The number of measles cases in the U.S. has reached a 33-year record high, years after it was officially eliminated in the country, prompting public health experts to sound the alarm that other diseases could experience a similar resurgence.

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.

The measles outbreak has hit a new high, with over 1,200 cases reported in 2025 so far. The last time infections were that high was in 1992.