U.S. Faces Largest Measles Outbreak in Over 30 Years Due to Declining Vaccinations

The United States is experiencing its most significant measles outbreak in over three decades, with 1,309 confirmed cases reported across 40 states as of July 15, 2025. This resurgence, which began in January in West Texas's Gaines County—a region with notably low vaccination rates—has resulted in three confirmed deaths: two children in Texas and one adult in New Mexico.

Measles, a highly contagious viral disease, was declared eliminated in the U.S. in 2000. However, declining vaccination rates have facilitated its return. The Centers for Disease Control and Prevention (CDC) reports that MMR (measles, mumps, rubella) vaccination coverage among kindergartners has fallen below the 95% threshold necessary for herd immunity. Specifically, only 92.7% of U.S. kindergarteners were vaccinated during the 2023–2024 school year, down from 95.2% in 2019–2020. In Gaines County, Texas, the epicenter of the outbreak, only 82% of kindergarteners were up-to-date with MMR vaccines.

The outbreak has spread beyond Texas, affecting neighboring states such as New Mexico and Oklahoma, and has now reached 40 states nationwide. Iowa, for instance, reported its seventh measles case by mid-July 2025, contributing to the growing multistate outbreak. Similarly, Pennsylvania experienced a significant increase, with 15 confirmed cases by mid-2025, nearly quadrupling the four cases reported in 2024.

Health officials attribute the rapid spread to declining vaccination rates, fueled by vaccine hesitancy and misinformation. The CDC emphasizes that the MMR vaccine remains the most effective protection against measles, with two doses providing 97% protection. Despite this, vaccination rates among children have dropped since the COVID-19 pandemic, with most states falling below the 95% threshold considered effective to prevent community outbreaks.

The current outbreak underscores the importance of maintaining high vaccination coverage to prevent the resurgence of diseases once considered eliminated. The CDC and state health departments are urging the public to ensure vaccinations are up to date to prevent further transmission. In response to the outbreak, some states have tightened requirements for nonmedical exemptions to school vaccine mandates, aiming to increase vaccination rates and restore herd immunity.

The resurgence of measles highlights the broader implications of declining trust in public health initiatives and the spread of misinformation. Communities with low vaccination rates are particularly vulnerable, leading to preventable illnesses and deaths. The outbreak also places a strain on healthcare resources, with increased hospitalizations and the need for public health interventions.

The 2025 measles outbreak serves as a stark reminder of the consequences of declining vaccination rates and the spread of misinformation. Rebuilding public trust in vaccines and strengthening immunization programs are essential to prevent future outbreaks and protect public health.