The outbreak that originated in Texas has spread into multiple states. And, the summer will be the real test of how much bigger this outbreak can grow.

The measles outbreak that started in the South Plains region of Texas surpassed 700 cases on Tuesday, according to health officials. The latest update from the Texas Department of State Health Services shows the state has seen 702 cases of measles since the outbreak began spreading in late January.

There are more than 930 confirmed cases of measles across the U.S. as of Friday, according to the Centers for Disease Control and Prevention, with a majority of the highly contagious illness present in Texas.