China has stepped up efforts to contain a new cluster of COVID-19 infections, with 328 new locally transmitted confirmed cases registered in July.

　　The outbreak stems mainly from a flight that departed from Russia and landed in Nanjing, capital of east China's Jiangsu Province.

　　Viral genome sequencing has found that all strains in the recent resurgence were the highly infectious Delta variant, which can contribute to a faster and wider transmission among a large population, according to He Qinghua, an official with China's National Health Commission.

　　Currently, the variant has spread to more than 10 provinces, including central China's Henan and Hunan.

　　Nanjing has manifested a downward trend in its newly confirmed cases with tightened prevention and control measures in place.

　　The city has launched three rounds of all-inclusive nucleic acid testing and kick-started its fourth mass testing campaign on Monday, covering nine districts, said Yang Dasuo, deputy director of the municipal health commission.

　　Jiangsu has canceled all flights at Lukou International Airport since July 30. Anyone leaving Nanjing must present a negative nucleic acid test certificate issued within 48 hours before their departure.

　　The province has also provided relevant information of travelers who had visited Nanjing since July 6 to their destination provinces and cities.

　　In the Tangshan branch of the Second Hospital of Nanjing, the city's designated hospital for COVID-19 treatment, over 1,000 beds are ready.

　　Meanwhile, Nanjing has launched closed-off management in all its nursing institutions for the elderly, beginning July 20.

　　The city of Zhangjiajie, a renowned tourist destination in Hunan, closed all its tourist sites starting Friday.

　　All visitors are asked to take three nucleic acid tests and receive negative results for COVID-19 before they leave the city.

　　China's top epidemiologist Zhong Nanshan said recently that preliminary studies on Guangzhou's latest COVID-19 outbreak show that China's domestic vaccines are proving effective in protecting its people against the Delta variant. The protective effect of China's domestic vaccines is 100 percent effective against severe cases, 76.9 percent against moderate cases, 67.2 percent against mild ones, and 63.2 percent against asymptomatic carriers.

　　Produced by Xinhua Global Service