Measles is back in the United States, WHO authorities say
Measles is officially back in the United States after the disease had been eliminated from the country for more than 25 years.
Key points
- The PAHO's meeting to reevaluate the United States' status was originally scheduled for April but was pushed to November.
- The effort rests largely on keeping vaccination rates above a critical threshold — because the measles virus spreads so easily, at least 95% of the population needs immunity via either vaccination or past infection to prevent large outbreaks from occurring and fueling uncontrolled spread.
- Everything you need to know about immunity Measles wipes your immune system's 'memory,' so it can't fight other infections In survivors, measles can cause long-term health problems, including brain damage and immune amnesia, in which the immune cells tasked with remembering past infections have their "memories" wiped.
The Pan American Health Organization (PAHO), which is the regional office of the World Health Organization for the Americas, has reevaluated the United States' measles elimination status and determined that it should be revoked.
National measles vaccination rates have been falling in recent years, with just 10 states reporting rates above the immunity threshold among kindergarteners for 2025-2026.
Additional details
- (Image credit: CDC/ Rebecca Martin, PhD) The nation's first measles-related deaths this year were reported in Pennsylvania in August, and five more have followed, according to state health officials.
- (Some of these deaths have not been confirmed by the federal government.) A death reported in Wisconsin and another in New York have brought the current total to eight, per states' counts.
- Travelers would occasionally bring measles into the country, sometimes sparking significant local outbreaks, but these didn't tip enough dominoes to lead to ongoing domestic transmission.
- officially eliminated measles in 2000, meaning that at that time, the country had gone over a year without continuous domestic spread of the disease.
- "I do want to just stress that measles elimination has always been a tenuous prospect, and it is, by design, tenuous," she added.
How this summary was made: extractive summary — built from the sources' own reporting. It is drawn only from the reporting of the sources listed below — read the originals for full detail. How we summarize →
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