WESTERLY, R.I. (WPRI) — Two COVID-19 patients receiving an experimental plasma treatment at Westerly Hospital have been taken off ventilators, but doctors are remaining cautious about the treatment’s success.

Westerly is among the Yale New Haven Health hospitals participating in the Mayo Clinic’s convalescent plasma study, which uses plasma from from recovered COVID-19 patients to treat those with active infections. The idea is that the antibodies in the recovered patients’ blood will help people currently battling the disease.

Asked about the progress of the treatment during a Zoom press conference on Wednesday, Dr. Tom Balcezak, Yale New Haven Health’s chief clinical officer, said it’s yet not clear how big of a role, if any, the plasma is playing in patients’ recoveries.

“The patients are doing extremely well,” Balcezak said. “The challenge here is again — and I sound a little bit like a broken record — we don’t know if the convalescent plasma is adding to that, or whether or not [it’s] just good, supportive care.”

Balcezak said the nationwide study will help determine whether convalescent plasma is an effective treatment for COVID-19. 

“We don’t know that convalescent plasma works. We’d like to think that it does,” he said. “The code has not yet been broken.”

Currently, three COVID-19 patients at Westerly Hospital are receiving the experimental treatment, which has previously been used to treat viruses like SARS and Ebola.