Measles cases in the United States have reached their highest number in more than 30 years, according to new federal data published Wednesday.

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.

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.