The measles outbreaks in West Texas and New Mexico have surpassed a combined 350 cases, and two unvaccinated people have died from measles-related causes. Measles is caused by a highly contagious virus that's airborne and spreads easily when an infected person breathes,

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.

The Texas measles outbreak has grown to 309 confirmed cases, not counting dozens of additional cases in neighboring states. Cases have been identified in three additional counties, according to the Texas Department of State Health Services' Friday update.