Then Ms. Zhang’s grandfather, already weak from lung cancer, suddenly took a turn for the worse. He had been using an oxygen machine to support his breathing for 30 minutes in the morning and again at night. Now he couldn’t breathe at all, and needed to be hooked up to the machine around the clock. He came down with a high fever. For four days he was so uncomfortable that he couldn’t sleep, Ms. Zhang said.

Desperate to find help, Ms. Zhang and her family called everyone they could think of. But the hospitals were all full. Emergency responders told them they needed to secure a hospital bed first before an ambulance could be sent.

Ms. Zhang was devastated to see her grandfather, who had helped raise her, nearing death. Overnight, her social media feed, normally full of food and travel photos, became a flood of urgent cries for help. In a last-ditch effort, she called a hotline for the city’s mayor. But an operator had no answers, and asked her what they planned to do.

“You’re asking me, an ordinary citizen, how to resolve this?” she replied. She hung up.

That afternoon, her grandfather died in the family’s apartment.

Workers from a funeral home arrived to take his body away. They said that because he had possibly been infected with the virus, the family was not allowed to accompany the body and it had to be cremated immediately.

But they had no time to mourn. Ms. Zhang’s grandmother was now deteriorating rapidly. They took her to a hospital, where a doctor said that her lungs appeared on a CT scan as almost entirely white — signs of severe pneumonia. She later tested positive for the coronavirus.