U.S. May Lose Measles Elimination Status

The United States could be on the verge of losing its status of measles elimination as early as January, signifying a concerning return of a disease that the nation had successfully eradicated 25 years ago.

On November 10, Canada recently lost its own measles elimination status, following a conclusion by the Pan American Health Organization. They determined that the recent outbreaks in Canada were interconnected and demonstrated ongoing transmission for over a year. It’s worth noting that a disease is considered eliminated in a region only when there are no outbreaks persisting for more than a year. Basically, to keep that elimination status intact, any new cases need to be contained within 12 months of travel-related introductions.

A significant outbreak in West Texas, which began in January 2025, has apparently ended. But, while it was ongoing, it may have ignited cases in Arizona and Utah, where outbreaks still persist. If public health officials find enough proof linking these cases, it’s likely that by January 2026, the U.S. could lose its elimination status.

“We’re not entirely sure how the situation will be evaluated in January,” mentioned Dr. Diego Hijano, an infectious disease specialist at St. Jude Children’s Research Hospital. “However, given the cases originating in Texas that have continued to spread, there’s a high likelihood they may determine there have been 12 months of ongoing cases from that area.”

Measles elimination is a vital goal for public health due to the disease’s severe symptoms, which include high fever and a distinctive red rash. While initially very uncomfortable, measles can lead to serious complications, such as pneumonia and swelling of the brain. According to the Centers for Disease Control and Prevention (CDC), the mortality rate for children who contract measles is significant, ranging from 1 to 3 deaths per 1,000 cases during this acute phase.

For those who survive, measles can lead to long-lasting health issues. This can include a phenomenon known as immune “amnesia,” which leaves survivors more vulnerable to other illnesses. Additionally, around 7 to 11 out of every 100,000 infected individuals risk a fatal complication years after their initial infection called subacute sclerosing panencephalitis, a progressive neurological disorder.

Receiving two doses of the measles, mumps, and rubella (MMR) vaccine lowers the chance of contracting measles by 97%. However, measles is exceedingly contagious, meaning that to eliminate it, vaccination rates need to be quite high. In a non-immune population, one measles case can potentially infect between 12 and 18 others. To effectively control an outbreak, this number must be reduced to less than one, which requires about 95% of the population to be immune either through vaccination or previous infection, as Dr. Hijano pointed out.

Currently, about 92.5% of kindergartners are up to date on their MMR vaccinations, according to recent CDC data from the 2024-2025 school year. This figure seems to be even lower in specific communities, like a predominantly Mennonite area in West Texas. These pockets of low vaccination rates not only put individuals at risk but also complicate the task of public health officials trying to manage and contain potential outbreaks, noted Amy Winter, a demographer and infectious disease researcher at the University of Georgia.

“It’s just so much more challenging for personnel to carry out case investigations,” Winter remarked. Given that many people in these communities are unvaccinated, health officials may find it difficult to trace contacts of infected individuals and advise them on isolating or getting a post-exposure vaccine, which could mitigate or lessen the severity of a measles infection.

“Failing to halt transmission within 12 months,” Winter said, “indicates that we truly don’t have command over this pathogen.”

In 2025, the U.S. has recorded 45 measles outbreaks and 1,723 confirmed cases, according to CDC data available as of November 12. To explore whether these outbreaks are related and indicative of ongoing transmission, health officials investigate each case, looking at the overlap of times and places where infected individuals may have interacted with others.

Genetic testing is also performed to determine if the strains of measles causing the cases are connected or if the outbreak stems from separate introductions. Most cases linked to travel occur when a susceptible person returns from areas where measles is endemic.

Recent discussions among public health officials have indicated that the West Texas outbreaks are tied to the ongoing situations in Utah and Arizona. If these connections are confirmed, the U.S. could lose its elimination status in January unless those outbreaks are contained without further spread.

Out of the verified U.S. cases this year, 92% involved unvaccinated individuals, and around 4% involved people who had only received their first MMR dose. The recommended vaccination schedule recommends the first dose at age one and a second dose between ages four and six. Dr. Hijano emphasized that to control measles effectively, the nation’s vaccination rate needs to exceed 95%.

“As long as we can’t achieve that high rate of immunization,” he concluded, “we’ll always have cases of measles entering the country from elsewhere and finding opportunities to spread.”