Measles is a respiratory virus that can survive in the air for up to two hours. Up to 9 out of 10 people who are susceptible will get the virus if exposed, according to the U.S. Centers for Disease Control and Prevention.

A measles outbreak in the southwestern United States has infected nearly 100 people in recent weeks. The deadly illness has sickened dozens of people in west Texas and New Mexico since late January. The Texas Department of State Health Services confirmed 90 cases of measles,

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.