Pressure is mounting on officials to avert a wider spread and disruptions similar to the painful and costly isolation that Shanghai, China's most populous city, suffered in April and May.
"Several Chinese areas are facing local outbreaks and infections have emerged at the community level in Shanghai, to which we should attach great importance," city health official Zhao Dandan told reporters on Wednesday.
"There should be no slacking," Zhao said.
While the country's latest daily caseload of just over 300 infections is insignificant by global standards, worries it could trigger another round of strict curbs weighed on Chinese stocks and markets worldwide.
China is the only major economy digging in its heels on a "zero-COVID" policy aimed at promptly eradicating all outbreaks, while the rest of the world tries to co-exist with the virus.
Shanghai, which reported 24 new cases for Tuesday versus eight the previous day, is testing all residents in nine of its 16 districts from Tuesday to Thursday as well as those in parts of three other districts.
The commercial hub of around 25 million already requires residents to get tested frequently in order to enter shopping malls or take public transport.
City authorities have suspended operations of karaoke lounges, but other recently-reopened cultural venues such as libraries will stay open. Cinemas are due to reopen on Friday.
Beijing, which reported six cases on Tuesday, urged transport hubs and hotels to check the body temperature of visitors and proof of negative COVID test results.
The caseload in the eastern Anhui province, where more than 1 million people in small towns are under lockdown, declined slightly to 222 on Tuesday from 231 a day before. The province still accounts for most of China's new infections.
In the northwestern city of Xian in the Shaanxi province, a seven-day closure of various entertainment venues and suspension of dining-in at restaurants went into effect on Wednesday. The city of 13 million detected 11 new cases on Tuesday.
Xian, famed for its Terracota Army, is the first major Chinese city to declare a fight against the BA.5.2 subvariant of the contagious Omicron COVID variant, seen as more infectious than the BA.2 subvariant found in earlier outbreaks in China.
Shaanxi governor Zhao Yide said the province's cities should enter a "war-time" state and ramp up screening of travellers.
In the eastern Jiangsu province, 65 new cases were detected on Tuesday. The Chinese Athletics Association has cancelled the November 2022 World Athletics Half-Marathon Championship that was scheduled to be held in the province, in Yangzhou.
President Xi Jinping said it was better to incur "temporary" economic costs than to "harm the lives and health of the people" and that accepting COVID as endemic would have "unimaginable" consequences in China.
Officials have pointed to the millions of COVID-linked deaths around the world, versus the 5226 reported in China.
