Key development
The Pan American Health Organization (PAHO) has revoked the United States’ measles-elimination status, concluding that the country did not interrupt continuous local transmission of the virus for a period of 12 months or longer. The move ends a designation the United States had held for 26 years.
How the determination was reached
PAHO evaluated epidemiological and laboratory evidence submitted by the U.S. Centers for Disease Control and Prevention (CDC) to assess whether a single strain of measles had been circulating uninterrupted in the United States for at least a year - a hallmark of local transmission rather than isolated imported cases. That review found the criteria for sustained transmission were met.
Officials involved in the review determined the evidence indicated at least 12 months of continuous transmission. The CDC’s internal report and an independent advisory panel’s assessment were presented to PAHO during the review process; the panel’s presentation and the CDC’s submission remain confidential.
Current outbreak figures and context
The United States is experiencing its largest number of measles cases in more than three decades. Since 2025, roughly 7,500 people in the United States have been infected and 13 people have died, figures that coincide with falling immunization rates. Through Thursday of the current year, 5,182 confirmed cases had been reported to the CDC from 45 states, New York City and the District of Columbia, surpassing the 2,289 cases recorded for the prior year and placing the outbreak among the worst in decades.
Public health response and official statements
The director of the CDC, Dr. Erica Schwartz, said in an interview before PAHO’s decision that if the United States lost its measles-elimination designation the agency would continue doing "the same exact thing," meaning ongoing work with states to encourage immunization. The Department of Health and Human Services did not provide a comment in response to a request.
Noel Brewer, a public health professor at the University of North Carolina who chairs an independent advisory panel on measles, described the current situation starkly: "It is a fully preventable disease. It is unconscionable that we have this amount of measles." Brewer presented the CDC’s measles status report and his panel’s assessment to PAHO as part of the evaluation.
Drivers highlighted in the review
Public health authorities point to two related trends during the period of rising measles activity: declining vaccination coverage and increasing vaccine hesitancy. The review period overlaps with the tenure of the current U.S. Health Secretary, Robert F. Kennedy Jr., who has for years promoted doubts about measles vaccine safety without scientific evidence, a factor cited in assessments of the outbreak environment.
Consequences and what restoration requires
Experts say the revocation represents a reputational setback for U.S. public health. William Moss, an epidemiology professor at the Johns Hopkins Bloomberg School of Public Health, said the loss of elimination status damages the United States’ standing and could discourage other countries. For the public, he added, the practical result is that large outbreaks are likely to continue, exposing people to infection, hospitalization and death.
To regain measles-elimination status, the United States must end continuous transmission and remain free of measles outbreaks for at least 12 months.
Broader regional context
PAHO’s action comes after other countries have undergone similar re-evaluations by global health experts. In recent reviews, Canada, Spain and the United Kingdom were determined to have lost measles-elimination status. Separately, the United States previously withdrew from the World Health Organization, although it remains a member of PAHO, the WHO’s Americas branch.
Vaccine effectiveness and public health thresholds
Public health guidance notes that herd immunity against measles typically requires around 95% vaccination coverage to halt transmission. Two doses of the measles vaccine deliver strong protection, providing about 97% effectiveness against infection and transmission. Measles itself can cause severe complications, including blindness, deafness, brain damage or death, underscoring why prevention through vaccination is the primary control strategy.
Outlook
U.S. public health agencies indicate they will continue efforts to increase vaccination rates and work with state partners to contain transmission. The timeline for restoring elimination status depends on successfully interrupting chains of transmission and maintaining that interruption for at least 12 months, a condition that remains challenging while measles activity continues at elevated levels.