QINGDAO, Nov. 12 (Xinhua) -- The eastern Chinese city of Qingdao has seen the number of confirmed COVID-19 cases drop to zero, the local health commission said Thursday.

As of Wednesday, all 14 patients reported since Oct. 12 were discharged from the hospital after recovery, according to the Qingdao municipal health commission.

Earlier investigation showed inappropriate disinfection in the CT room at the Qingdao Chest Hospital led to the new cluster of infections after two stevedores, who had handled imported frozen seafood, were diagnosed as asymptomatic COVID-19 cases on Sept. 24. They were isolated at the Qingdao Chest Hospital and underwent CT scans in the hospital's CT room.

Qingdao conducted a citywide nucleic acid testing campaign covering all 11 million residents within five days to contain the spread of the virus.