Around a dozen new infections were detected over the weekend in the eastern coastal city. Most of the new infections were linked to a hospital.
More than 140,000 people, mainly working in the health sector, were tested immediately after the first positive cases emerged.
Recently China has only recorded coronavirus infections imported from abroad.
The country brought the virus’ spread under control with tough measures such as locking down cities where millions live, strict isolation and entry bans.
There have been several limited localized outbreaks, as in Qingdao now, but they have been swiftly halted. Mass testing was also used in those cases.