The measles outbreak that began in the South Plains region of Texas rose to 422 cases and spread to two new counties on Tuesday, according to health officials. The update from the Texas Department of State Health Services added 22 infections since the agency’s last update on Friday.

The Texas public health department is now reporting a total of 422 measles cases in the ongoing outbreak that began in Gaines County. The outbreak has now spread to two additional counties, both in the center of the state.

The Texas health department said on Friday that the number of measles cases in the state rose 20% since its last report three days ago, as experts warn they expect the outbreak to further spread in coming weeks.