SHANGHAI (NYTIMES) - Parents have organised petitions, imploring the government not to separate children infected with the coronavirus from their families.

Patients have demanded to speak with higher-ups about shoddy conditions at isolation facilities. Residents have confronted officials over containment policies that they see as unfair or inhumane, then shared recordings of those arguments online.

As the coronavirus races through Shanghai, in the city's worst outbreak since the pandemic began, the authorities have deployed their usual hard-nosed playbook to try to stamp out transmission, no matter the cost.

What has been different is the response: an outpouring of public dissatisfaction rarely seen in China since the chaotic early days of the pandemic, in Wuhan.

The crisis in Shanghai is shaping up to be more than just a public health challenge. It is also a political test of the zero tolerance approach at large, on which the Communist Party has staked its legitimacy.

For much of the past two years, the Chinese government has stifled most domestic criticism of its zero tolerance Covid-19 strategy, through a mixture of censorship, arrests and success at keeping caseloads low. But in Shanghai, which has recorded more than 70,000 cases since March 1, that is proving more difficult.

Shanghai is China's most populous metropolis, its shimmering commercial heart. It is home to a vibrant middle class and many of China's business, cultural and academic elite. A large share of foreign-educated Chinese live in Shanghai, and residents' per capita disposable income is the highest in the country.

Even in a country where dissent is dangerous, many there have long found ways to demand government responsiveness and have a say over their own lives.

"I'm just too angry, too sad," said Ms Kristine Wu, 28, an employee of a tech company who was visited at home by two police officers after she criticised the city's Communist Party leader on social media.

She recorded her defiant confrontation with them, in which she asked why they were wasting time harassing her, when they could be helping people in need of care.

She then shared a photo of the encounter on social media, despite the officers' warnings against doing so. It was later censored.

"I thought, whatever, I'll just go for it," said Ms Wu, who had not considered herself political before the lockdown. "I used to live pretty comfortably, and before anything had happened, everyone was very polite, very rule abiding. Now all that has just crumbled."

For now, the government looks largely unmoved. A Chinese vice-premier visited Shanghai and demanded that officials focus on eliminating cases "without hesitation".

Public health experts have warned that China is unprepared to live with the coronavirus, with just over half of people age 80 and older fully vaccinated as of late March.

In addition, China's leader, Xi Jinping, has held up the country's suppression of the virus as proof of the superiority of his governance model. Maintaining that line will be especially important this year, when he is expected to claim an unprecedented third term.

But in shutting down Shanghai, an economic engine that contributes 4 per cent of China's gross domestic product, the authorities have revived questions about the costs of their approach, especially in the face of the highly transmissible, relatively mild Omicron variant.

If even Shanghai could be cut off, people might worry there was no limit to how far the government would go, said Dr Lynette Ong, a political scientist at the University of Toronto.

"The fact that Shanghai is being locked down suggests that we are pretty close to the red line, to the tolerable limit of how defensible zero Covid is," Dr Ong said. "This is a big city with a 25 million population, and is extremely challenging to undergo lockdown - it's pretty close to people's psychological breaking point."

For most of the pandemic, Shanghai offered an alternate vision of China's containment strategy. While other places that detected even a few cases snapped into widespread lockdowns, Shanghai isolated individual buildings.

Dr Zhang Wenhong, an infectious disease expert who helped steer the city's response, attracted admirers nationwide for advocating a more restrained approach.

The Global Times, a nationalistic state-owned tabloid, praised Shanghai's "precise and targeted containment". Even after caseloads surged to record highs last month, officials insisted Shanghai could not be sealed off because of its economic importance.

But cases continued rising, and the central government probably grew nervous, said Dr Huang Yanzhong, director of the Centre for Global Health Studies at Seton Hall University.

"They were afraid maybe that if this situation cannot be under control in a short period of time, it's going to threaten social and economic stability," Dr Huang said. "It also might derail the leadership transition in the months to come."

The rollout of the more heavy-handed methods, however, has set off chaos, shocking a city with among the country's highest standards of medical care. At least two people with asthma have died after being denied care by health care workers citing Covid-19 protocols.

Patients with chronic illnesses have had operations indefinitely postponed or been unable to obtain medicine, forcing them to post desperate calls for help online. Care facilities for older adults are straining under outbreaks.

Whatever pride Shanghaiers had taken in their city's response has morphed into dismay and outrage. When local officials asked residents of one neighbourhood to sing patriotic songs to boost morale, they joined in a chorus of curses instead, according to footage circulated online.

After the authorities confirmed that they were separating infected children from their uninfected parents, a petition to allow children with mild or no symptoms to isolate at home garnered more than 24,000 signatures in three hours, before it was censored.

This week, residents in the Baoshan suburb struck pots and pans and shouted "We want supplies! We don't want to starve to death."

Some responses have been more lighthearted, though still reflecting the dire circumstances. Three local rappers wrote a viral song about panic-buying groceries.

Even city officials have expressed frustration with the new direction. In a leaked recording of a phone call between a Shanghai resident and a purported employee of the city's Centre for Disease Control, the staff member said she believed the approach to the epidemic had become politicised.

While officials did not confirm the authenticity of the recording, they later said they were investigating its contents.

Amid continuing backlash, officials have made some concessions, this week allowing certain infected children to stay with their parents and delivery drivers to return to work.

Dr Jin Dongyan, a virus expert at the University of Hong Kong, said Shanghai's educated, connected population was more primed than people elsewhere in China to be skeptical of the measures, especially given the lesser severity of the omicron variant. Chinese propaganda has often emphasised the dangers of the virus.

In Shanghai, "many people have a good understanding of the disease and of the virus, and also of what is happening in other places" that have retreated from the harshest restrictions, Dr Jin said.

"They just don't feel that this is going to work." Mr Jeremy Wu, 26, a Shanghai native, now wonders if he should have moved back to China from Australia, where he was in graduate school.

Mr Wu returned to Shanghai in the fall of 2020, believing that the city would be one of the few places in China where officials would keep cases low while avoiding excessive restrictions. When his friends in the northwestern city of Xi'an were locked down earlier this year, he felt relief at being in Shanghai.

"While sympathising with my friends, in my mind I was thinking, 'Thank God this would never happen to Shanghai'," Mr Wu said.

"What a 'da lian' moment that is for me," he added, using Chinese slang to suggest hitting oneself in the face when proven wrong.

Still, for all the dissatisfaction within Shanghai, support for zero Covid remains high in much of China. Nationalist social media users have accused the city of arrogance or lack of patriotism for pursuing its own approach at first. Even in Shanghai, some have said the city should have locked down sooner.

The central government has leaned into propaganda about the need for drastic steps in Shanghai, recently deploying more than 2,000 military medics and thousands more medical professionals from other provinces to the city.

Mr Chen Daoyin, a former assistant professor at the Shanghai University of Political Science and Law, said Beijing had clearly doubled down on zero Covid, and was bringing Shanghai in line with the rest of the country.

"In a system like China's, where politics determines everything," he said, "it's impossible for you to walk a different road."