When deaf residents became sick, they found it hard to communicate with medical workers. Most Chinese hospitals are unable to provide sign-language services, even when they are not as strained as the Wuhan and Hubei hospitals have been.

Amy Ye, the organizer of a volunteer group for disabled people in Wuhan, said that as soon as Wuhan was locked down, her organization asked local community workers to look out for disabled people. But they were too overwhelmed. The volunteers tried to help disabled residents themselves, but gave up because public transportation had been shut down.

“The whole city was paralyzed,” Ms. Ye said.

Like Ms. Zhang, Ms. Ye, who uses a wheelchair, lives on a monthly government stipend. She spends nearly a fifth of it, about $30, on prescription drugs for her high blood pressure, the cheapest she can find. And food costs have soared. A cucumber costs nearly $1 now, and the price of pork has tripled since a year ago.

“My family has always been treading on thin ice financially,” she said. “I want this to be over as soon as possible.”

Community workers in many neighborhoods in Hubei have turned to mobile apps to share information and organize grocery shopping for residents. The most widely used app is the social messaging service WeChat, which hundreds of millions of Chinese use to communicate, pay and shop.

But many older people aren’t familiar with WeChat or fluent in all of its functions. Many are lost when they have to use their phones to shop for food.

Hu Jing, a Wuhan resident who has been doing volunteer work over the past month, said that in one six-hour shift at an apartment compound, about a dozen older people came to her complaining that groceries were too expensive, or that they didn’t know how to order them online.