The city reported 29 locally transmitted COVID-19 cases, 1,580 local asymptomatic infections, 12 imported patients and five imported asymptomatic cases on Thursday, said the Shanghai Health Commission on Friday morning.Of all the local infections, 12 confirmed patients and 1,455 asymptomatic cases were detected during central quarantine, while the rest were found in the screening of high-risk people.29 local casesThe first 12 patients tested positive during central quarantine while the rest 17 tested positive in the screening of high-risk people.