Measles Outbreak — New Mexico, 2025

Abstract

Measles is a highly contagious respiratory virus with the potential to cause large outbreaks, as well as serious complications, hospitalization, and death. Receipt of 2 doses of measles vaccine is 97% effective at preventing disease and is recommended for all persons aged ≥12 months to ensure high levels of population immunity and reduce the risk for outbreaks. In January 2025, a large measles outbreak began in a west Texas community and quickly spread to nearby jurisdictions, including New Mexico. The New Mexico Department of Health (NMDOH) eventually reported 99 outbreak-related measles cases, approximately one half of which occurred in adults. To facilitate dissemination of information and distribution of resources across a geographically large, rural state, NMDOH implemented a multimodal communication and vaccination outreach strategy, including a centralized webpage, a telephone helpline, and mobile vaccination clinics. The outreach strategy coincided with a statewide 55% increase in MMR vaccine doses administered during January 1–September 26, 2025, compared with the same period in 2024. Coordinating public communication and improving access to MMR vaccine can support vaccine administration across large, rural areas and contribute to a measles outbreak response.

Introduction

Measles (rubeola) is a highly contagious respiratory virus that has the potential to cause large outbreaks, as well as serious complications, hospitalization, and death; measles was declared eliminated from the United States in 2000. Symptoms of measles include fever, malaise, cough, coryza, and conjunctivitis, as well as a pathognomonic enanthem (Koplik spots) followed by a maculopapular rash. The incubation period is typically 11–12 days (range = 7–21 days) from exposure to measles virus until the first symptoms appear (1). Two doses of measles, mumps, and rubella (MMR) vaccine are estimated to be 97% effective at preventing measles (2). In 2025, the United States experienced the largest number of measles cases and outbreaks since 1992, including the first outbreak in New Mexico since 1996. Among 99 confirmed measles cases in New Mexico, 14 (14%) patients had documentation of receipt of ≥1 dose of a measles vaccine. The New Mexico Department of Health (NMDOH) implemented a multimodal communication and vaccination response to reduce transmission. This report describes the response to the New Mexico outbreak.

Investigation and Outcomes

Notification of Confirmed Measles Cases in Texas

On January 30, 2025, NMDOH was notified by the Texas Department of State Health Services of two confirmed measles cases in Gaines County, Texas. Gaines County, located in west Texas, is bordered on the west by Lea County, New Mexico, and is an area where frequent bidirectional travel occurs across the state line. NMDOH distributed a first statewide Health Alert Network (HAN) message on January 31, and a first press release on February 3 regarding the increased risk for exposure to measles in Lea County.

Notification of First Measles Cases in New Mexico

On February 9, 2025, NMDOH was notified of a suspected case of measles in an unvaccinated school-aged child in Lea County. The child had not recently travelled outside New Mexico and had no known exposure to close contacts with measles. A nasopharyngeal swab collected for real-time reverse transcription–polymerase chain reaction measles testing at the Scientific Laboratory Division (SLD), New Mexico’s public health laboratory, was confirmed positive for measles on February 11. Later that week, two Lea County adults whose measles vaccination history was unknown also received positive measles test results at SLD. Although one patient had visited Texas during the 3 weeks preceding illness onset (i.e., during the patient’s incubation period), apart from living in Lea County, none of the three patients had a known connection with one another. NMDOH declared a measles outbreak on February 14 and began an investigation. This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.*

Characteristics of Outbreak-Related Measles Cases

During February 9–August 10, 2025, a total of 99 outbreak-related measles cases^† were reported from eight New Mexico counties; two thirds (67.7%) of patients lived in Lea County.^§ Sixteen (16.2%) persons with measles, including 20.9% of cases in Lea County residents, reported travel to Texas during their incubation period. The median patient age was 20 years (range = 4 months–62 years), and most (85.8%) cases occurred in persons who were unvaccinated (57.6%) or whose vaccination status was unknown (28.3%) (Table). No school or child care center outbreaks were reported. Seven patients with measles were confirmed to have been hospitalized, including five unvaccinated children, one unvaccinated adult, and one adult whose vaccination history was unknown; the median length of hospitalization was 1 day (range = 1–5 days). One death attributed to measles was reported in an unvaccinated adult. The New Mexico outbreak was declared over on September 26, 2025, after two 21-day measles incubation periods had elapsed since the last reported patient’s infectious period ended on August 14.

