Looking through a window of her home in Suzhou's Sixian county in Anhui province, Gao Mengfan was relieved when she saw an elderly neighbor walking in his yard on Tuesday morning and knew he was not ill.

"As my mother was preparing lunch, three public health workers wearing protective gowns and face shields came to give a rapid antigen test," said Gao, who had returned to Yangji village from college on June 23 for summer vacation.

With a backyard planted with enough vegetables and a full refrigerator, Gao said her family has so far remained self-sufficient during the outbreak. "I believe dynamic clearance will be achieved soon," she said, referring to China's dynamic zero-COVID policy to control the disease.

On June 26, Sixian county reported three asymptomatic COVID-19 cases, and that was the beginning of the latest outbreak in Anhui province.

From June 26 to the afternoon of July 5, Sixian reported 218 confirmed cases and 847 asymptomatic cases, the county said in a news conference on Tuesday.

Anhui province had reported 1,081 cases by the end of Monday, most of them asymptomatic. Infections were also found in Suzhou's Lingbi county and Yongqiao district, and in Mengcheng county in Bozhou.

Thanks to the speedy response, new cases of community transmission have been steadily declining in Sixian, Suzhou authorities said on Tuesday. In the afternoon, Sixian began an eighth round of mass testing.

Jin Dongyan, a University of Hong Kong virologist, told China Newsweek that small counties with relatively low epidemic control capacity can use rapid antigen testing for epidemic surveillance. Nucleic acid testing is more demanding in terms of facilities and staff.

So far, 14,000 medical workers from other cities in the province were sent to Suzhou to assist with control of the outbreak, which also spilled out into neighboring Jiangsu province.

Sixian further strengthened control measures by introducing anti-epidemic "chiefs" at each residential community and even in each building, the local epidemic control headquarters said. Those in charge would be held accountable for cases of people who missed tests and for insufficient tracing of infections.

"Workers are seen patrolling the village, asking people who are outdoors to return home if they do not have valid reasons to be out," said Gao.

In Jiangsu province, 66 asymptomatic cases of COVID-19 were reported on Monday－34 in Wuxi, 31 in Xuzhou and one in Nanjing, local health authorities said on Tuesday.

The Shanghai Health Commission said the city had three locally transmitted confirmed cases and five asymptomatic cases on Monday. The city will conduct mass nucleic acid testing from Tuesday to Thursday in areas related to the cases.

Beijing reported seven local cases between Monday and 3 pm on Tuesday that resulted from an infection cluster involving people who had returned from overseas, the local authority said on Tuesday.

In Xi'an, Shaanxi province, citywide control measures were put in place for seven days. They include the closure of public entertainment venues and the management of facilities like nursing homes. The city of 13 million people reported 18 cases by the end of Monday.

Health authorities said on Tuesday that the Omicron subvariant BA. 5.2 is to blame for the latest cluster of cases. This is the first outbreak on the Chinese mainland caused by the subvariant, which is believed to be more contagious than earlier versions of the virus.

Zhang Haoran in Hefei contributed to this story.