North America is experiencing a significant resurgence of measles, leading to Canada losing its elimination status and placing the United States' long-held status under review. In 2025, the U.S. recorded its highest number of measles cases since the early 1990s, with outbreaks reported in multiple states and vaccination rates among kindergarteners declining below public health thresholds. Health officials are working to contain widespread transmission, manage complex contact tracing efforts, and clarify epidemiological links between various outbreaks as international health authorities prepare to assess the U.S. elimination designation.
North America Faces Measles Resurgence
The Pan American Health Organization (PAHO) announced in November that Canada lost its measles elimination status, a designation it had held for nearly three decades. This decision followed Canada's inability to contain a measles outbreak for 12 consecutive months, with over 5,000 cases reported in 2025, primarily in Ontario and Alberta. Consequently, the Americas region, which first achieved measles elimination in 2016 and regained it in 2024 after temporary revocation, has also seen its overall status impacted, although most individual countries retain their certification.
The United States is also confronting a substantial increase in measles cases, with its elimination status, maintained since 2000, under evaluation. In 2025, the U.S. reported 2,144 confirmed measles cases across 44 states, marking the highest annual total since 1992. Early 2026 saw 171 cases reported in the first two weeks across nine states, approaching the average annual total recorded since the disease was declared eliminated.
Key Outbreaks Across U.S. States
Multiple states have experienced large and ongoing measles outbreaks:
- South Carolina: An outbreak, primarily concentrated in Spartanburg County, began in early October. Case numbers escalated from approximately 180 in December 2025 to 558 by late January 2026. Health officials reported that 172 out of an initial 185 cases involved unvaccinated individuals. Hundreds of people have been placed in quarantine, with public exposures identified in churches, restaurants, shops, schools, and healthcare settings. State epidemiologist Dr. Linda Bell noted the challenge in tracking all cases due to widespread transmission.
- Texas: A major outbreak commenced in West Texas in January 2025 and concluded in mid-August. This outbreak affected 762 individuals, predominantly in rural Gaines County, and resulted in the deaths of two unvaccinated children. An additional 182 potential cases in Gaines County went unconfirmed.
- Utah-Arizona Border: This outbreak began in June 2025, with over 350 cases reported across both states in 2025 and more than 200 cases in Utah by early 2026, primarily in the southwest region. While some officials indicated the Utah strain appeared distinct from the Texas outbreak, other reports suggested a link between the Utah and Texas strains.
- North Carolina: In January 2026, three siblings in Buncombe County and a child in Polk County were confirmed with measles after visiting Spartanburg County, South Carolina. Potential public exposure sites were identified in Asheville. Earlier, in June 2025, North Carolina reported its first case of the year in an international traveler.
- Oregon: The state confirmed its first two measles cases of 2026 in Linn County on January 10, followed by a third case in Clackamas County on January 12. Public exposure sites were identified at emergency departments in Lebanon and Albany. Oregon’s first 2025 case involved an international traveler in June.
- Other States: New Mexico reported 100 cases and one adult fatality in 2025, with a warning issued regarding potential exposures from a traveler who visited South Carolina. Washington State declared an outbreak in Snohomish County with three cases. Georgia, Ohio, Montana, North Dakota, Virginia, Wisconsin, and Florida have also reported cases or outbreaks.
Vaccination Trends and Public Health Response
National data from the U.S. Centers for Disease Control and Prevention (CDC) indicates a decline in MMR (measles, mumps, and rubella) vaccination rates among kindergarteners. For the 2024-2025 school year, 92.5% of incoming kindergarteners had received the MMR vaccine, a decrease from 92.7% in the previous school year and 95.2% in the 2019-2020 school year. This rate falls below the 95% threshold considered necessary for herd immunity.
Factors contributing to lower vaccination rates include:
- Increased nonmedical vaccine exemptions, with religious exemptions nearly doubling in South Carolina since the COVID-19 pandemic.
- Limited access to general practitioners.
- Absence of a national vaccination registry.
- Dissemination of misinformation.
- Insufficient public health outreach to vaccine-hesitant communities.
Public health departments are implementing various containment strategies, including contact tracing, issuing public exposure notifications, organizing pop-up vaccination clinics, and advising unvaccinated exposed individuals to quarantine for 21 days. The resource-intensive nature of these efforts, coupled with widespread transmission, presents challenges in tracking all cases and links.
The Disease and the Vaccine
Measles is a highly contagious, vaccine-preventable disease transmitted through airborne particles. Symptoms typically appear 7 to 21 days after exposure and include high fever, cough, runny nose, red watery eyes, tiny white spots (Koplik Spots) inside the mouth, and a red, blotchy rash. Individuals are contagious from four days before the rash appears until four days afterward.
Complications can be severe, including pneumonia, ear infections, brain swelling (encephalitis), hearing or vision loss, and in rare cases, death (1 to 3 out of every 1,000 children). The virus can also cause "immune amnesia," compromising previously acquired immunity.
The MMR vaccine provides robust protection:
- One dose is 93% effective against measles.
- Two doses are 97% effective, offering lifelong immunity.
- The first dose is typically recommended between 12 and 15 months of age, with the second between ages 4 and 6. During outbreaks, the first dose can be administered as early as 6 months.
- For unvaccinated individuals exposed to the virus, an MMR vaccine administered within 72 hours may offer some protection or lead to milder illness.
Challenges in Tracking and International Review
The U.S. measles elimination status is being reviewed by PAHO in April. To retain the status, the U.S. must demonstrate that no locally transmitted cases of the same measles strain have continuously spread for 12 months or longer. Establishing definitive epidemiological links between outbreaks, such as those in Texas and South Carolina, has been challenging due to data gaps, particularly in communities distrustful of public health systems, and the limited utility of genetic sequencing for the slowly mutating measles virus.
The CDC's initial, unpublished analyses suggested no epidemiological link between the Texas outbreak and ongoing cases in South Carolina. However, the presence of the same measles strain in multiple locations, including Texas, New Mexico, Utah, Arizona, South Carolina, Canada, and Mexico, complicates the assessment. Mexico's measles-free status will also be reviewed following an outbreak that has sickened 6,000 people and caused 21 deaths in Chihuahua state.
Public and Political Engagement
Public figures have engaged in discussions surrounding vaccine use. In 2025, Robert F. Kennedy Jr., then Secretary of Health and Human Services, encouraged measles vaccination, describing MMR vaccines as "crucial" for prevention. However, he also made claims regarding the MMR vaccine containing "aborted fetus debris and DNA particles" and linking vaccination to autism, claims that have been characterized as false and disputed by the medical community. U.S. Senators Ron Wyden and Jeff Merkley of Oregon requested Secretary Kennedy to take action to limit measles transmission. In South Carolina, pediatrician Annie Andrews, a Democratic candidate, has incorporated combating the measles outbreak into her campaign.