In Mississippi, where one health officer called adherence to social distancing over the past weeks “overwhelmingly disappointing,” officials attributed clusters of new cases to fraternity rush parties.

Texas Gov. Greg Abbott said last week that people under 30 made up a majority of new coronavirus cases in several counties. He said that increase in young infected people could be related to Memorial Day parties, visits to bars or other gatherings.

And in Florida, Gov. Ron DeSantis said Friday that the median age was 37 for newly diagnosed coronavirus cases over the last week. In the state, 62% of new cases for the week of June 7 are under 45 years old, he said.

“That is a big change from where we were at the end of March and the beginning of April. It was skewing much older at that time,” he said.