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.

Confirmed measles cases in the U.S. reached 1,288, data from the Centers for Disease Control and Prevention showed on Wednesday, the highest since the childhood disease was declared eliminated from the country in 2000.

Measles cases in the United States are the highest they’ve been since the country eliminated the disease in 2000. The U.S. has reported 1,277 cases since the start of the year, according to NBC News’ tally of state health department data.