“We are trying to flatten the curve — in the city and the country — but a neighborhood has to think that way, too,” Mr. Menchaca said.

Mayor Bill de Blasio has applauded the efforts of New Yorkers to help each other. But a sense of alarm has grown in recent days as the number of confirmed cases of coronavirus in New York has increased. As of Tuesday morning, New York State had more than 25,000 cases, with almost 15,000 of those in densely-packed New York City.

The city’s health department said in a statement to The Times that New Yorkers could help each other most by connecting by phone and video to offer “emotional support.” If a sick neighbor needs groceries, the city advised to “leave them on the door step.”

Javier López, the chief strategy officer with the Red Hook Initiative, a youth development organization, said the ways of helping that developed after Hurricane Sandy hit the neighborhood in 2012 have had to be “tweaked."

Staffers from the initiative have been working through a list of 2,000 phone numbers for residents of the Red Hook Houses, one of the largest public housing projects in the city, to create a map for who might need help.

“But throughout the process,” he said, “there is hesitancy. This is not Sandy. This is different. It’s a different response. They’re checking in through social distancing.”

When it comes time to distribute food and supplies, he added, there will not be central collection spots as there were after Sandy.