Notification on the discovery of an asymptomatic case of COVID-19 in Xiayi County On April 11, Xiayi County found an asymptomatic case of COVID-19 infection during routine nucleic acid screening for the returned centralized isolation personnel in Shanghai. The details are as follows: The asymptomatic infected person, Cao Moumou, is a returnee who helped build a shelter in Shanghai. On April 7, the report of returning home was made in advance. At 6:37 on April 10, five people and their colleag...