A peer-reviewed study published in The Lancet on April 30, 2026 is sounding a formal alarm: the United States is on track to lose its measles elimination status — a designation it has held since the year 2000. Researchers from Boston Children’s Hospital found that the country has already missed four of the seven CDC benchmarks required to maintain that status, with the remaining three at serious risk.
The findings arrive at a critical moment. The latest string of U.S. outbreaks began in Texas in January 2025. Since then, outbreaks have spread to 45 states, with the U.S. now recording approximately 93 cases per 10 million people — far exceeding the CDC’s elimination threshold of less than one case per 10 million.
What Measles Elimination Actually Means
Measles elimination does not mean the virus has been eradicated. It means the virus is no longer spreading continuously within a country for more than 12 consecutive months. The United States achieved that status in 2000, ending decades of widespread domestic transmission through a sustained national vaccination effort.
After public health experts declared measles eliminated in 2000, the CDC established seven indicators of measles elimination status to ensure that the country remained on track. Researchers from Boston Children’s Hospital, led by Dr. Maimuna Majumder and postdoctoral fellow Dr. Anne Bischops, evaluated the number of U.S. measles cases, outbreaks, their origination, and levels of transmission against these same indicators.
The study found that four indicators are now in the red, with the remaining three at risk — indicating that measles could once again become a part of day-to-day life in America.
The United States experienced its worst year for measles in over three decades in 2025, with 2,144 confirmed cases. According to the CDC, there were 49 outbreaks that year, and 88% of confirmed cases were outbreak-associated.
In the first three months of 2026 alone, the U.S. logged 1,671 measles cases — 73% of the entire 2025 total. The pace shows no sign of slowing.
A higher percentage of cases since 2025 have been due to local transmission rather than importation compared to prior years, indicating that local spread has become the primary source of reported cases. That shift is significant: imported cases signal an occasional breach at the border, while local transmission means the virus is circulating on its own within U.S. communities.
The Vaccination Gap Driving the Outbreak
The data points consistently to one central cause: falling vaccination rates. Vaccination coverage of the measles, mumps, and rubella (MMR) shot in children declined from 95.2% during the 2019–2020 school year to 92.5% during the 2024–2025 school year. About 92% of cases so far this year were in people who were unvaccinated or whose vaccination status was unknown.
Over three-quarters of states had MMR vaccination rates below the 95% target in the latest available data. Additional studies found that 78% of U.S. counties reported a decline in two-dose measles vaccine coverage in children, with the average county-level rate falling from 93.9% in 2019 to 91.3% in 2024.
The 95% threshold matters because it is the level generally required for herd immunity — the point at which enough of the population is protected that even unvaccinated individuals are shielded by the reduced spread of the virus. According to a report from the Common Health Coalition, just a 1% decrease in the childhood MMR vaccination rate could cause 17,000 measles cases, 4,000 hospitalizations, and 36 preventable deaths each year.
Non-medical exemptions have also risen. In South Carolina — the epicenter of one of the country’s largest current outbreaks — religious exemptions have more than doubled since 2020, with 4% of school-age students holding such exemptions in the 2025–26 school year.
Who Is Most at Risk
Infants too young to receive the vaccine represent one of the most vulnerable groups. The MMR vaccine is typically administered at 12 to 15 months of age, leaving babies in their first year entirely dependent on herd immunity for protection.
Dr. Majumder noted that measles infections, even when cleared, can result in lifelong problems. Babies less than a year old are among those at the highest risk for severe complications, and the full impact on children exposed during the current outbreak may not become apparent for years.
What Happens Next
The Pan American Health Organization’s expert panel is scheduled to reevaluate the United States’ measles elimination status at its November 2026 meeting. The Boston Children’s Hospital study was published specifically to provide an evidence base ahead of that review.
The U.S. would not be the first high-income country in the Americas to cross this line. Canada lost its measles elimination status on November 10, 2025, following a large outbreak in 2024 and more than one year of sustained transmission of the same measles virus strain within the country.
Researchers stated that strengthening vaccination efforts, reducing exemption rates, and interrupting ongoing local transmission will be essential to reverse the current trajectory. Without a measurable shift in vaccination coverage and public health response, the November review is expected to formally confirm what the data already shows.
Disclaimer: This article is intended for informational and public awareness purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. For guidance on vaccination schedules and personal health decisions, consult a qualified healthcare provider or visit the CDC at cdc.gov.
