QINGDAO - Inadequate disinfection of a CT room at Qingdao Chest Hospital led to the new cluster of COVID-19 infections in Qingdao, east China's Shandong province, a local health official said Friday.

Inadequate disinfection of a CT room at Qingdao Chest Hospital after two infected persons went inside led to the new cluster of COVID-19 infections, Ma Lixin, deputy Party chief of the provincial health commission, said

Two stevedores who had handled imported frozen seafood at the port of Qingdao were diagnosed as asymptomatic COVID-19 cases on Sept 24. They were isolated at hospital and underwent CT scans in the hospital's CT room.

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Due to inadequate disinfection, the CT room was contaminated and the virus further infected other people, Ma Lixin, deputy Party chief of the provincial health commission, said at a press conference.

Ma noted that the new cluster of infections was neither caused by nor has caused cross-infection in the community.

A total of 13 confirmed cases of COVID-19 had been reported in this new wave of infections by Thursday.

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Qingdao has completed a citywide nucleic acid testing covering all its 11 million residents. The city had vowed to complete the mass testing campaign within five days starting from Monday.

As of 8 am Friday, more than 10.16 million of the collected samples had been tested, and results showed no new positive cases, Xue Qingguo, Qingdao's deputy mayor said, adding that the results of the remaining samples will be released later in the evening.