Measles has been officially “eliminated” from the U.S. since 2000, which means the country had not seen very large outbreaks and had not had 12 months or more of uncontrolled domestic transmission of the virus since before that time. However, in just the first half of 2025 the U.S. has reported more cases of measles – 1,309 confirmed cases as of July 15 – than in any year since 1992. In addition, state and local health departments, which have key responsibilities for measles prevention and response efforts across the country, are contending with reduced support from the federal government under the current administration and staffing and budget cuts in many jurisdictions. Further, the past few years have seen more skepticism among the public about the safety and effectiveness of measles vaccines and a decline in trust of health authorities in general, contributing to lower vaccination rates and complicating outreach and communication efforts to combat measles.
What does this mean for U.S. elimination status and control of the disease going forward? This policy watch provides an overview of measles elimination, including how this status is decided and declared, and its significance. Further, we assess how the current measles outbreak may threaten elimination status and what that might mean for control of measles in the U.S.
Measles and the Measles Vaccine
Measles is one of the most contagious human viruses. When spreading in a population with no prior immunity, it is estimated that on average one measles case can result in 12- 18 other cases (this is the basic “reproduction number” of measles). While most measles infections are not severe, health complications can occur in about 30% of measles cases, and around 1 in 1,000 measles infections lead to death. There is a higher risk of severe outcomes in young children and immunocompromised individuals. Among the 1,309 confirmed measles cases so far in 2025, 164 (13%) were hospitalized and three deaths have occurred. Besides the risk of the infection itself, measles can also have long-lasting negative impacts on the immune system more broadly, especially in children, leaving people more prone to serious outcomes from other infections. Those who recover from a measles infection usually develop long-term immunity to further measles infection.
Measles vaccines have been available in the U.S. since 1963 and are safe and effective at providing protection against illness and, importantly, against infection and onward transmission of the virus. It is estimated that two doses of a measles-containing vaccine are 97% effective in preventing infection. CDC recommends children get their first measles vaccine dose between 12 and 15 months of age, and the second dose between 4 and 6 years of age, before entering school. Currently, the most common measles-containing vaccine in the U.S. is the combination measles, mumps and rubella (MMR) vaccine. Epidemiologists estimate that when >95% of a population has immunity to measles, through previous infection or vaccination, then “herd immunity” is reached and measles transmission is interrupted and large outbreaks will not occur. Therefore, at least 95% coverage with two doses of the measles vaccine is a common goal for immunization campaigns and is the current Healthy People 2030 target in the U.S. However, it was estimated that national two-dose MMR coverage in the United States is for children entering kindergarten in 2023 was 92.7%, a figure that had declined from 94.7% in 2011. In addition, this coverage varied significantly across states, ranging from 79.6% in Idaho to 98.3% in West Virginia. Just 11 states had reported coverage levels at 95% or above in 2023-2024. So far in 2025, 92% of measles cases have occurred in unvaccinated individuals.
National, Regional, and Global Measles Elimination Goals and Prior U.S. Certifications
The first national goal to interrupt measles transmission in the U.S. was announced in 1966, just a few years after licensure of the first measles vaccine, and CDC announced further measles elimination goals in 1978 and 1993. In 1994, the member states of the Pan American Health Organization (PAHO, the Americas regional office of the World Health Organization (WHO) that includes the U.S.) set a goal of interrupting endemic measles virus transmission in the region by the year 2000 and in 2012, member states of the WHO endorsed a Global Vaccine Action Plan that included a measles elimination goal for all six WHO regions by 2020.
Despite setting multiple goals since 1966, the U.S. did not officially achieve measles elimination status until 2000. Verification of elimination was carried out first through internal CDC and external expert review of U.S. strategy and programs to address measles, and epidemiological data on cases and vaccinations, which were compared against predetermined benchmarks for success. In March 2000, the National Immunization Program at CDC convened an external panel of experts to review the available data, and the panel concluded that criteria for elimination had been met, and officially stated that measles had eliminated from the U.S. Subsequently, a process was undertaken to re-verify U.S. elimination status in 2011, when the CDC’s National Center for Immunization and Respiratory Diseases assembled panel of external experts to review available evidence on U.S. measles programs and epidemiology since 2000. The panel agreed that measles elimination had been maintained, issuing a final report in March 2012. The U.S. has continued to review measles elimination status over time, including through an external expert committee known as the U.S. National Sustainability Committee for the Elimination of Measles, Rubella, and Congenital Rubella Syndrome.
