A medical worker checks a driver's temperature, amid the novel coronavirus outbreak, in Harbin, Northeast China’s Heilongjiang province, Feb 1, 2020. (Photo: Xinhua)

All residential communities and villages in Wangkui county of Suihua city, Heilongjiang province, have been placed under lockdown management, a local official said on Monday afternoon.

Schools and other educational institutions have been temporarily closed, and entertainment facilities and private clinics have also suspended service as well, according to the county government.

Residents are required to submit a negative nucleic acid test result, conducted within three days before leaving the county.

Huiqi village in the county has been classified as a medium-risk area for COVID-19 starting on Monday.

As of 10 am on Monday, the county had a total of 20 local asymptomatic carriers of COVID-19, said Li Yuefeng, secretary-general of Suihua city, at a news conference held on Monday afternoon.

After the emergence of the first case, a 31-year-old female resident who tested positive for coronavirus on Saturday when she sought medical treatment at the Wangkui People's Hospital outpatient clinic, Suihua immediately implemented an epidemic prevention and control response and has traced more than 500 close contacts.

The city has collected 8,791 nucleic acid test samples of relevant people and received 2,848 results, 20 of which came back positive.

All 20 patients were diagnosed as asymptomatic cases after expert consultation and have been transported to a designated hospital in Suihua for medical observation and treatment.

Wangkui has conducted large-scale coronavirus tests covering all residents and it is expected to finish all work within three days, Li said.