Shanghai reported 39 Covid deaths Sunday, official data showed, its highest daily toll since a weeks-long lockdown started, while China's capital Beijing warned of a "grim" situation with rising infections.
The world's second-largest economy has been struggling to stamp out its worst Covid-19 outbreak in two years with a playbook of harsh lockdowns and mass testing as it sticks to a strict zero-Covid policy, taking a heavy toll on businesses and public morale.
The cosmopolitan business hub of Shanghai has been almost entirely locked down since the start of the month, snarling supply chains, with many residents confined to their homes for even longer as it became the epicentre of the outbreak.
China's biggest city only announced its first fatalities on April 18, despite reporting thousands of cases each day in recent weeks.
It reported 39 more deaths on Sunday, National Health Commission data showed, bringing its total toll to 87, while the country logged nearly 22,000 new local virus cases.
Shanghai's previous highest daily toll since lockdown was 12, reported a day earlier.
The city of 25 million has struggled to provide fresh food to those confined at home, while patients have reported trouble accessing regular medical care as thousands of health staff were deployed for Covid testing and treatment.
Censors have battled to scrub the online backlash against the prolonged lockdown.
Meanwhile 22 new infections were reported in the capital Beijing, after warnings from an official on Saturday that the city must take urgent action.
Health official Pang Xinghuo said preliminary observations suggested Covid had been "spreading invisibly" within the capital for a week now, affecting "schools, tour groups and many families".
"The risk of continued and hidden transmission is high, and the situation is grim," Tian Wei of Beijing's Municipal Party Committee told a press briefing.
"The whole city of Beijing must act immediately."