Utah has become a hotbed of measles cases in the United States, as a long-simmering outbreak continues to spread.
There have now been nearly 600 cases, mostly in children, since the outbreak began along the Utah-Arizona border last summer. Roughly one-third of those diagnosed have been so sick that they sought treatment in emergency rooms, mainly for severe dehydration caused by vomiting and diarrhea. So far, 49 people have been hospitalized.
Dr. Trahern W. Jones, a pediatric infectious disease doctor in Salt Lake City, said he had cared for a handful of children who arrived at the hospital gasping for breath. The virus can cause a number of respiratory complications, including pneumonia.
For more than a year, large measles outbreaks have popped up all over the United States, in places including Texas and South Carolina. But unlike those outbreaks and many of others over the last two decades — which have often had ties to insular religious communities, like Mennonite, Amish and ultra-Orthodox Jewish groups — the virus appears to be spreading through the broader population in Utah.
The virus has jumped between under-vaccinated groups of people across the state. Dr. Leisha Nolen, the Utah state epidemiologist, said that measles cases had emerged in 22 of the state’s 29 counties. Most of the counties that have been spared have very small populations, she added.
While Utah requires that public school students have two doses of the measles, mumps and rubella vaccine, parents can opt out of those requirements for personal, religious or medical reasons. In the 2024-25 school year, about 11 percent of kindergartners had exemptions or were missing documentation to show they were vaccinated against measles, up from about 7 percent before the Covid-19 pandemic. Vaccination rates need to be above about 95 percent to stem the spread of the virus.
Many of the families Dr. Jones has seen in the hospital for measles are not staunchly opposed to vaccines; they have often have delayed shots because of their concerns about the side effects. The M.M.R. vaccine is considered very safe and about 97 percent effective in preventing infection.
“There’s so much misinformation out there,” he said. “They get way more information about the side effects of vaccines than they ever get about what can happen if you catch one of these diseases.”
Part of the problem, he said, is that politicians have sent mixed messages about the importance of vaccination. Utah state lawmakers even introduced legislation this year that would have made it easier to opt out of school vaccination requirements. Though it did not become law, he said the fact that it had been introduced during the middle of a measles outbreak incensed doctors on the front lines.
“It’s kind of like if you were a firefighter trying to put out a house fire, and somebody is standing on the hose trying to have a philosophical debate with you about whether water is good or not,” he said.
While measles cases in Utah appear to be ticking down, Dr. Nolen said it was too soon to say whether the outbreak was past its peak, especially since students had recently come back from spring break.
Dr. Nolen said that the outbreak still posed such a threat to children that her office had made the unusual recommendation that all Utah parents consider an extra, early dose of the measles vaccine for any infant between 6 months and 11 months. Children typically get their first M.M.R. vaccine at 1 year old, and historically, public health officials have recommended early doses only for children traveling abroad or living near an active measles outbreak.
Some parents of babies too young for even the early dose are avoiding going out in public until they become eligible, said Dr. Ellie Brownstein, a pediatrician in Salt Lake City and president-elect of the Utah Chapter of the American Academy of Pediatrics.
There have been several instances in which babies who were too young to be vaccinated were exposed to measles in doctors’ waiting rooms, Dr. Nolen said. At least 130 of these children received injections of an antibody treatment, which can lessen the severity or prevent an infection if given within six days of exposure.
“You could take your baby in for an ear infection and get them exposed to measles,” Dr. Nolen said.
The outbreak comes during a challenging period in the nation’s public health. The number of measles cases hit a 34-year high in 2025, and the country is on track to surpass that record this year. In November, a panel of international experts will consider whether measles can still be considered “eliminated” in the United States, as it has been for 26 years.
Teddy Rosenbluth is a Times reporter covering health news, with a special focus on medical misinformation.
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