Of those infected across the U.S., 97% of cases came from those who are unvaccinated or whose vaccination status is unknown.

The Texas health department reported 561 cases of measles in the state on Tuesday, an increase of 20 from April 11, as the U.S. government said it was sending seven people to the state to help battle the outbreak of the childhood disease.

Measles has been confirmed in a Los Angeles County resident who recently returned from Texas, health officials said Friday.