The number of confirmed measles cases reported in an outbreak in West Texas is now at 124, the Texas Department of Health Services said in an update Tuesday, an increase of 34 since late last week.

Measles is a highly contagious airborne disease caused by a virus, and can be severe or even fatal. According to the U.S. Centers for Disease Control and Prevention (CDC), the best way to protect yourself against measles is to get vaccinated. Here, TIME answers all your questions about the vaccine.

It can spread rapidly in communities with low vaccination rates, and initially results in symptoms including a high fever, a cough, a runny nose, and red or watery eyes, according to the U.S. Centers for Disease Control and Prevention ( CDC ).

Health experts say low vaccination rates are fueling outbreaks of the contagious disease that was considered to be eliminated 25 years ago.

The measles outbreak that began in West Texas is still growing, with exposures possible as far away as San Marcos and San Antonio.

As of Feb. 20, there were a total of 93 measles cases reported in eight states: Alaska, California, Georgia, New Jersey, New Mexico, New York, Rhode Island and Texas, according to the Centers for Disease Control and Prevention. For comparison, 285 cases were reported in the U.S. in 2024.