More than half of U.S. counties have seen a steady increase in vaccine exemptions for religious or personal beliefs among kindergartners in the years since the COVID-19 pandemic, according to a new analysis led by NBC News and Stanford (Calif.) University.
The study, published Jan. 14 in JAMA, is based on data from 3,053 counties and jurisdictions across 45 states and the District of Columbia, spanning from 2010 to 2024.
For the 2023-24 school year, the median rate for nonmedial vaccine exemptions among kindergarteners was 3.1% — up from 0.6% in 2011-11. Researchers also found more than 53% of counties saw an increase of at least 1 percentage point in nonmedical vaccine exemptions.
“These may look like small numbers, but they may be enough to be the tipping point for something like measles,” Nathan Lo, MD, assistant professor of infectious diseases at Stanford and a co-author on the study, told NBC.
The findings come as the U.S. sees its worst measles outbreak in decades. The nation is on track to lose its measles elimination status — which it has held since 2000 — in the coming weeks as outbreaks grow in some parts of the country. More than 2,400 cases have been confirmed in the U.S. since 2025, including 171 so far this year, according to CDC data. The majority of cases have occurred among unvaccinated children.
Three more notes on measles vaccination uptake:
1. Utah, Idaho, Oregon, Wisconsin and Arizona had the highest rate of nonmedical exemptions after the COVID pandemic, according to the new analysis. In parts of Oregon and Utah, exemption rates exceeded 20%.
2. The CDC recommends at least 95% of a community be vaccinated to achieve herd immunity for highly contagious diseases like measles. For the 2024-25 school year, 92.5% of kindergartners received the MMR vaccine — down from 95.2% before the pandemic.
3. The American Academy of Pediatrics in July 2025 called upon lawmakers to eliminate nonmedical exemptions, citing public health and ethical concerns. The group warned that rising exemptions and patchwork state laws are undermining herd immunity and increasing the risk of outbreaks.
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