“People were upset,” said Ms. Quigley, who leaves Sunday, adding that many of her friends at other schools had now canceled their upcoming spring break plans. “People were on the phone with their parents trying to figure out what to do. It was clear how serious the coronavirus had become.”

As the cases mounted, city leaders met with health officials to formulate strategies that would reduce the risk of the virus spreading. Large public events like Ultra Music Festival and Calle Ocho were quickly canceled. But spring break is tricky because it is not made up of a single event and students visit beaches from Panama City to Key West.

The outbreak forced hard public health questions: What are the potential risks of thousands of students descending on the state’s beaches and crowding into bars and restaurants? Can spring break during a pandemic be safe? And with two weeks left in the spring break season, should state and local leaders try to slow the waves of young people who could potentially arrive and then spread the virus across the country?

“Young people who are on spring break are not just sitting having conversations. They are going to multiple places, they are going to parties, they are touching and kissing, they are drinking,” Dr. Lilian Abbo, chief of infection prevention for Jackson Health System and a professor of infectious diseases at the University of Miami Miller School of Medicine, said on Wednesday. “We can’t stop people from coming here for spring break, so we have to send a consistent message: Do not come into public spaces sick, practice social distancing.”

Last Monday, the governor declared a state of emergency. That same day, Ben Cunningham was in Ohio making his mother a promise before he hopped onto a plane to Florida for spring break: He would wash his hands frequently, wipe down surfaces and keep the pocket-size hand sanitizer in his backpack.