More on the virus

Hydroxychloroquine did not prevent healthy people exposed to covid-19 from getting the disease caused by the coronavirus, according to a study being published Wednesday in the New England Journal of Medicine.

The study is the first randomized clinical trial that tested the antimalarial drug as a preventive measure, according to researchers at the University of Minnesota Medical School who conducted the trial. It showed that hydroxychloroquine, which has been touted by President Trump, was no more effective than a placebo — in this case, a vitamin — in protecting people exposed to covid-19.

“As we say in Tennessee, ‘that dog won’t hunt’ — it didn’t work,” said William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center. Schaffner, who was not involved in the trial, praised it as “rigorously done.”

Researchers launched the trial in mid-March. They enrolled more than 800 adults in the United States and Canada who were exposed to someone with covid-19 because of their jobs as health-care workers or first responders, or because they lived with someone with the disease. The study was a randomized, placebo-controlled trial and was double-blinded, meaning neither the participants nor the researchers knew what the participants received. Such a study is considered the gold standard for clinical trials.

Overall, about 12 percent given the drug developed covid-19, while 14 percent given the placebo also did — not a statistical difference. There was no benefit for people who also took zinc or vitamin C, the researchers said.