The United States is at high risk of losing its measles elimination status in November as rising case counts and sustained transmission undermine one of the country’s major public health achievements, according to a letter published late last week in The Lancet.
Measles was declared eliminated in the United States in 2000, meaning there was no continuous transmission for at least 12 months. The milestone was achieved following years of nationwide vaccination efforts, including the adoption of a two-dose measles, mumps, and rubella (MMR) immunization schedule.
The current resurgence threatens that status. With 2,288 confirmed cases in 2025 and 1,814 confirmed cases as of last week, the country is experiencing its largest measles outbreak in decades.
The decision will be made by the Pan American Health Organization Measles and Rubella Elimination Regional Monitoring and Re-Verification Commission in November.
24 new outbreaks in 2026
The epidemic, which began in Texas in early 2025 with two imported cases, has since spread to 45 states. To date, there have been 24 new outbreaks in 2026, and 93% of cases have been outbreak-associated.
This week, Utah reported 13 new measles cases, for a total of 441 cases in the state in 2026, and Colorado has confirmed 20 measles cases this year, three of them new. Most of the Colorado cases have occurred in children aged 5 to 17 years, and 19 of the 20 cases involved people who were not vaccinated.
One confirmed case was reported yesterday in Manhattan. The New York City Health Department is working to identify and notify people who may have been exposed at a restaurant.
US no longer meeting elimination benchmarks
To assess current measles transmission status in the United States, the authors of the letter used elimination indicators established by the Centers for Disease Control and Prevention in 2000, including incidence rate, transmission levels, and population immunity.
Then they used case counts reported by state health departments from January 2025 to February 2026 to calculate the effective reproduction number, which estimates the average number of infections caused by each case.
Their findings suggest that the country has already failed to meet four of seven key indicators and is unlikely to meet the remaining three. For example, current case rates far exceed elimination thresholds.
Instead of fewer than one case per 10 million people annually, which is the elimination indicator for incidence rate, the United States reported more than 90 cases per 10 million in early 2026. Another elimination indicator is a high proportion of imported cases, but most current infections are linked to local transmission rather than importation. Current outbreaks are also larger and more frequent than would be expected under elimination conditions.
Transmission rates also remain high. On 285 out of 376 days studied since January, the estimated transmission rate stayed above 1, meaning that each infected person was likely infecting at least one other person. “This estimate suggests that transmission was likely ongoing in the USA for the majority of the previous year,” write the authors.
Falling vaccination rates a key driver
Declining vaccination coverage appears to be a key factor in the measles resurgence. Coverage among kindergarteners in the 2024–25 school year was below the 95% needed to maintain herd immunity against measles.
The situation mirrors a broader global trend. Canada lost its measles elimination status in late 2025, and several European countries, including Spain and the United Kingdom, have lost their status amid rising case counts.
Given the current epidemiological context, it appears highly likely that the USA will lose its measles elimination status in 2026.
While the current analysis relies on older elimination criteria (the upcoming status review might use updated measures), the much larger number of cases in 2025 and 2026 than in 2011 suggests that the country’s elimination status is in jeopardy.
“Given the current epidemiological context, it appears highly likely that the USA will lose its measles elimination status in 2026,” the authors write. “Strengthening vaccination efforts, reducing exemption rates, and interrupting ongoing local transmission will be essential to reverse this trajectory.”
