Measles in the U.S., January–April 2025: 800 Cases, Three Deaths, and an Outbreak That Began in Gaines County, Texas

Measles is the most contagious fever-and-rash illness there is, infecting up to 90% of susceptible close contacts, and it can cause pneumonia, encephalitis and death. Of 4,056 U.S. cases in 2001–2022, 727 (18%) were hospitalized and three people died; of those hospitalized, 65% were unvaccinated and 26% of unknown status. Worldwide, measles vaccination is estimated to have saved 93.7 million lives between 1974 and 2024.

The United States declared endemic measles eliminated in 2000, after moving from one to two doses of measles, mumps and rubella (MMR) vaccine in 1989. But measles resurged globally when COVID-19 disrupted vaccination, raising the risk that travelers bring it home; and falling vaccination among school-age children, on top of communities that were already under-vaccinated, threatens a comeback. Large U.S. outbreaks — 50 or more cases — have become more frequent.

The first 16 weeks of 2025

From January 1 to April 17, 2025:

Confirmed measles cases by state, January 1–April 17, 2025 (800 in all). CDC

Vaccination status

771 (96%) patients were unvaccinated or of unknown vaccination status; 10 (1%) had one MMR dose and 19 (2%) two. Texas's registry requires people to opt in, so there unvaccinated and unknown can't be separated. Leaving out Texas's 590 cases, of the remaining 210:

The virus

557 (70%) cases were laboratory-confirmed. All 251 sequenced were wild-type virus: 225 (90%) genotype D8 and 26 (10%) genotype B3.

Imported cases

48 (6%) cases were imported, 44 (92%) of them in U.S. residents returning from abroad; the other 752 (94%) were acquired in the U.S. 15 (31%) importations led to further cases.

• Vaccination: 33 imported patients (69%) were unvaccinated — every one of them old enough to have been vaccinated under national recommendations, including 10 infants aged 6–11 months — one had one dose, four had two, and 10 were unknown.
• Where from: Canada (10), Vietnam (10), Mexico (7), Pakistan (3), the Philippines (2), Saudi Arabia (2), and one each from Afghanistan, Australia, Guinea, the Netherlands, Somalia, Spain and Uganda. Seven travelers had been to several countries, so the source couldn't be pinned down. They came from all six WHO regions.

Isolation, quarantine and high local vaccination kept most of these travelers from spreading the disease further.

Confirmed measles cases by week of rash onset and importation status, January 1–April 17, 2025. CDC

The outbreaks

Ten outbreaks (three or more linked cases) accounted for 751 (94%) of cases, in 12 states: Georgia, Indiana, Kansas, Kentucky, Michigan, New Jersey, New Mexico, Ohio, Oklahoma, Pennsylvania, Tennessee and Texas. Seven had an imported source; three are unexplained.

The big one began in January in a close-knit community with low vaccination coverage in Gaines County, Texas. By April 17 it accounted for 654 (82%) of the year's cases:

Its source is unknown. Another 37 cases in Kansas are suspected to be linked. It is the second-largest U.S. outbreak since elimination in 2000. An expanding outbreak in Chihuahua, Mexico, began in late February after a Mexican resident was infected, reportedly after traveling to Gaines County. Of 208 genotyped specimens from Kansas, New Mexico and Texas, all were D8; 196 (94%) had identical sequences and 12 differed by one nucleotide — expected in a long outbreak.

Why these communities

From 2001 to 2023, about 90% of U.S. outbreaks of 50 or more cases happened in close-knit communities with low vaccination coverage. Such communities may gather often and may be wary of public health and health care systems for testing, treatment and vaccination. The United States, Canada and Mexico are all seeing large, growing outbreaks in similar, interconnected communities, and travel between them across states and borders can spread measles fast.

Nationally, the risk of widespread transmission is still low, thanks to high immunity. But rising measles abroad, MMR coverage below 95% — roughly the level needed to prevent outbreaks — in many U.S. jurisdictions, and spread from domestic outbreaks have raised the risk.

What to do

Everyone:

• Before international travel, everyone 12 months or older should have documented two doses of MMR; infants 6–11 months should get one.
• In or traveling to an outbreak area, follow local public health guidance.
• Babies under 6 months are at high risk but too young to vaccinate; they rely on the immunity of those around them and on antibodies from their mothers.

Clinicians should think of measles in anyone — especially unvaccinated people — with fever of 101°F (38.3°C) or more and a generalized maculopapular rash plus cough, runny nose or conjunctivitis; recent travel abroad or to a U.S. outbreak area; or other possible exposure. Alert public health, test, and isolate. There is no FDA-approved antiviral, but prompt supportive care helps with symptoms and complications such as pneumonia and secondary infections. Offer vaccination to eligible patients without evidence of immunity.

Health departments can:

• use CDC's readiness checklist — lab testing, data reporting, tabletop exercises, early engagement with low-coverage communities;
• find at-risk communities using immunization registry data and kindergarten vaccination and exemption records;
• partner with trusted messengers, such as clinicians and religious leaders, on culturally competent engagement, education and vaccination — because standard measures like isolation, quarantine and post-exposure prophylaxis (MMR within 72 hours or immunoglobulin within 6 days) can be hard to carry out in some communities;
• coordinate with health care facilities, schools, early childhood programs and other group settings.

Above all, raising MMR vaccination coverage nationally and locally is essential.

Limits

Imports are likely undercounted — 30% of outbreaks had no known source; outbreak cases are likely undercounted, as some people in affected communities don't engage with health care; Texas data can't separate unvaccinated from unknown; and the Kansas cases couldn't be definitively linked to the large outbreak.

Sources

Based on Mathis AD, Raines K, Filardo TD, et al., "Measles Update — United States, January 1–April 17, 2025," MMWR volume 74, number 14, Centers for Disease Control and Prevention, with authors from CDC, the Texas Department of State Health Services and the New Mexico Department of Health; a work of the United States government in the public domain.