In February, a six-year-old Texas girl died from measles. It was the first measles death in the U.S. in 10 years.

The girl wasn’t vaccinated. Neither were her four siblings. They all caught the measles, too. Luckily, they survived.

The Texas outbreak started in January. Before long, more than 1000 measles cases were reported in 31 states. And 96 percent of the people infected were not immunized.