In Solon, Ohio, 20 miles southeast of Cleveland, two schools will shut down Thursday so health officials can disinfect the buildings. The school district stated in an e-mail that it made the call after learning a local middle-school staff member may have been on the same plane — but not the same flight — as Vinson.

Some 1,200 miles away in Belton, Tex., about an hour north of Austin, a school district came to the same conclusion. The school district announced via Twitter that three of its schools would be closed Thursday. And two children who were on the same Frontier flight have been asked to stay home from school for 21 days and monitor their temperatures.

The elementary-school student and middle-school student showed up to school Tuesday and Wednesday, but were not showing symptoms of the disease. “Because of this, there is no imminent risk to your child,” school officials said in letters sent home to parents. Belton Superintendent Susan Kincannon said during a news conference both students are considered low risk, but “we anticipate that some parents will choose to keep their children at home.”

And a student in the Eagle Mountain-Saginaw school district — in a county bordering Dallas — will be isolated with his or her family for three weeks after the shared flight.