Qingdao city authorities are going to test the city’s entire population of nearly 10 million people for Covid-19, they said on Monday.
The testing will be carried out in the east coast city over the next five days, CNN reports.
On Oct 11, city health authorities reported 12 new cases, six of which were asymptomatic.
All the new cases appeared to be linked to a hospital treating people who were confirmed to have the disease after returning from overseas.
Health chiefs moved fast and locked down the hospitals where they were treated as well as the buildings where they live.
More than 140,000 people who could be connected to the patients were tested and found to be negative.
Now the whole population is to be tested, in a massive military-style operation.
China has largely kept Covid-19 at bay since August, with only imported cases reported.
Tourism recently resumed in Qingdao, known for its beautiful beaches, with countless visitors arriving earlier this month for Golden Week, a national holiday around the Mid-Autumn Festival.
Now the new cases have raised concerns of a potential spike related to the holiday.