Most primary and secondary school students "will continue to study online at home" from Monday, municipality spokesman Xu Hejian said in a Saturday press briefing.
This announcement partly reverses an earlier decision to send young pupils back to school in stages, starting next week.
China is the last major economy still committed to a "zero Covid" strategy, which involves eradicating new cases through a combination of targeted shutdowns, mass testing and lengthy quarantines.
But the epidemic figures in recent months have put this approach to the test.
The megacity of Shanghai was forced into an exhausting confinement of several months and, in Beijing, the capital, schools were closed and the inhabitants were ordered to work from home.
Authorities in Beijing eased many restrictions earlier this week, but dozens of infections led officials to tighten some restrictions again.
Some 115 cases have been linked to an outbreak in a bar so far, said Liu Xiaofeng, municipal health official, at the press conference.
In Shanghai, a mass screening campaign affecting more than 20 million residents was launched on Saturday, less than two weeks after the end of the strict confinement imposed on the economic center in the east of the country, punctuated by food shortages and isolated protests. angry residents.
A set of restrictions have been maintained as authorities fear a resurgence of the virus after finally bringing the country's worst outbreak under control in two years.
China recorded 138 local infections on Saturday, including 61 in Beijing and 16 in Shanghai, according to the National Health Commission.
© 2022 AFP