UNM finds limitations with plasma treatment

Antibody levels vary; dose, when to administer among questions

University of New Mexico researchers stopped a clinical trial earlier this month after finding no benefit to treating COVID-19 patients with convalescent plasma from people who survived the disease.

Those researchers were surprised last week when President Donald Trump announced that the Food and Drug Administration had given emergency approval to expand the use of that therapy, describing it as a “very powerful treatment.”

“We were surprised by the FDA coming out with the (emergency use authorization),” said Dr. Michelle Harkins, the division chief of Pulmonary, Critical Care and Sleep Medicine at UNM. “There’s so many questions we don’t know.”

Plasma has already been used across the country on tens of thousands of patients with COVID-19, including some in New Mexico, Harkins said. As many as 70,000 people have already received plasma in some capacity, according to the Associated Press.

The university medical center has taken a limited approach with the therapy, Harkins said.

As part of a research study published this month in the Journal of Infectious Diseases, 12 COVID-19 patients hospitalized at UNMH received plasma as part of a clinical trial. After receiving the transfusion, the patients were monitored for 14 days to measure coronavirus antibodies in their blood.

After the monitoring period, the UNM researchers — there were 11 UNM employees listed as authors to the journal article — found no evidence the plasma treatment produced an immune response. So the study was brought to a halt.

Harkins said the school is planning to participate in two additional clinical trials using plasma therapy. And she said there was no evidence the treatment hurt their patients.

A plasma therapy treatment includes taking blood plasma from people who previously recovered from COVID-19 and then transfusing that plasma into a patient battling the disease. The idea is that antibodies created by the former patient will help the current one.

The practice has been used for a century to ward off other diseases like measles and the flu.

Earlier this month, the Mayo Clinic, which has developed a protocol for administering plasma to COVID-19 patients across the country, said preliminary data suggests the treatment may help COVID-19 patients recover, according to the Associated Press.

But Harkins said that the initial study at UNM led to more questions than answers. It’s not clear who is the best candidate for

the treatment, how big of a dose they should receive and when they should receive the plasma.

And there were problems with the plasma itself. She said that the plasma samples the hospitals received had widely different concentrations of antibodies.

Several things could contribute to that, Harkins said. Perhaps people with a more severe case of COVID-19 create more antibodies than those who report mild systems, and it’s not known how long those antibodies will stay in the body, she said.

The UNM researchers concluded that pre-screening convalescent plasma donations to find those with high antibody levels may be necessary.

“We were initially very excited about convalescent plasma because of its use in helping treat other viral infections,” Harkins said. “I want to be able to use it if I think it will help my patient, rather than randomly administering it.”