So far in 2026, the U.S. has recorded the most measles cases in more than three decades as outbreaks spread in multiple states, Centers for Disease Control and Prevention data shows. 

By mid-July, the number had already surpassed all of 2025, which had been the worst year in recent history with more than 2,200 confirmed cases. Ongoing outbreaks have put the U.S. at risk of losing its official measles elimination status, which it has held since 2000. 

Measles is one of the most contagious infectious diseases. In some cases, it can cause severe infections in the lungs and brain that can lead to cognitive issues, deafness or death. But it can be prevented by vaccination, which medical research has proven to be safe and highly effective.

The CBS News data team has tracked confirmed measles cases nationwide as new data is released by state health departments and the CDC. 

Out of the 2,289 confirmed cases last year, more than 750 were connected to an outbreak in West Texas that led to the deaths of two children. 

Prior to 2025, the highest number of confirmed cases in the U.S. in recent years was 1,274 in 2019, driven by outbreaks in New York, California and Washington state. Most years the total was much lower. 

Health experts point to lower vaccination rates as the main reason for increases in preventable infectious diseases like measles. The vast majority of cases have been in people who were unvaccinated, and outbreaks have spread in communities with lower vaccination rates.

CDC data shows about 92.5% of kindergartners in the U.S. were vaccinated against measles during the 2024–2025 school year. That's down from 95.2% during the 2019-2020 school year — a critical threshold to keep people safe. Only 10 states hit the 95% threshold last year.

"When more than 95% of people in a community are vaccinated, most people are protected through community immunity (herd immunity)," the CDC states.

"I think that parents, for most kids, especially for the measles vaccines, the DTP, all the standard childhood vaccines, it's very important that parents vaccinate their kids," Dr. Jay Bhattacharya, the director of the National Institutes of Health, said on "Face the Nation with Margaret Brennan."

Research has found no evidence of increased rates of autism among those who are vaccinated compared to those who are not. Vaccines also undergo intensive safety testing.

Edited by Paula Cohen and Melissa Gaffney

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• Measles