Following worldwide concerns about its safety and effectiveness, the Food and Drug Administration on Monday ended its emergency-use authorization for hydroxychloroquine in treating severe COVID-19 patients. The drug has been repeatedly promoted by President Trump but large clinical trials showed that the drug was “unlikely to produce an antiviral effect,” according to the FDA’s chief scientist, Denise Hinton. The agency first provided the authorization in March for COVID-19 patients, but opted to revoke it, along with another emergency use authorization for chloroquine, following a request from the acting director of the Biomedical Advanced Research and Development Authority.