International health authorities are preparing to evaluate whether the United States should lose its measles elimination status, a designation the country has held since 2000. The possible change stems from sustained, multi-state transmission linked to outbreaks that began in early 2025 and continued into 2026, raising concern that measles is again finding enough unvaccinated pockets to spread for long periods.
The Pan American Health Organization (PAHO) is expected to consider the U.S. situation at a meeting on April 13, 2026. Under the commonly used definition, a country can lose elimination status when there is uninterrupted measles transmission for at least 12 months. Public health leaders say the label is less important than the underlying warning: vaccination coverage and response capacity have weakened enough to allow repeated outbreaks to connect and persist.
In 2025, the U.S. recorded 2,242 confirmed measles cases across 44 states, the most since 1991, along with nearly 50 separate outbreaks. Health officials and researchers say the resurgence is being driven by a combination of factors: declining childhood vaccination rates, misinformation that fuels hesitancy, uneven access to care, and public health systems that struggle to staff and sustain the intensive contact tracing and quarantine work measles demands.
Genetic sequencing has helped investigators track how a single measles strain can appear in different places across North America, but measles mutates slowly, meaning genomic data can’t always prove which outbreaks are directly connected. That uncertainty complicates the effort to map transmission chains precisely, especially when cases and exposures occur across state and national borders.
Experts emphasize that measles is highly contagious and that the MMR vaccine remains a safe and effective way to prevent it. The current trajectory, they warn, signals more than just a measles problem: it reflects a broader vulnerability to other vaccine-preventable diseases if communities continue to fall below the coverage levels needed to protect schools and households from explosive spread.
- What’s happening: PAHO plans an April 13, 2026 review of whether the U.S. should lose measles elimination status.
- Why: ongoing transmission linked to outbreaks that began in January 2025 and continued across states.
- Context: 2,242 U.S. measles cases in 2025 and nearly 50 outbreaks, tied to declining vaccination coverage and public health strain.