Measles Outbreak Risk Rises in US Schools Despite High Regional Vaccination Rates

A recent study published in Nature Medicine warns of an increased risk of measles outbreaks in US schools due to uneven vaccination coverage. Researchers from Cornell University analyzed MMR vaccination data from over 50,000 schools across 45 states and Washington D.C. between 2013 and 2025. Their model revealed that by the 2022-2023 school year, the threshold for measles outbreaks had already been crossed at the individual school level, despite seemingly adequate vaccination rates at the district or regional levels.

The study highlights that average high vaccination coverage can mask small, concentrated pockets of unvaccinated children, which significantly raise the risk of outbreaks. The proportion of children susceptible to measles nearly doubled after the COVID-19 pandemic, increasing from about 5% to 10%. Furthermore, administrative boundaries do not necessarily protect well-vaccinated areas, as movement between schools and districts can facilitate virus spread from low-coverage to neighboring populations.

The researchers recommend that measles monitoring and vaccination efforts focus not only on national or district levels but also at the school and education district levels to identify and address clusters of unvaccinated children early. Although the study focuses on the US and does not assess Israel's situation, it underscores the public health principle that high overall vaccination rates do not guarantee uniform protection across all communities.