Dallas Classrooms Fall Below ‘Herd Immunity’ Level for Measles Protection

Students attending Dallas-area schools are less likely to be vaccinated against measles than they were five years ago, posing a risk to herd immunity amid increased outbreaks of the disease, an analysis of school vaccination data by The Washington Post found. 

The investigation analyzed state-specific vaccination record data from pre-COVID school years and the 2024-2025 school year to track vaccination rates. Texas has recorded a 4% decline in the number of kindergarteners vaccinated against measles, mumps, and rubella — the trio of diseases treated by the MMR vaccine, which is required for kindergarten enrollment — dropping from 97% to 93% statewide. That is the lowest Texas’ MMR vaccination rate has been since at least 2011.  

Doctors widely believe that a 95% vaccination rate is necessary to achieve “herd immunity,” the threshold that prevents the spread of a particular disease and helps protect individuals who cannot be vaccinated, whether due to age or immunocompromising conditions. For many Dallas-area classrooms, the vaccination rate is far below the state’s average. In the data Texas reported to Washington Post investigators, public schools are grouped into an overall, district-wide percentage, while private schools were reported individually. 

In Dallas ISD, 78.9% of kindergartners were vaccinated against measles last school year, the report found, a more than 20% delinquency rate. Arlington ISD, on the other hand, reported a 94.8% vaccination rate, while Fort Worth ISD saw 95.4% of kindergarteners receiving the MMR vaccine. 

Private schools across Dallas reported some of the lowest rates of MMR vaccination. Just 53% of kindergartners at St. Cecilia Catholic School in Oak Cliff were vaccinated against measles during the last school year, according to state data, the lowest rate in Dallas County. Of the 26 Dallas County private or charter schools that did not achieve herd immunity levels of vaccination last year, 18 are affiliated with a religion. 

Religious exemptions are one of two ways Texas allows parents to opt out of vaccination requirements. The state also allows for medical exemptions. Between 2018 and 2024, the number of school vaccine exemption forms submitted to the Texas Department of State Health Services doubled, according to the Texas Tribune. Some experts expect that number to continue growing thanks to a new state law that went into effect on Sept. 1, which allows families to download the exemption form rather than request it. 

​​“It’s crazy that we’ve been going through these record measles outbreaks, this situation for Texas, and then still the legislature passes a law that makes it easier for parents to get an exemption from vaccines,” Dallas County HHS Director Philip Huang told the Observer earlier this year. 

The United States recorded more than 2,000 measles cases in 2025, the first time the number has grown that large since 1992, according to the Centers for Disease Control and Prevention. More than 90% of those cases were among people who were not vaccinated against the disease or had an unknown vaccination status. Nearly half of those cases traced back to a West Texas outbreak that sickened 762 Texans and killed two children who lived in a Mennonite community. 

Vaccine skepticism that took root during the pandemic — more than 80% of local health departments surveyed by the National Association of County and City Health Officials in 2023 reported a post-COVID-19 rise in vaccine hesitancy — has also, increasingly, become partisan.

While the Post found that 5.2 million U.S. children are living in counties without herd immunity status against measles, a disproportionate percentage of declining vaccination rates was recorded in counties that voted for President Donald Trump in 2024. Trump’s appointed Health Secretary, Robert F. Kennedy Jr., has rolled back some vaccination guidelines in the last year and has previously stated anti-vaccination conspiracies. 

“We have very different levels of health and protection based on ZIP codes, and children don’t get to choose where they live or where they go to school,” Susan Kressly, president of the American Academy of Pediatrics, told The Washington Post. “For pediatricians, immunization is a child health priority, not a partisan issue.”