The measles vaccine has been proven to be safe and effective against the disease, which is highly contagious and can be life threatening.

But there's a silver lining, officials say: More people have received a measles, mumps and rubella vaccination this year in Texas and New Mexico, which also has an outbreak, compared to last year — even if it's not as high as they would like. And pharmacies across the U.S., especially in Texas, are seeing more demand for MMR shots.