Measles cases are surging across the U.S., and a new analysis reveals a troubling trend: vaccine exemptions are on the rise in more than half of American counties. It’s a stark reminder that preventable diseases aren’t relics of the past—they’re poised for a comeback if we let them.
Exemption Rates Climb, Fueling Measles Resurgence
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More U.S. counties are seeing parents opt out of childhood vaccinations, leaving communities vulnerable to outbreaks of diseases like measles.
- Vaccine exemption rates have increased in over half of U.S. counties since the start of the COVID-19 pandemic.
- Nonmedical exemptions—based on personal or religious beliefs—are the primary driver of this increase.
- The science supporting vaccine safety and efficacy remains unchanged, experts emphasize.
- Areas with higher exemption rates are experiencing localized outbreaks, like the ongoing measles surge in South Carolina.
What’s driving this shift? The decision to forgo vaccines isn’t typically about medical necessity. Researchers found that exemptions for medical reasons—for those who are immunocompromised or have severe allergies, for example—have remained stable. Instead, it’s a growing number of parents citing nonmedical reasons, often described as religious or personal beliefs.
The new analysis, published Wednesday in the medical journal JAMA, compared vaccine exemption rates among kindergartners before and after the pandemic. The data, covering nearly 90% of U.S. counties, showed the median rate of nonmedical exemptions increased from 0.6% in 2010-2011 to over 3% in 2023-2024. Approximately 53.5% of counties saw nonmedical exemptions rise by at least 1% between 2010-2020 and 2021-2024, with over 5% experiencing an increase of at least 5%.
The U.S. Centers for Disease Control and Prevention suggests this increase is linked to growing “vaccine hesitancy.” A summer 2024 survey by the agency found that while most parents support school vaccine requirements, those seeking exemptions most often cited philosophical or personal beliefs—reported by more than a third of parents. Difficulty meeting school deadlines was a factor for about 23%, while medical reasons were cited by over a quarter, though the CDC notes some may categorize vaccine safety concerns as “medical” reasons.
Dr. Nathan Lo, an infectious disease physician and scientist with Stanford and author of the research, emphasizes that even small differences in vaccination coverage can have a significant impact. “When you look at national trends, or even state level trends, in many ways they’re very optimistic because they miss whole pockets of communities and counties where vaccine coverage may be low and vaccine exemptions may be high,” Lo explained. “Really it’s those pockets that drive the outbreaks of vaccine preventable diseases that we see across the nation.”
South Carolina Outbreak Highlights the Risk
The consequences of declining vaccination rates are playing out in real-time in places like Spartanburg County, South Carolina. The county is currently at the center of a large measles outbreak, with nearly 8% of children having nonmedical exemptions in 2024—a significant jump from 2% in 2014.
The South Carolina measles outbreak has more than doubled in size over the past week, with state health officials now reporting over 400 cases. At least 400 others are in quarantine due to exposure, and officials anticipate further cases. The outbreak began growing rapidly in early October, with exposures reported at schools, churches, and public locations, including the South Carolina State Museum in Columbia.
State health officials attribute the outbreak’s spread to holiday activities—school breaks, gatherings, and travel—particularly in areas with low vaccination rates. “The (undervaccinated) pockets are all interconnected,” Lo said, “through geographic proximity and the nature of our society. When you think about the places with really large (vaccine exemption rates), I think the pockets are getting a little bit bigger and are becoming more numerous.”
The vast majority of measles cases in the current outbreak—92%—are among children, and nearly all are unvaccinated with the measles-mumps-rubella (MMR) vaccine, according to state health data.
Communities with high exemption rates are particularly vulnerable to localized epidemics, Hackell warns. But the risk extends beyond those areas. “If you’ve got a whole bunch of kids in one of these counties with high exemption rates who are getting sick and have the opportunity to travel the surrounding areas, even those counties with lower exemption rates are going to see a rise in cases,” he said. “You’ve got a lot more people around who can spread the diseases to people who may be susceptible.”
Cases in North Carolina have been linked to travel from Spartanburg County, and the New Mexico health department has warned of potential exposure in Albuquerque from a visitor from South Carolina.
State Policies and the Path Forward
A few states—including California, Connecticut, Maine, and New York—have eliminated nonmedical vaccine exemptions, and the new research shows these counties saw an increase in vaccine coverage. Conversely, Florida recently moved to end all vaccine mandates, including for school attendance.
Experts agree that legislative action is the most effective large-scale intervention. Increasing vaccination coverage will also depend on individual conversations between families and their doctors and consistent public health messaging. “The vast majority of parents in most places choose to immunize,” Hackell said. Nationally, 3.6% of kindergartners had an exemption in the 2024-25 school year, federal data shows—meaning over 96% were vaccinated.
“A parent who chooses to vaccinate their child is not being careless or thoughtless or weird,” Hackell added. “The social norm is to immunize and protect your child and, by extension, protect the children around them. The social norm is vastly in favor of immunizations, and that reflects the science.”
