MIAMI — At the Florida community of The Villages, the retirement capital of America and the place with the nation’s highest concentration of older people, only 33 people have been tested for the coronavirus.

In the Florida Keys, swamped with young spring breakers and travelers from around the world, just 16 people had been tested by Monday night. Ten of Florida’s 67 counties have tested no one at all.

A disease that is deadly to the elderly and easily spread by the young has left Florida especially vulnerable. Yet faced with the prospect of dealing a shattering blow to an $86 billion tourism industry, Gov. Ron DeSantis has moved more slowly than some other states to contain a pandemic that is spreading with alarming speed. Whole swaths of the state have yet to begin robust testing, according to State Department of Health data. And even as some of the beaches still swarmed with college revelers, the state refused to close them.

In many cases, even people who have a known exposure or are exhibiting symptoms have not been offered testing, according to interviews with doctors, patients and family members across the state.