Measles Strain Spreads Across Multiple States, Putting U.S. Elimination Status at Risk

On a call among health officials, a recording of which was later obtained by The New York Times, the message was that the measles strain that has been moving through Texas since January has now reached Utah and Arizona. That finding puts the United States on a path toward something it has not experienced in 25 years: the loss of its measles elimination status.

The rule is simple. A country loses the designation when the same strain circulates for 12 months or more. The strain in question, identified as 9171, was first detected on Jan. 20 in Gaines County, Texas. The outbreak began in a conservative Mennonite community in western Texas and expanded to Oklahoma and New Mexico. Dr. David Sugerman, who leads the CDC's measles response, said the strain has continued "uninterrupted, across multiple jurisdictions." If transmission carries into January, the one-year mark, the status the U.S. has held for more than two decades could be gone.

Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told The Times he would not yet call a code, but added that the patient is not looking real good. Canada offers a recent precedent. It lost its 27-year elimination status last week after failing to contain a large outbreak that began at a Mennonite gathering in October 2024.

The Utah-Arizona outbreak is now the largest in the country, with more than 180 cases. Most infections occurred within households, but roughly 25% have no identified source, which suggests transmission through channels officials have not traced. About 7% occurred at large events such as weddings and festivals. Local officials in Utah say efforts to raise vaccination rates have had only limited success: rates rose initially and then slowed again.

The national numbers show the scale. As of Nov. 13, the CDC had confirmed 1,723 measles cases, 87% of them tied to a record 45 outbreaks this year. In 2024 there were 16. About 92% of those infected this year were unvaccinated or had an unknown vaccination status. The country has also recorded 152 imported cases from at least 47 countries, including eight new importations in the last two weeks.

Not every front is worsening. An outbreak tied to two schools in South Carolina appears close to being contained. Rockland County, New York, has reported four cases, its first since a major outbreak in 2018. Response teams are still tracking and trying to contain new cases.

Andrew Nixon, a spokesperson for the Department of Health and Human Services, said in a statement that the CDC and state and local agencies continue to assess transmission patterns and mount an effective response, which he said led to the Texas outbreak being declared over. Sugerman said the overall risk of widespread measles transmission in the United States remains low.

Experts say losing elimination status may not bring immediate practical changes, but it carries weight: it shows that a wealthy country with strong medical resources allowed a disease to keep spreading. Dr. David Kimberlin, a pediatric infectious disease specialist at the University of Alabama who sits on the panel that reviews U.S. status, told The Times he would not be surprised by continued spread over the next several months. The question to watch is whether strain 9171 is still circulating when January arrives.