Record-Breaking Measles Cases in the U.S. for 2026

Measles cases in the United States have already set a new record for 2026 with five months left in the year. The Centers for Disease Control and Prevention (CDC) reported 2,318 cases as of their latest update. This number surpasses the total from 2025 when the U.S. experienced its worst measles outbreak in over three decades with 2,289 cases.

Major outbreaks have been reported in South Carolina, Utah, and Arizona, contributing significantly to this year’s high numbers. The coming months will include a meeting of international health officials to decide if the U.S. and Mexico will lose their measles-free status, an achievement first reached in 2000 through high vaccination coverage. However, vaccination rates have recently dipped below the 95% threshold necessary to avoid outbreaks.

Undercounted Measles Cases

There is acknowledgment among public health experts that reported measles cases may not reflect the true extent of the outbreak. Some individuals contract measles but do not seek treatment, leading to an underreporting of cases.

The drop in national vaccination rates exacerbates the problem. For example, the vaccination rate among kindergartners fell to 92.5% in the 2024-2025 school year, compared to 95.2% in 2019-2020. Certain communities report even lower numbers.

Utah’s Ongoing Challenges

Utah is grappling with a persistent outbreak that has affected over 700 people. Epidemiologist Dr. Leisha Nolen notes the actual outbreak might be three to four times larger than current figures suggest, based on mathematical modeling and genetic analyses.

In South Carolina, where the largest outbreak in 35 years occurred, the state health department suspects the reported 997 cases are underestimated, but an accurate count remains elusive.

Estimating Outbreak Scale

Determining the full scale of measles outbreaks poses significant challenges. Hospitalization rates, though not universally reported, serve as one indicator of outbreak size. Applied mathematician Damon Toth emphasizes the value of a consistent severity measure across cases to better gauge outbreak magnitude.

Texas’ Past Outbreak

Researchers are still examining the size of Texas’ 2025 outbreak. Initial analyses suggest the number of cases could be nearly double the reported 762. The absence of a robust 95% community vaccination rate makes controlling measles challenging, according to epidemiologist Rémy Pasco.

Texas chief state epidemiologist Dr. Varun Shetty explains that unreported measles cases can arise due to a lack of data on household contacts during outbreaks, impeding efforts to understand the full scope of transmission.

Importance of Vaccination

Vaccination remains critical to protect both individuals and communities. Dr. Mark Roberts from the University of Pittsburgh School of Public Health highlights the risks to those who cannot be vaccinated, such as infants and immunocompromised individuals. He likens neglecting vaccination to operating a car without brakes, as it endangers others, not just the unvaccinated individual.