A measles outbreak in Utah has sickened more than 670 people, including many children whose parents have chosen not to vaccinate them. But new data shows that people who can’t be vaccinated for various health reasons are also falling ill.
Since the outbreak began last summer, measles has infected 23 babies under age 1, the age when children typically receive the first dose of the measles, mumps and rubella shot. Twelve pregnant women have also been infected, including one who passed the virus on to her newborn, according to data from the state health department.
While the state keeps only limited data on the number of immunocompromised residents who have fallen ill, pediatric infectious disease doctors also say they have cared for several immunocompromised children hospitalized with measles infections.
These patients still represent a minority of the unvaccinated people who have been sickened. Still, these findings are concerning because many of the groups who can’t get the vaccine are also at high risk of developing severe complications from the virus. Pregnant women, for example, are 10 times more likely to die from measles than those who are not pregnant. The virus can also cause women to miscarry or go into labor prematurely.
Young children are more likely to suffer severe complications from the virus. And babies who contract measles before their first birthday are at much higher risk of developing a rare condition called subacute sclerosing panencephalitis that can occur years after an initial infection. Dr. Andrew Pavia, an pediatric infectious disease specialist in Utah, described the complication — which can cause seizures, motor issues and eventually death — as “one of the most horrible things I’ve witnessed.”
Health officials in the state have advised parents to consider an extra, early dose of the measles vaccine for babies between 6 and 11 months old because of the risks of infection.
Even vulnerable people who have avoided infection have faced major disruptions. Earlier this year, a state health official said 130 babies, too young to be vaccinated, received injections of an antibody treatment after they were exposed to the virus in doctors’ waiting rooms.
Dr. Trahern W. Jones, a pediatric infectious disease doctor in Salt Lake City, said he feared for the children in the state who were undergoing chemotherapy, or who had an autoimmune disease or another condition that made their bodies unable to mount a strong defense against the virus.
“If they catch measles, it’s really, truly life-threatening,” he said. “I would say it’s hazardous being an immunocompromised person in Utah right now.”
The measles vaccine provides strong protection against infection, but because it contains a weakened version of the measles virus, it cannot be given to babies or those with compromised immune systems. Doctors also recommend against giving it to pregnant women out of a theoretical concern that the virus could cross the placenta and infect the fetus.
Historically, these groups have relied on the communities around them to have high vaccination rates to keep measles outbreaks at bay.
But in recent years, holes in that safety net have emerged. In the 2024-25 school year, about 11 percent of kindergartners in Utah had exemptions or were missing documentation to show they were vaccinated against measles, up from about 7 percent before the Covid-19 pandemic. This mirrors a national drop in childhood vaccinations that began during the pandemic.
While Utah is the latest state affected by the resurgence of measles in the United States, a series of large outbreaks have popped up around the country since 2025, including in Texas, Florida and South Carolina.
Measles cases reached a record high last year as the country reported more than 2,200 infections. Experts expect this year’s case count, already at 1,952 nationwide, to surpass that. In November, a panel of international experts is expected to meet to 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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