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.

A measles outbreak in Kansas doubled in less than a week to 23 cases and has “a possible link” to outbreaks in Texas and New Mexico that have sickened more than 370, the state health department said Wednesday.

State health officials worry that declining vaccination rates have left many communities vulnerable nationwide.