Measles Cases Surge in the United States
Recent federal data indicates that over 2,000 measles cases have been reported in the United States this year, marking the highest annual count seen in decades.
Ongoing outbreaks, especially in upstate South Carolina and along the Arizona-Utah border, continue to add dozens of new cases weekly. This situation poses a serious risk to the US’s measles elimination status, which has been maintained for about 25 years.
According to data from the US Centers for Disease Control and Prevention, there have been 2,065 confirmed cases of measles in the US as of December 30, 2026. The last time the annual count exceeded 2,000 cases was in 1992, shortly after health officials updated their vaccination recommendations, advising that children should receive two doses of the measles-mumps-rubella (MMR) vaccine instead of just one.
Measles is known to be extremely contagious, but the MMR vaccine provides robust protection. Specifically, one dose offers about 93% effectiveness against the virus, while two doses increase the effectiveness to 97%, as noted by the CDC.
Despite this, vaccination rates have been declining for several years. Data from the CDC shows that only 92.5% of incoming kindergarteners received the MMR vaccine last school year, falling below the essential 95% threshold needed to prevent outbreaks.
Since 2000, measles has been considered eliminated in the US, which means no outbreaks or transmission chains have persisted beyond a year. However, this year has seen several significant outbreaks that may be interconnected, endangering the elimination status if cases continue to rise into late January.
For instance, an outbreak that began in West Texas in late January was declared over in mid-August, but not before hundreds of related cases emerged across Texas and New Mexico. Unfortunately, three unvaccinated individuals—two children and one adult—lost their lives as a result.
In early October, health authorities in South Carolina confirmed a measles outbreak in the upstate region. Over the last four months, this outbreak has resulted in nearly 180 cases, with at least 20 new infections reported since Friday, causing close to 300 individuals to be quarantined due to potential exposure.
“We know that many of our cases involve people in quarantine due to known exposures,” said Dr. Linda Bell, the state epidemiologist for South Carolina. She noted that transmission is occurring within households, schools, and churches.
Another outbreak along the Utah-Arizona border is also expanding, with over 350 reported cases in total this year.
In November, the Pan American Health Organization (PAHO) determined that Canada had lost its measles elimination status amid a significant ongoing outbreak there. PAHO Director Dr. Jarbas Barbosa remarked that all other 34 countries in the region still maintain their measles-free certification.
However, possible genetic connections between the Texas outbreak and the ongoing situation in South Carolina cast doubt on the US’s status. Dr. Bell indicated, “We anticipate more cases into January. What this means for the national designation of measles elimination is still uncertain.”
