June 3, 2020 / Associated Press
A malaria drug President Donald Trump took to try to prevent COVID-19 proved ineffective for that in the first large, high-quality study to test it in health workers and others closely exposed to people with the disease.
Results published Wednesday by the New England Journal of Medicine show that hydroxychloroquine was no better than placebo pills at preventing illness from the coronavirus. The drug did not seem to cause serious harm, though — about 40% on it had side effects, mostly mild stomach problems. 
“We were disappointed. We would have liked for this to work,” said the study leader, Dr. David Boulware, an infectious disease specialist at the University of Minnesota. “But our objective was to answer the question and to conduct a high-quality study,” because the evidence on the drug so far has been inconclusive, he said.
Hydroxychloroquine and a similar drug, chloroquine, have been the subject of much debate since Trump started promoting them in March. Hydroxychloroquine has long been used for malaria, lupus and rheumatoid arthritis, but no large studies have shown it or chloroquine to be safe or effective for much sicker patients with coronavirus, and some studies have suggested the drugs may do harm.