The United States has confirmed more measles cases so far in 2026 than in any year in more than three decades, as outbreaks continue to spread in multiple states, according to data from the Centers for Disease Control and Prevention.
By mid-July, the national case count had already surpassed the total for all of 2025, which had stood as the worst year in recent history with more than 2,200 confirmed infections. By October, the number of cases had climbed past 4,500. The ongoing outbreaks have put the country at risk of losing its official measles elimination status, a designation the United States has held since 2000.
In August, health officials in Pennsylvania reported the state's first deaths connected to measles in 35 years, both in Lancaster County. State health officials said both individuals had not been vaccinated against the virus, and several more deaths associated with measles were later reported as the state's outbreak surged.
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. The disease can be prevented through vaccination, which medical research has proven to be safe and highly effective.
Of the 2,289 confirmed cases recorded last year, more than 750 were connected to an outbreak in West Texas that led to the deaths of two children. Before 2025, the highest number of confirmed cases in the country in recent years was 1,274 in 2019, driven by outbreaks in New York, California and Washington state. In most years, the national total was much lower.
Health experts point to declining vaccination coverage as the main reason for the increases in 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 the share of children in the U.S. who received their measles, mumps and rubella shots in the 2025-2026 school year slipped slightly from 92.5% the previous school year. The figure has declined from 95.2% during the 2019-2020 school year, and only 10 states reached 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.
Dr. Jay Bhattacharya, the director of the National Institutes of Health, emphasized the importance of childhood immunization. "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," he said.
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.
