Leaked contents of the cable sparked unproven speculation from senior U.S. officials beginning in April that the outbreak occurred as a result of an accident at the Wuhan Institute of Virology. The State Department has released an internal cable from 2018 detailing the concerns of U.S. Embassy officials in China about a lack of adequately trained personnel at a virology lab in Wuhan, the city that later became the epicenter of the novel coronavirus outbreak.