used to treat people infected with the rabies and tetanus viruses, for example.
The FDA’s emergency use authorization for convalescent plasma allows the largely untested treatment to be used for the sickest COVID-19 patients: people who have been hospitalized.
The clinical trial OHSU is part of will target a different group in its effort to collect evidence for whether the treatment is effective: people who show up at emergency rooms with mild COVID-19 symptoms, but are at risk for developing more serious illness.
The study is a randomized controlled trial — the gold standard in scientific research for establishing whether a treatment works. OHSU is participating as part of a consortium of emergency departments across the country that collaborate on research.
To be eligible for the trial, patients need to be in their first week of illness, well enough to return home without needing oxygen support, and have at least one risk factor for developing more serious infection, like being older than 50 or having diabetes or hypertension.
Half of the patients who enroll in the study will receive one unit of antibodies, while the other half will receive a placebo — vitamins and saline solution. Researchers will track both groups to see if those who get antibodies do better.
Nationwide, researchers hope to recruit 600 people to participate in the trial over the next three months.
Daya said doing a randomized controlled trial is critical. The research to date — including a preliminary paper from Mayo Clinic researchers that the FDA cited in its decision to make the treatment more widely available — has established that convalescent plasma is safe for COVID patients, but hasn’t proven its efficacy.
Daya said while the Mayo Clinic paper reported somewhat better outcomes for patients who got the antibody treatment earlier in their illness, the data is muddied by the variety of other treatments the patients were receiving, like antiviral drugs or being placed on their stomachs to help with breathing.
“If I’m giving you 16 things, including convalescent plasma, and you get better, is it the convalescent plasma that made you better, or is it one of the other therapies? That’s been the hardest part of the data,” he said.
Some scientists have raised concerns that by expanding patient access to antibody treatment, and hyping a therapy that may not work, the FDA is making it harder for researchers to recruit people to participate in clinical trials on convalescent plasma. The fear is patients will demand the treatment and not want to risk getting a placebo.
Daya said because the clinical trial of which OHSU is part focuses on outpatients who aren’t likely to qualify for convalescent plasma under the Emergency Use Authorization, he does not think the trial will be undermined by the EUA. But he is concerned about the potential for shortages of plasma if people begin to believe the treatment works before the evidence truly exists.
“Hopefully, the blood banks and the Red Cross and others have convalescent plasma available. Supply is often the issue,” he said.
Daya said researchers need time to understands lots of questions — not only whether the therapy works, but what’s the right dose and which patients will benefit the most.
