U.S. Measles Outbreak Reaches 800 Cases, Marking Largest Since Disease Elimination in 2000
Key Insights
The United States is experiencing its largest measles (search) outbreak since the disease was declared eliminated in 2000, with at least 800 confirmed cases nationwide and likely more unreported.
Texas has been hit hardest with 624 cases since January, resulting in two pediatric deaths—the first U.S. measles (search) fatalities in a decade—with 85 hospitalizations nationwide representing approximately 11% of cases.
The outbreak disproportionately affects unvaccinated populations, particularly Mennonite communities, and has spread across North American borders with nearly 1,000 cases in Ontario, Canada and over 400 in Chihuahua, Mexico.
The United States is currently facing its most severe measles (search) outbreak in over two decades, with federal health officials confirming at least 800 cases nationwide since the beginning of 2025. This marks the largest outbreak since measles was declared eliminated in the country in 2000, according to the Centers for Disease Control and Prevention (search) (CDC (search)).
The outbreak has been particularly devastating in Texas, which alone has reported 624 cases since late January, according to the Texas Department of State Health Services (search). Oklahoma and New Mexico are also experiencing significant case numbers, with the disease now confirmed in at least 12 states across the country.
"This is the largest outbreak in the U.S. since measles (search) elimination was declared in 2000," said Dr. Dan Filardo, who leads the CDC (search)'s measles task force. In response, the CDC is deploying additional staff to Texas to help manage the escalating situation.
Tragic Outcomes and Hospitalization Rates
The outbreak has resulted in two confirmed pediatric deaths in Texas, both unvaccinated children, representing the first measles (search) fatalities in the United States in a decade. Approximately 11% of those infected—85 individuals—have required hospitalization.
Children have been disproportionately affected, with about 70% of cases occurring among pediatric populations. The median age of those infected is 8 years old. Health officials note that the majority of cases have been among unvaccinated individuals, though the vaccination status of some patients remains unknown.
Dr. David Sugerman, a senior scientist at the CDC (search), told NBC News that the actual number of cases is likely higher than reported. "We do believe that there's quite a large amount of cases that are not reported and underreported," Sugerman explained. "In working very closely with our colleagues in Texas and in talking with families, they may mention prior cases that have recovered and never received testing or other families that may have cases and never sought treatment."
Cross-Border Transmission and Community Impact
The outbreak has transcended national boundaries, with nearly 1,000 cases reported in Ontario, Canada, and more than 400 cases in Chihuahua, Mexico. Mennonite communities, which typically have lower vaccination rates, have been particularly hard-hit.
"With ongoing weddings, large religious gatherings and celebrations to mark the 500th anniversary of Mennonite origins, we remain concerned about the possibility of additional spread of measles (search) across North American Plains communities as the year goes on," Filardo warned.
If the current trajectory continues, this outbreak could surpass the 2019 total of 1,249 cases, which required an 11-month response involving hundreds of public health workers and more than $8 million in expenditure.
Challenges in Response Efforts
The public health response has been hampered by budget constraints and staffing shortages. "We're scraping to find the resources to support states affected by the outbreaks," Sugerman acknowledged.
Further complicating matters are mixed messages from health officials. Robert F. Kennedy Jr., head of the U.S. Department of Health and Human Services (search), has reportedly downplayed vaccines while promoting alternative treatments like cod liver oil. In Texas, physicians report that some patients are delaying evidence-based medical care in favor of supplements endorsed by Kennedy.
Understanding Measles Transmission and Prevention
Measles (search) is considered one of the most contagious viruses known to science. A single infected individual can transmit the virus to as many as 18 others through respiratory droplets. These viral particles remain viable in the air and on surfaces for up to two hours after being expelled.
The measles (search), mumps, and rubella (MMR) vaccine remains the most effective prevention tool. The first dose is 93% effective at preventing infection, while the second dose increases efficacy to 97%. These doses are typically administered at 12-15 months and 4-6 years of age, respectively.
Despite its proven safety and effectiveness, vaccine hesitancy continues to pose a significant challenge to public health efforts. Much of this hesitancy stems from a now-thoroughly debunked 1998 study that falsely linked the MMR vaccine to autism. Although the study was retracted, its damaging effects on public perception have persisted and were exacerbated by broader vaccine skepticism during the COVID-19 pandemic.
Ongoing Prevention and Response Measures
Health departments in affected areas have launched mobile vaccination clinics, school-based immunization programs, and targeted outreach to vulnerable populations. The CDC (search) has enhanced surveillance efforts, expanded testing access, and provided updated guidance to healthcare providers on recognizing and reporting measles (search) cases promptly.
International coordination is also underway, with health officials in Canada and Mexico working alongside the CDC (search) to monitor cross-border transmission and align public messaging. The World Health Organization has expressed concern about the global implications of measles (search) resurgence and is urging countries to strengthen routine immunization programs.
"Vaccination remains the best tool to prevent and respond to measles (search) outbreaks," Filardo emphasized, echoing the consensus among public health experts worldwide.
As the outbreak continues to evolve, health officials are urging parents to ensure their children are up-to-date on vaccinations and to seek immediate medical attention if symptoms of measles (search)—including high fever, cough, runny nose, and a characteristic rash—develop.