Shijiazhuang, Hebei province, the worst-hit city by coronavirus this winter in the Chinese mainland, has put over 27,000 people at higher risk of infection - close contacts of confirmed cases and secondary close contacts - in 434 centralized quarantine centers citywide, said Meng Xianghong, the city's vice mayor, during a news conference on Friday night.

"All people at higher risk of infection for the disease have been put under centralized quarantine for medical observation, so as to curb further infections," she said.

For the first 12 hours on Friday, Shijiazhuang identified 48 new local confirmed COVID-19 cases and 10 asymptomatic carriers, increasing its total confirmed patients to 579 and asymptomatic results to 213, Meng said.

To screen out people carrying the virus and COVID-19 patients, the city has completed two rounds of citywide nucleic acid testing.

By 8 pm on Thursday, Shijiazhuang had finished the second round of tests for its more than 10.25 million residents. It detected 247 positive results, 217 of which were in Gaocheng district, ground zero for the province's current epidemic and also the worst-hit area in the province.

The new positive results are mainly from Zengcun town in Gaocheng and no further cluster infections in residential communities occurred, Meng said, adding all patients have been hospitalized.

To facilitate treatment for these COVID-19 patients, five of the eight medical experts who had been to hospitals in Wuhan, Hubei province during last year's COVID-19 epidemic had arrived in Shijiazhuang to give the same support.

Nangong in Xingtai, another virus-hit city in Hebei, reported 12 new confirmed cases and one asymptomatic carrier by 6 pm on Friday, making its totals 41 and 8, respectively, according to a news conference on Friday night.