The city reported 311 locally transmitted COVID-19 cases, 16,766 local asymptomatic infections, four imported patients and one imported asymptomatic infection on Tuesday, said the Shanghai Health Commission on Wednesday morning.Of all the local infections, 40 confirmed patients were previously asymptomatic infections. Four confirmed patients and 16,256 asymptomatic cases were detected during central quarantine, while the rest were found in the screening of high-risk people.311 local casesThe first four patients tested positive during central quarantine.