Public Health Response

Communication Activities and Coordination Strategies

To facilitate distribution of information and resources across the large, rural state of New Mexico, NMDOH implemented a multimodal communication strategy. Outbreak information and vaccination recommendations were distributed via 12 HAN advisories, 26 press releases, 184 social media posts, the New Mexico Statewide Immunization Information System (NMSIIS) newsfeed and email notifications, television public service announcements, and local radio (3). On February 21, NMDOH launched a measles webpage, which included regularly updated case counts; guidance for vaccination, preparedness, and response to measles exposures in various settings and populations (e.g., health care settings, workplaces, and schools); and information about upcoming vaccination clinics (4). Messaging in English and Spanish referred members of the public to the NMDOH helpline number, which was established during the COVID-19 pandemic to connect New Mexicans with health information and services. Helpline staff members could check callers’ measles vaccination status in New Mexico by using NMSIIS, notify contacts about their exposure to persons with measles, and assist in identifying nearby locations where vaccines could be administered. The helpline received 2,004 measles-related calls during January 31–August 24, 2025.

Vaccination Clinics and MMR Vaccine Doses Administered

Providers participating in the Vaccines for Children Program and Section 317 Immunization Program for adults^¶ could order MMR vaccine for immediate administration at no cost and without waiting for the usual scheduled monthly order. NMSIIS was used to assess local vaccination coverage data and vaccine inventory, prioritizing areas for mobile vaccine delivery, including those areas with identified cases of measles or below-average MMR vaccination coverage. On April 14, 2025, NMDOH recommended early vaccination for infants aged 6–11 months who lived in or had visited areas with an increased risk for exposure to measles.**

During February 15–August 24, NMDOH hosted 60 mobile MMR vaccination clinics in 11 counties. These were located mainly at schools, public health offices, correctional facilities, and community centers or events and were conducted in collaboration with local partners. The clinics were initially held in counties with reported cases (and surrounding areas), but communities with no reported cases could also request mobile clinics as a preventive measure. At the start of the outbreak, statewide coverage with ≥1 dose of MMR vaccine was 92% among children and 51% among adults (NMSIIS data). Additional vaccination outreach and communications coincided with a 55% increase in MMR doses administered during January 1–September 26 (61,592) compared with the same period in 2024 (39,847) (Figure). From February 14, when the measles outbreak was declared, through September 26, first and second MMR doses were received by 15,123 and 16,622 children, respectively, and 16,164 and 3,711 adults, respectively. Compared with 2024, the number of doses administered to children aged <18 years increased 18%, from 27,988 in 2024 to 32,890 in 2025; doses administered to adults aged ≥18 years increased 291%, from 5,748 in 2024 to 22,500 in 2025. Within 2 weeks of the outbreak declaration, the number of vaccine doses administered in all regions of the state began to exceed the number delivered during the previous year. Region-specific increases in vaccine doses administered also occurred during the week after the first cases in a given region were announced compared with the preceding week (e.g., 82.7% and 77.7% increases in the Southwest and metropolitan public health regions, respectively). As of September 26, 2025, single-dose MMR vaccination coverage among Lea County residents aged 1–18 years had increased from 94.0% to 95.1%. However, because Lea County accounts for approximately 3% of the state population, statewide coverage among children and adults did not change significantly.

Discussion

This measles outbreak was the first in New Mexico since 1996 (5). Most outbreak-related cases occurred among persons who were unvaccinated or whose vaccination status was unknown. Despite known community transmission, no school outbreaks were reported from Lea County, likely because of high MMR vaccination coverage (94% coverage with ≥1 dose among persons aged 1–18 years in schools [NMSIIS data] and 96.6% coverage with 2 doses among Lea County kindergarteners [New Mexico school immunization survey, unpublished data, 2025]). The 51% documented coverage among adults statewide likely underestimates immunity among adults, because information about past measles infection or vaccinations occurring before the immunization registry’s creation is not captured in NMSIIS. However, the preponderance of measles cases reported among adults and sustained community transmission suggests that high county-level immunization coverage obscured areas of undervaccination. Increasing and maintaining high 2-dose measles vaccination coverage strengthens herd immunity and can limit community transmission and outbreak size (6). NMDOH recommends that all persons aged ≥12 months receive 2 doses of measles vaccine for best protection against measles (3).

The 2025 measles outbreak response in New Mexico benefited from coordinated operations for communication and vaccination, building on experience developed during the COVID-19 pandemic. Implementation of a range of communication strategies, including the measles webpage and the centralized telephone helpline, facilitated resident access to updated measles information and recommendations while the outbreak evolved and supported access to vaccination services, bolstering the outbreak response statewide. A comprehensive messaging strategy prompted community interest in vaccination and in protecting both children and adults from measles.

Despite challenges associated with distributing resources across the large, rural state of New Mexico, after identification and declaration of a measles outbreak in a single county, the number of MMR doses administered rapidly increased statewide. The strategies implemented in New Mexico could serve as a model for other states that are addressing measles cases or outbreaks.