Shanghai, China’s largest city, has seen few cases until recently. Now, it is reporting more than 1,500 a day, and many residents are expressing anguish and dismay over China’s zero-tolerance approach to the virus.

On Friday, anger and grief welled up online after a Shanghai hospital confirmed reports that a nurse who worked there, Zhou Shengni, had died from an asthma attack after finding the doors of its emergency department shut because of Covid restrictions.

“Due to pandemic prevention needs, the emergency department of our hospital’s southern campus had been temporarily closed,” Shanghai East Hospital said on its website. Ms. Zhou’s family rushed her to another hospital, but she died late Wednesday after “attempts to save her failed,” Shanghai East said.

“Just think, this happened in Shanghai, and it was a medical worker treated like this,” read one of many comments about Ms. Zhou’s death on Weibo, a popular Chinese social media platform. “What about regular folks? Not just in Shanghai, but other parts too.”