The Food and Drug Administration on Thursday approved Gilead Sciences’ antiviral drug remdesivir as a treatment for the coronavirus. In May, the FDA granted the drug an emergency use authorization, allowing hospitals and doctors to use the drug on patients hospitalized with the disease even though the drug has not been formally approved by the agency. The intravenous drug has helped shorten the recovery time of some hospitalized Covid-19 patients. It was one of the drugs used to treat President Donald Trump, who tested positive for the virus earlier this month.