The effectiveness of the vaccine, coupled with rising vaccination rates, led to such low rates of measles that it was declared eliminated in the U.S. in 2000. In recent years, though, the virus has made a resurgence, as childhood vaccination rates have dropped nationwide.

State and local health officials are urging individuals to receive MMR vaccine as Texas reaches 124 cases this week. Here is what we know.

A young unvaccinated boy with measles died in Texas overnight, the Texas Department of State Health Services announced Wednesday, the first fatality in the U.S. from the respiratory disease in a decade.