Kansas health officials have confirmed 23 measles cases, marking an outbreak for the state as infections in at least 17 states have led to the most cases in the U.S. in a single year since 2019. The Kansas outbreak is spread across 6 southwest counties, the state's Department of Health and Environment said Wednesday.

Twenty-three measles cases have been reported in Kansas, and the state health department said they could be linked to an ongoing outbreak that has infected at least 379 people across Texas, New Mexico and Oklahoma.

Most of the public school districts in the Kansas counties experiencing the outbreak have vaccination rates well below the recommended 95% threshold.