After weeks of record-high measles cases in the United States, signs of a slowdown are emerging — but health experts warn that the start of the school year could reignite outbreaks, especially in states with low vaccination rates.
“Back-to-school brings a lot of kids together and measles is very, very infectious,” said Dr. Catherine Troisi, an infectious disease epidemiologist at UTHealth Houston. “If you bring kids together and one of them happens to have measles, that’s just a great way to spread the virus.”
Texas, the epicenter of the year’s largest outbreak, hasn’t reported a new case in nearly a month. But the Centers for Disease Control and Prevention (CDC) reports that 89 new cases have been confirmed nationwide since July — pushing the 2025 total to 1,356, the highest in more than three decades. Out of 50 states, only 10 have reported zero cases this year.
Low vaccination rates remain a key driver of outbreaks. CDC data shows that just 84.8% of Wisconsin kindergartners received the recommended two doses of the measles-mumps-rubella (MMR) vaccine last school year, far below the 95% threshold needed to prevent outbreaks. Only Alaska and Idaho reported lower coverage rates.
Wisconsin is also one of 15 states that allow vaccine exemptions for personal beliefs, and its exemption rate is more than double the national average. The American Academy of Pediatrics has reiterated its stance that such nonmedical exemptions should be eliminated, warning that they “threaten the safety of the entire school community.”
New outbreaks continue to emerge. Michigan’s Osceola County recently confirmed a case linked to out-of-state travel, marking the state’s third outbreak this year, with at least 27 cases total. Wyoming reported four new cases in Carbon County, an area with some of the lowest childhood vaccination rates in the state.
Experts say local action is critical. County-level vaccination rates often reveal pockets of vulnerability, where sociocultural factors cluster unvaccinated individuals. Outbreaks in these communities can quickly spread to other low-coverage areas.
Public health officials are urging schools to use the back-to-school period to promote vaccination through on-site clinics and trusted messengers like school nurses. “Making vaccines accessible at school and having respected community figures talk about their importance can help boost coverage,” Troisi said.