Gansu province is facing a complicated and severe situation in epidemic prevention and control, a health official from the province said on Thursday.

The outbreak has the character of multiple sporadic cases, and genome sequencing showed it involved the Omicron subvariant BA.2, which is contagious and evasive and is more likely to spill over further, Wang Xuxia, a doctor with the province's center for disease prevention and control, said at a conference on Thursday.

The current outbreak, which emerged in Lanzhou on July 8, has spread and involved nine city-level and prefecture-level regions in the province as of noon on Thursday, bringing the total number of infections to 175, according to the center.

Lanzhou, the epicenter of the outbreak, registered 52 confirmed cases and 150 asymptomatic carriers, the most in the outbreak.

The virus is spreading rapidly in Lanzhou and transmission in communities has been found, Yang Dezhi, vice-mayor of Lanzhou, said at another news conference on Thursday.

"The Omicron subvariant has a shorter intergenerational transmission interval, stronger infectivity and faster transmission speed, and that is why relevant departments have imposed strict control measures for one week in the districts affected by COVID-19 to block the transmission of the coronavirus at the community level," Yang said.

The city started weeklong control measures on Monday, under which residents in the areas of high or medium risk are required to stay at home. Those in low-risk areas are being asked to go out to purchase necessities only once a day.

Public buses have been required to detour around high- and medium-risk areas while residents in the city are urged to reduce or avoid gatherings and parties.

Meanwhile, in Zhuhai, Guangdong province, authorities are still busy tracing the source of the coronavirus while introducing concrete and effective measures to curb the spread of COVID-19 in the city.

Huang Yun, deputy secretary-general of the Zhuhai city government, said epidemiological investigation and gene sequencing indicated that the COVID-19 infections detected in Zhuhai are on the same transmission chain.

"All the COVID-19 patients and asymptomatic carriers are related to the cluster outbreak involving a kindergarten in the city's Xiangzhou district," Huang said at a news conference on Wednesday night.

According to the Zhuhai city health commission, the city reported 26 new locally transmitted confirmed cases plus four asymptomatic carriers on Wednesday, bringing the city's total infections to 35.

Huang said all the 35 infections detected in Zhuhai since Monday include five kindergarten staff members, 18 children, 11 family members of the children and a close contact.

Gene sequencing indicated they were infected with the Omicron BA.5.1 subvariant.

Meanwhile, a statement released by the Zhuhai city government on Wednesday night said three women who claimed Zhuhai was going to be locked down have been detained and fined for spreading false information about the city's epidemic measures.

According to a statement released by Guangdong Provincial Health Commission, the province reported 32 confirmed COVID-19 cases, plus 11 asymptomatic carriers, on Wednesday.

In addition to 26 detected in Zhuhai, Guangzhou, Shenzhen and Foshan each reported one patient while Maoming contributed the other three confirmed cases.

The Chinese mainland on Wednesday reported 86 locally transmitted confirmed COVID-19 cases, the National Health Commission said.

Li Bin, deputy director of the National Health Commission, led a working team to Guangdong province to guide locals to contain the spread of the virus in the southern Chinese region earlier this week.

Li urged to effectively put the pandemic under control in the fastest time and with the least cost and soon achieve dynamic zero-COVID status at the community level.