Did New Yorkers Who Fled to Second Homes Bring the Virus?

“We are a small community on Fire Island. The fire department is not there, there are no medical people over there,” Mr. Sherman said. “It was the prudent thing not to run at all. We are protecting it.”

Nevertheless, he said he had watched some people cross from the mainland in private boats.

And in Cape May, where the 30-year-old man from New York City tested positive at a local health care facility while visiting, year-round residents regularly call the offices of elected leaders to report out-of-state plates, according to a government official familiar with the calls.

“Folks from out of state need to understand the critical need to follow stay-at-home orders,” said State Senator Michael L. Testa Jr., a Republican who represents New Jersey’s southernmost district, which cuts across Cape May and Atlantic Counties. “It’s up to them to save their fellow Americans.”

The push to keep New Yorkers at their primary residences extends beyond the metropolitan area: Late last month, the governor of Florida, where many New Yorkers have vacation homes, mandated a 14-day quarantine for anyone who had arrived from the New York region in the previous three weeks.

Similar concerns have even cropped up internationally: On Sunday, Scotland’s chief medical officer resigned after it emerged that she had violated the country’s lockdown rules by visiting her second home by the sea.

The deluge has sent resort towns scrambling to prepare for the virus. Stony Brook Southampton Hospital said it had tripled its number of intensive care beds, to 21, and hired 40 additional nurses, housing them in a local hotel.

Catskill, a village about 35 miles south of Albany, has been training its public works employees to drive ambulances and operate its ladder truck in preparation for a run on services, said Vincent Seeley, the village president.