Given the region-wide goal set in 1994, PAHO has also reviewed and verified national measles elimination for countries of the Americas, including the U.S. In 2007, PAHO member states created an international committee to verify country-level interruption of measles transmission and called for the creation of national-level commissions to help compile and submit related documentation to PAHO for review by an expert committee. Subsequently, PAHO’s Measles and Rubella Elimination Regional Monitoring and Re-Verification Commission (MRE-RVC) has met regularly to review available evidence and issue reports on the status of elimination in PAHO member states with the U.S. consistently being designated as having “sustained elimination,” including in its most recent report from November 2024.
What Does it Mean to “Eliminate” Measles?
According to the guidelines developed by the U.S. and other PAHO member states, measles elimination has been defined at a basic level as: “Interruption of endemic measles virus transmission for a period greater than or equal to 12 months, in the presence of high-quality surveillance.” By contrast, measles is considered endemic in a given area if there is continuous transmission over a 12-month period.
In their review processes, CDC and external experts have used a variety of epidemiological and programmatic indicators, such as measles cases and transmission patterns, public health measures and response capabilities, and vaccination rates to help determine if endemic measles transmission has been “interrupted” and whether surveillance is “high-quality.” For example, when experts reviewed data for re-certification of measles elimination for the U.S. in 2011, the following primary lines of evidence were used (most covering the period 2001 to 2011) and the committee decided collectively that the data supported the conclusion that endemic measles virus transmission was interrupted in the presence of high-quality surveillance:
- There were fewer than one reported measles case per 10 million population;
- The great majority of measles cases were imported from areas outside the U.S. and most imported cases did not lead to further spread inside the U.S. – over the study period, 40% of cases were found to be imported;
- The number and size of measles outbreaks over that period were small: a total of 64 outbreaks (median 4 outbreaks/year), with a median outbreak size of 6 cases. Only 16 outbreaks included 10 or more cases;
- Measles vaccination rates among children had been sustained at high levels (>95%) over the study period, with no significant differences in coverage by race/ethnicity;
- Data from national surveys indicated that population immunity to measles was above the “herd immunity” threshold; almost all age groups had seropositivity rates for measles antibodies over >95%, and;
- Programmatic data on laboratory testing and case investigation performance indicated that U.S. surveillance adequately and quickly identified measles cases and transmission chains.
Prior to 2025, the largest outbreak of measles since U.S. elimination was declared occurred in 2018-2019. Imported measles cases in late 2018 had started a large outbreak centered in several close-knit communities with low vaccination rates in New York City and surrounding counties. As more measles cases came to be identified, state and local officials began to implement public health measures to combat the outbreak including declaring a public health emergency, mandating vaccinations and instituting fines for parents not vaccinating their children, which led to 60,000 MMR vaccine doses administered in affected areas in a few months. Authorities also closed schools where measles transmission occurred, prohibited unvaccinated children from attending school, and engaged in extensive communication and outreach efforts. At the time, federal agencies such as CDC provided technical assistance and other support and made clear statements about the importance of measles vaccinations, with then-CDC Director Robert Redfield stating “I encourage all Americans to adhere to CDC vaccine guidelines in order to protect themselves, their families, and their communities from measles” and pointing out that “organizations had been deliberately targeting these communities with inaccurate and misleading information about vaccines.” The White House also echoed this, with President Trump stating “vaccinations are so important” and encouraging parents to vaccinate their children against measles. These combined efforts were effective in containing the New York outbreak in under 12 months, as transmission was interrupted by August 2019.
Does the Current Outbreak Threaten U.S. Measles Elimination Status?
In the first half of 2025 alone the U.S. has had more measles cases, outbreaks, affected states, and deaths than in any year since 1992. In addition, although many of the U.S. outbreaks this year began with imported cases, a higher percentage of cases are due to local transmission vs. importation compared to previous years. Further, U.S. MMR vaccination rates have declined to levels below that needed for herd immunity. While the pace of reported measles cases has declined since a peak earlier this year, outbreaks are ongoing and more states are reporting outbreaks over time. According to CDC data, as of July 15, 2025 there have been:
- 1,309 confirmed measles cases, or approximately 3.8 cases per million population
- 40 states with confirmed measles cases, with 16 states reporting 10 or more cases
- 29 outbreaks (defined as 3 or more related cases)
- 12% of cases imported
- 164 hospitalizations and 3 deaths from measles
Compared to the elimination period of 2001 to 2011 discussed above, each of these metrics is significantly worse. There were 64 measles outbreaks in total over ten years (2001 -2011) but in the first 6 months of 2025 there have already been 29 outbreaks. While 40% of measles cases were imported in the 2001-2011 period, in 2025 just 12% of cases were imported (meaning more local transmission chains). There was one measles death over ten years during the elimination period, while there have already been three already in 2025. Many data points this year are also worse than those from 2019, when U.S. measles elimination status was last threatened. For example, from January to October 1, 2019 (by which time the large outbreaks centered in New York had been contained), there had been 1,249 total measles cases, and 22 total outbreaks across 17 states; in 2025 those numbers have already been surpassed.
