The United States is poised to lose its measles eradication designation in 2026 unless public health experts are able to curb an ongoing outbreak of the infection in South Carolina and several other states.
South Carolina has been the latest state to struggle with a measles outbreak in 2025, largely due to pockets of unvaccinated communities. But public health experts warn that the disease will no longer be considered eliminated in the United States unless the spread of the virus comes to a halt within a few short weeks.
Any infectious disease can be considered eradicated in a country if it no longer spreads continuously for a full calendar year. That deadline is quickly approaching, as the first of 2025’s measles outbreaks started in a Mennonite community in western Texas on Jan. 20.
The number of recorded measles cases in the U.S. exceeded 2,000 in 2025, according to the Centers for Disease Control and Prevention. The vast majority of cases, approximately 93%, occurred in unvaccinated patients, most of whom are under age 18.
Measles cases have been reported in more than 44 CDC jurisdictions, including 43 states and New York City, with 50 reported measles outbreaks, consisting of three or more clustered cases.
That’s compared to only 16 outbreaks and only 285 confirmed measles cases in 2024 and nearly 1,300 cases in 2019.
South Carolina’s state epidemiologist, Dr. Linda Bell, said in a press briefing on Tuesday that measles transmission is continuing, with more than 287 people in quarantine to slow the spread. She said her team expects “more cases well into January.”
The surge in measles cases across the country is largely attributable to a decline in childhood vaccination rates, with less than 93% of kindergarteners receiving two doses of the combination measles, mumps, and rubella, or MMR, vaccine for the 2024-2025 school year. A vaccination rate of 95% is needed for a population to achieve herd immunity.
According to the University of Chicago Medicine, measles is not life-threatening for most people, but it is virtually impossible to predict who will become seriously ill if infected.
Three in every 1,000 people who contract measles will die, with young children and immunocompromised people most at risk. Before widespread vaccination, roughly 500 people in the U.S. each year died from the disease.
Many public health experts have expressed concern that vaccine skepticism espoused by Health and Human Services Secretary Robert F. Kennedy Jr. has contributed to U.S. measles outbreaks, but childhood MMR vaccination rates have been on a steady decline since 2019, with the rise of anti-vaccine rhetoric in the wake of the COVID-19 pandemic.
Tracking vaccination rates is one way public health officials can coordinate resources to mitigate outbreak risks; however, doing so proves challenging, as many states do not publish local-level data on vaccine uptake.
A study published in October found that Texas’s local vaccine data showed an overall MMR vaccine uptake rate of 82% in Gaines County, where the Jan. 2025 outbreak originated. However, the school-based vaccination rate ranged from 46.2% to 94.3%, indicating that low school vaccination rates in certain communities pose the greatest risk.
“With attention to school-level coverage instead of state-level coverage as the barometer for risk, we can avoid overlooking critical clusters of unvaccinated children, whose existence is demonstrated by our analysis,” the authors of the October paper wrote.
