KNOXVILLE (AP) — After confirming a case of measles in Tennessee, health officials say they are working to contact more than 600 people who may have been exposed to the highly contagious disease.

State health department spokeswoman Elizabeth Hart told the Knoxville News Sentinel on Monday that number includes both in- and out-of-state residents who may have come into contact with the infected person.

Health officials announced last week that one person in East Tennessee tested positive for the measles. Officials said only 15 other cases have been diagnosed in the state in the last decade. The largest and most recent outbreak consisted of seven cases in Shelby County in 2016.

The Centers for Disease Control and Prevention recommends that all children get two doses of measles vaccine, which is 97% effective.