Texas reported 90 cases this week, while New Mexico reported nine. A majority of the cases have been in a Texas county where vaccination rates have lagged behind the rest of the state.

Lea County, New Mexico, is now reporting an outbreak of measles, according to the New Mexico Department of Health (NMDOH). Lea County is near Gaines County, Texas, where measles cases continue to rise as part of the original outbreak.

Health authorities warned of further spread. Most U.S. measles cases this year involved people 19 and under and those without a confirmed vaccination.