Early into the health crisis, Gilead began testing remdesivir as a possible treatment for the illness caused by the novel coronavirus. The antiviral initially had been studied in other coronaviruses — severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). More recently, remdesivir entered clinical trials for COVID-19, and as promising data emerged, the U.S. Food and Drug Administration granted the drug Emergency Use Authorization.