The eastern province of Anhui reported 231 Covid cases for Monday, with the tally since late June topping 1,000 infections. Authorities locked down Si county and one neighboring county late last week to carry out mass testing and to try and stop the virus from spreading, and pledged on Monday to stop community spread in the next three days.

Still, the virus is already spreading through the Yangtze Delta region that accounts for a quarter of China’s economy and is home to key hubs for medicine to semiconductor chips and e-commerce.

Jiangsu province, the second-biggest contributor to China’s economic output and a globally significant manufacturing hub for the solar sector, reported 66 local cases for Monday. That includes 34 in the biotech hub of Wuxi city, which has already suspended dine-in services at restaurants and closed entertainment venues. Shanghai, which neighbors Jiangsu, reported eight local cases Monday, with one infection found outside government quarantine.