Qingdao reported a small cluster of COVID-19 infections earlier this month. Three asymptomatic patients were identified on Oct. 11, with unknown sources of infection. The city initiated nucleic acid testing for all its 11 million residents on Oct. 12. Other cities in Shandong Province also offered support to Qingdao in testing the samples. Staff at many testing sites worked extra hours or late into the night. The citywide COVID-19 screenings were completed within 5 days. The Qingdao government said results showed no new positive cases. In the meantime, experts were dispatched to trace the source of the new infections. Within 5 days, the source has been traced to two dock workers who underwent CT scans at a hospital. Due to improper disinfection, the CT room was contaminated and the virus further infected other people. From Oct. 11 to 15, the coastal city reported a cluster of 13 confirmed coronavirus cases. Also within 5 days after the new infections emerged, Qingdao ruled out the risk of further community transmission.