Primary responsibility for public health responses to measles sits with state and local health departments. At the moment, metrics on state and local capacities and response times for measles are not available, so gauging whether U.S. surveillance remains “high-quality” is challenging. However, in 2025, state and local public health departments have faced significant cuts in funding and support from the federal government compared to previous years, which may impact their ability to track and respond to measles outbreaks. In recent years, the federal government has provided over half of state and local health public health departments’ budgets. There is little evidence that states most affected by measles in 2025, such as Texas and New Mexico, have taken the kinds of measures that New York officials implemented to contain outbreaks in 2019: vaccination mandates, school restrictions and fines. While federal agencies such as CDC have been providing technical assistance and funding to affected areas in 2025, HHS Secretary Robert F. Kennedy, Jr. has downplayed the risks of measles and has provided mixed messages about the importance of vaccination compared to alternative treatments for measles.
Data also show that national measles vaccination levels declined over the past five years, with kindergarten and childhood measles coverage rates dipping well below the 95% goal. Measles vaccination rates for kindergarteners at the national level declined from 95.2% in 2019-2020 to 92.7% in 2023-2024 (the latest available data), and over three-quarters of states had MMR vaccination rates below the target rate of 95% in the latest data. Additional studies have found that 78% of U.S. counties reported a decline in two-dose measles vaccine coverage in children, with the average county-level measles vaccination rate falling from 93.9% in 2019 to 91.3% in 2024. In 2025, 8% of U.S. measles cases had history of MMR vaccination while 92% of cases were unvaccinated or had unknown vaccination status. These lower MMR vaccination rates have occurred in the context of broad declines in people’s trust in health authorities and in vaccinations in general. For example, KFF polling has found that parents are frequently exposed to misinformation about measles and the MMR vaccine, and in 2025 almost 20% of adults report they believe the false claim that “getting the measles vaccine is more dangerous than become infected with measles” is probably or definitely true.
Therefore, if current trends hold through the rest of the year there would appear to be grounds for the U.S. to lose measles elimination status, using prior definitions and benchmarks.
U.S. Measles Outbreaks in a Regional and Global Context
The U.S. is not alone in facing higher numbers of measles cases in 2025. There have also been large outbreaks in Canada (3,517 confirmed cases) and Mexico (2,597 reported cases). Similar to the U.S, these countries’ outbreaks are concentrated in communities with low vaccination rates. According to PAHO, in the region of the Americas a total of 7,132 confirmed cases of measles and 13 deaths from measles infections have been reported as of mid-June, with almost all coming from North America. WHO reports that through June of this year, there have been a total of 108,074 measles cases globally with large outbreaks occurring in the European and Eastern Mediterranean regions, in addition to the Americas. Outside of North America, the countries with the highest numbers of measles cases in 2025 include Yemen (15,683 cases), Pakistan (12,732), and India (10,299). More circulation of measles regionally and globally means a higher risk that U.S. residents traveling internationally can be exposed, which raises the risk of importing measles and sparking new domestic outbreaks.
Looking Ahead
The elimination of measles in the U.S. was a notable public health achievement made possible by sustained investments in prevention and response capacities, support of vaccination, and commitment to the goal of elimination. However, this status is currently at risk, as demonstrated by the many factors discussed above. Losing measles elimination status would signify that the same commitment to measles prevention and control may no longer be present in the U.S. It could signify a future where measles is endemic and continuously circulating, especially if vaccination rates continue to decline. That would bring more hospitalizations and more deaths, particularly among vulnerable children, from a very preventable disease. There could be broader implications for communities across the country, which may have to contend with more frequent decisions about whether and when to close day cares and schools in the face of transmission risks. The societal costs of measles outbreaks are high, so continuous outbreaks would place an additional burden on already weakened and depleted public health systems, and would raise questions about what the appropriate level of support and funding should be from the federal government for outbreak response at the state and local levels.
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