Rick Bright, who led the Biomedical Advanced Research and Development Authority, the agency seeding money to companies working on vaccines, said on Wednesday that he was removed from his post after he pressed for rigorous vetting of hydroxychloroquine, and that the administration had put “politics and cronyism ahead of science.”

There is no proven treatment for the coronavirus, and there is no proof that hydroxychloroquine and chloroquine can help coronavirus patients. Those two drugs are approved to treat malaria and the autoimmune diseases lupus and rheumatoid arthritis. But earlier reports from France and China suggesting a benefit led to interest in the drugs, even though the reports lacked the scientific controls needed to determine whether the drugs actually worked. The French study was later discredited.

Scientists have urged that the drugs be tested in controlled clinical trials to find out definitively whether they can fight the coronavirus or quell overreactions by the immune system that can become life-threatening. Those studies are underway in the United States and around the world.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and a member of the president’s coronavirus task force, has not endorsed the drugs, but has consistently said that scientific evidence is essential to find out whether they work.

“I have been very clear of the importance of doing randomized controlled trials to definitively prove whether something is both safe and effective,” he said in an interview.

A report on Friday, from doctors in New York, adds to concerns about combining hydroxychloroquine and azithromycin. In 84 hospitalized patients receiving the drugs, electrocardiograms found a rhythm disruption called a prolonged QTc interval a few days after the treatment began. In nine cases the disorder was severe, reaching levels known to increase the risk of sudden death. None of the patients died from heart problems, however.

Patients given the combination should be carefully monitored, especially if they have other chronic conditions and if they are also receiving other drugs known to affect heart rhythm, the doctors, from NYU Langone Health, said in a letter to the journal Nature Medicine.