Ohio officials tracking more people who had contact with Ebola nurse

(CNN) – Frontier Airlines is trying to contact hundreds more passengers who flew with Amber Vinson, a Dallas nurse who treated an Ebola patient and then was diagnosed with the virus herself this week after flying round trip between Dallas and Cleveland.

A Centers for Disease Control and Prevention official said Thursday Vinson could have had symptoms earlier than believed – a time period possibly covering her two flights on Frontier Airlines.

Frontier said it is notifying as many as 800 passengers, including those on her October 10 flight to Cleveland, her October 13 return flight to Dallas, and five other trips taken by the plane before the airline took it out of service. Frontier said it's telling those passengers to contact the CDC – which had said the risk to anyone on the return flight was extremely low – if they have any concerns.

CNN's Susan Candiotti reports.