China is starting mass testing on 3 million people in a section of the northern city of Tianjin and has tested 4,015 others in a hospital in Shanghai after the discovery of a pair of cases there. The National Health Commission recorded seven new domestically transmitted cases Saturday, including five in Tianjin and two in Shanghai. Tianjin on Friday reported community transmission involving four different individuals and another case. In response, local authorities sealed off the residential community where the people lived as well as a hospital and a kindergarten. On Saturday, authorities have starting testing all residents in the Binhai district of Tianjin. Authorities in Shanghai sealed off a hospital after a husband and wife tested positive for COVID-19.