US loses measles elimination status as cases surge, vaccination levels fall

Resumen detallado

Thanks to widespread vaccination, measles had been considered "eliminated" as a continually transmitting illness in the United States since 2000 - but not anymore.

Thanks to widespread vaccination, measles had been considered "eliminated" as a continually transmitting illness in the United States since 2000 - but not anymore.

An independent commission of experts that reports to the director of the Pan American Health Organization determined that the US no longer qualified as having eliminated measles, a source close to the process told CNN on Friday.

The decision was widely expected after years of falling vaccination levels and surging case counts, but it's still a black mark on the nation's public health policy.

The international committee that determines countries' measles elimination status considers an infection to be endemic, or regularly occurring, if infections caused by the same strain are passed from person to person for at least a year within the same country.

To determine this, the committee members look at the genetic code of viruses sampled from patients.

Every time a virus copies itself, it makes tiny changes in its genetic code. By studying the genomes of different viruses in an outbreak, scientists can determine how closely the infections may be related and whether they are likely to have been part of the same chains of transmission.

In August, scientists with Utah's public health laboratory published a preprint study showing that the same strain of measles had been circulating in the state for more than a year, accounting for more than 95 percent of cases there. It travelled from the southwest part of the state to central Utah, ultimately causing more than 600 cases between June 2025 and June 2026.

There have also been sustained outbreaks in South Carolina, Pennsylvania, Wisconsin and New York, as well as other states.

It's not clear what data the committee relied on to make its decision, but it wasn't exactly a tough call, Dr Angela Rassmussen, a virologist at the University of Saskatchewan in Canada and editor-in-chief of the journal Vaccine, said.

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