Measles Can Ravage the Immune System and Brain, Causing Long-Term Damage

A biologist explains why people should take the disease — and vaccination — more seriously.

- Peter Kasson

The measles outbreak that began in west Texas in late January 2025 continues to grow, with 400 confirmed cases in the state and more than 50 in New Mexico and Oklahoma as at March 28.

Public health experts believe the numbers are much higher, however, and some worry about a bigger resurgence of the disease in the US. In the past two weeks, health officials have identified potential measles exposures in association with planes, trains and automobiles, including at Washington Dulles International Airport and on an Amtrak train from New York City to Washington, DC—as well as at healthcare facilities where the infected people sought medical attention.

Measles infections can be extremely serious. So far in 2025, 14 percent of the people who got measles had to be hospitalized. In 2024, that number was 40 percent. Measles can damage the lungs and immune system, and also inflict permanent brain damage. Three in 1,000 people who get the disease die. But because measles vaccination programmes in the US over the past 60 years have been highly successful, few Americans under the age of 50 have experienced measles directly, making it easy to think of the infection as a mere childhood rash with fever.