SHANGHAI -- Shanghai reported four imported COVID-19 cases and no domestically transmitted cases on Wednesday, the municipal health commission said on Sept 17.

All the four cases were Chinese nationals working overseas. They arrived at the Shanghai Pudong International Airport from Equatorial Guinea, India and Singapore, respectively.

They started to show symptoms while under quarantine in Shanghai and were later diagnosed as confirmed cases. The four have been hospitalized. A total of 150 close contacts have been put under quarantine.

As of Wednesday, Shanghai had reported 612 confirmed imported cases and 342 locally transmitted cases.