Multiple Chinese cities are adopting fresh Covid-19 curbs, from business halts to lockdowns, to rein in new infections, with the commercial hub of Shanghai bracing for another mass testing effort after finding a highly-transmissible Omicron subvariant. The tough curbs by local governments follow China’s “dynamic zero-Covid” policy of promptly stamping out all outbreaks at a time when much of the world co-exists with the virus.

China has said curbs must be as targeted as possible to reduce damage to the world’s No. 2 economy, after this year’s major disruptions clogged global supply chains and hit international trade. The discovery of a local infection with the BA.5.2.1 subvariant raises the stakes of quickly limiting a small outbreak to avert more disruptive steps similar to the lockdown in April and May that roiled the global economy and markets.

The BA.5 lineage, spreading fast in many other countries, has been detected in cities such as Xian in the province of Shaanxi and Dalian in Liaoning province, hundreds of kilometres on either side of Beijing. It was first found in China on May 13 in a patient who had flown to Shanghai from Uganda, the China Center for Disease Prevention and Control said, with no local infections linked to the case that month.