CHAMPAIGN, Ill. — Amid an ongoing surge in measles cases across the United States, the Measles and Rubella Elimination Regional Monitoring and Re-Verification Commission of the Pan American Health Organization is scheduled to meet Nov. 10-13 in Washington, D.C. Although the commission declared measles "eliminated" in the U.S. in 2000, public health officials widely expect the commission to vote to revoke the country’s elimination status during the meeting. Molecular epidemiologist Nídia S. Trovão, a professor of pathobiology at the University of Illinois Urbana-Champaign, spoke with News Bureau Biomedical Sciences Editor Liz Ahlberg Touchstone about what elimination means and how the measles virus made a comeback in the U.S.
What does it mean to have elimination status, and how is it lost?
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Having "elimination status" means a country has interrupted the continuous, local transmission of measles for at least 12 consecutive months, supported by strong epidemiological and laboratory data. We can still see cases in an "eliminated" country because they are typically importations from international travel that result in limited, short-lived outbreaks, rather than sustained, year-round transmission.
A country loses its elimination status when evidence shows that a specific viral strain, of identical genotype and lineage, has circulated uninterrupted for 12 months or longer in a defined geographic area.
How did the U.S. reach the point where it may lose elimination status?
Given the current outbreaks, the evidence strongly points to the U.S. losing its elimination status at the upcoming November meeting. The U.S. reported the start of a measles outbreak in January 2025 that is still active as of mid-October 2026. Because this continuous transmission chain has exceeded the 12-month threshold, endemic transmission has technically been re-established. International importations can take root and establish sustained transmission when there are gaps in local population immunity, as my recent work highlights.
Why are public health officials concerned about current measles case numbers?
There have been 4,410 measles cases so far in 2026, according to the C.D.C., out of the U.S. population of more than 340 million people — much less than influenza, for example. While the number seems small relative to the U.S. population, measles is one of the most transmissible viruses known. These cases indicate pockets of low vaccine coverage. A few thousand cases can quickly snowball into large outbreaks. We are currently seeing the devastating reality of this in Bangladesh, where a severe outbreak fueled by dropping vaccination rates has infected over 200,000 people and killed over 1,100 since March 2026. As World Health Organization experts have stated, the situation in Bangladesh is a "real warning to every country" about how rapidly the disease can spread when herd immunity is compromised.
Why is a measles comeback a serious public health issue?
Measles used to be a typical childhood illness. Measles remains a major cause of death in young children and can lead to severe respiratory and neurological complications. Increased case counts are very dangerous; our recent modeling analysis found a near one-to-one correlation between increased normalized case numbers and increased deaths.
Furthermore, a measles infection causes "immune amnesia" by depleting a patient’s preexisting antibodies, which impairs the immune system’s ability to fight off other infectious diseases long after the measles infection has passed.
What is the most prevalent misinformation about measles?
The most dangerous misinformation is skepticism about vaccine safety and efficacy fueled by antivaccination movements. These narratives ignore the reality that the MMR vaccine safely provides immunity without inducing the devastating, long-term immune system depletion that a natural measles infection causes.
How can the U.S. regain measles elimination status?
To regain its status, the U.S. must first interrupt endemic transmission for at least 12 consecutive months. Following that, it must submit a formal corrective action plan to PAHO and demonstrate strengthened routine immunization reaching 95% or higher coverage, robust surveillance systems and rapid outbreak response capabilities.
