The United States is approaching 2,000 confirmed cases of measles this year, the highest number since 1992. Next month, scientists will determine whether outbreaks across the country have spread continuously throughout 2025. 

If so, the United States is poised to lose its measles-free status, entering an era in which outbreaks are common again. 

Specifically, researchers are analyzing data to learn whether the ongoing outbreaks in Utah (115 cases), Arizona (176 cases), and South Carolina (114 cases) stemmed from the large outbreak in West Texas that officially began on Jan. 20 (762 cases).

At first glance, many of the country’s outbreaks appear to be connected because they’re caused by the same strain of measles, D8-9171. But this strain is also spreading throughout Canada and Mexico, which means the outbreaks could have been sparked separately from people infected abroad. If that happened, this technicality could spare the United States from losing its status.

To discern between these two possibilities — continuous versus separate outbreaks — scientists are studying the entire genomes of measles viruses, which contain all their genetic information, instead of looking at only a short snippet of genes that mark the strain. Genetic mutations occur naturally over time, and small changes in genomes from different outbreaks can be revealing. 

For example, if one child directly infects another, the kids will have matching measles viruses. But measles viruses infecting people at the start of a large outbreak would be slightly different than those infecting people months later.

Kelly Oakeson, a genomics researcher at the Utah Department of Health and Human Services, is conducting these analyses now. “We are working with the CDC and other states to determine whether what we’re seeing is one large outbreak with continued spread from state to state,” Oakeson said.  

Although the Texas and Utah outbreaks were caused by the same strain, he said, “more fine-grained details are leading us to believe they aren’t super closely related.” 

The U.S. Department of Health and Human Services has also highlighted this result. Notably, it may have the power to spare the United States from losing its status.

“Preliminary genomic analysis suggests the Utah and Arizona cases are not directly linked to Texas,” Deputy HHS Secretary Jim O’Neill wrote on the social platform X.

However, I spoke with some researchers who worried that the Trump administration may be more concerned with genomic arguments than combating and preventing measles outbreaks. 

“It will be quite a stain on the [Robert F.] Kennedy regime if he is the health secretary in the year we lose elimination status,” said Demetre Daskalakis, a former director of the Centers for Disease Control and Prevention’s national immunization center, who resigned in August. “I think they will do everything they can to cast doubt on the scientific findings, even it means throwing scientists under the bus.”

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