While measles symptoms typically resolve in a few weeks, the virus can cause pneumonia, making it difficult for patients, especially children, to get oxygen into their lungs. It may also lead to brain swelling, which can cause lasting damage, including blindness, deafness and intellectual disabilities.

There are 1,288 measles cases throughout 38 U.S. states so far this year, which is the most since 1992, according to new data from the CDC released this week.