Frontier Airlines says it is notifying passengers on seven flights that they either flew with a nurse who later tested positive for Ebola or on a later flight using the same plane.

That includes a flight from Dallas to Cleveland last Friday, one from Cleveland to Dallas on Monday night, and five other flights with the same aircraft on Tuesday.

The airline said Thursday that it was telling those passengers to contact the Centers for Disease Control and Prevention if they were concerned. The CDC has downplayed risk of exposure to other passengers.

Frontier grounded the plane on Wednesday after the CDC notified the airline that a passenger, Amber Joy Vinson, had tested positive for Ebola. The plane is currently out of service in a hangar at the Denver airport.

Photo Credit: A Frontier aircraft on the tarmac. Brian Sumers / Skift