A medical worker collects a sample to be tested for the Covid-19. AFP
China is the last major economy wedded to a zero-Covid policy, stamping out virus flare-ups with snap shutdowns, mass testing and lengthy quarantines.
Chengdu, in the southwest, has become the latest to announce a shutdown, saying in an official notice that residents must "stay home in principle" from 6pm on Thursday to combat a new wave of infections.
Each household will be allowed to send one person out to buy groceries and essential goods per day, provided they have tested negative in the previous 24 hours, the notice said.
It said that all residents would be tested for the virus between Thursday and Sunday, and urged them not to leave the city unless "absolutely necessary".
Chinese city of Chengdu recorded 157 new local infections on Thursday.
"The current state of epidemic control is abnormal, complex and grim," the announcement said, adding that the measures aimed to "decisively arrest the spread of the outbreak and guarantee the health of all citizens".
Chengdu recorded 157 new local infections on Thursday, of which 51 displayed no symptoms, the city government said in a separate notice.
Children in at least 10 cities and provinces are facing disruption to the new academic year as pandemic controls force schools to switch to measures like online learning, according to a report on Thursday by a media outlet affiliated with the state-run People's Daily.
Xining, the capital of western Qinghai province and home to 2.5 million people, has ordered schools to conduct lessons online, rolled out a mass testing drive and told residents in its main urban area to work from home for three days.
Nurses prepare to deliver yoghurt to patients at a hospital set up for COVID-19 coronavirus patients. AFP
China has stuck fast to its zero-tolerance virus strategy despite disruptions from the fast-spreading Omicron strain and concern that the approach is stifling its post-pandemic economic recovery.
Last month, travellers in the southern island province of Hainan protested after more than 80,000 tourists were stranded in a resort city because of a Covid-19 flare-up.
Social media videos from the eastern megacity of Shanghai showed panicked crowds fleeing an Ikea store and another building as officials tried to impose local lockdowns in response to two suspected cases.