After the three earlier asymptomatic patients were later designated as confirmed patients on Sunday, Qingdao immediately activated a mass epidemiological investigation and nucleic acid tests in the city. 

As of Sunday night, six confirmed COVID-19 and six asymptomatic patients were found in Qingdao, all with close connections to the Qingdao Chest Hospital. 

The Qingdao Chest Hospital is a designated medical institution for COVID-19 patients from overseas. 

Of the 377 close contacts of the three asymptomatic patients, nine tested positive for the novel coronavirus, including eight hospitalized patients and nurses, and a family member of a patient, according to the latest announcement from the Qingdao health authority. 

The Qingdao health authority said a citywide testing program has been launched. The five districts of Shinan, Shibei, Licang, Laoshan and Chengyang, home to about 6 million people, will be fully covered in the next three days. The whole city will be tested within five days, covering roughly 9 million people. 

Pictures circulated online showed local residents lining up in their communities on Sunday night waiting to get the free nucleic acid tests. Some testing points will be open from 7 am till 11 pm.

So far, all medical staff, new hospitalized patients and nurses in hospitals at Qingdao have been given nucleic acid tests, with all 114,862 results coming back negative. 

Data from the Qingdao Municipal Bureau of Culture and Tourism showed that Qingdao received 4.47 million passenger trips during the National Day and Mid-Autumn Festival holidays. 

Zhang Wenhong, China's leading infectious disease specialist and head of the Shanghai COVID-19 medical team, said Monday that since China has been relatively successful in its early fight against the epidemic, there are currently basically no local transmission cases nationwide, and Qingdao could achieve zero COVID-19 infections through expanded testing.
 
China must maintain its current anti-epidemic results, but also prepare for the gradual opening up to the rest of the world as the next step, Zhang said.