supported by the National Key Technology R&D Programs of China(Project No.2017ZX10104001,2018ZX 10102001,2018ZX10711001,2018ZX10713002).
From July 22-23,3 local COVID-19 cases were reported in Dalian City,Liaoning Province,China.All 3 patients reported that they did not leave Dalian 14 days before the onset of disease and had no COVID-19 case contact h...