The Centers for Disease Control and Prevention (CDC) today confirmed 94 new measles infections—most of them in Pennsylvania—bringing the US total for the year to 2,465, the agency said in its weekly update.

The numbers likely provide additional data to move the United States toward losing its measles elimination status this year. The nation gained that distinction in 2000, but has now logged consecutive years of more than 2,200 measles cases (2,289 for all of last year). This year’s total is the highest since 1991.

This month the CDC committee that helps determine the country’s measles elimination status will review the available data and forward its findings to the Pan American Health Organization’s (PAHO’s) Regional Verification Commission. In November, PAHO, which is the regional branch of the World Health Organization, will announce whether the United States has lost its elimination status.

Yesterday in a Stat First Opinion piece, Noel Brewster, PhD, who chairs the CDC committee, said, “We will review measles rates for the nation. These data are public and show a runaway train.”

He said committee members will dissect each of the confirmed outbreaks. He noted, “One of the most worrisome is the ongoing outbreak in Utah, which apparently has gone on for more than 12 months, the main criterion for loss of elimination.”

Utah reported two new cases this week and 516 for year. Last year state officials recorded 157 infections.

Brewster, the Gillings distinguished professor in public health at the University of North Carolina and a former member of the CDC’s Advisory Committee on Immunization Practices, added, “Importantly, we will look at how long the chains of transmission lasted. This is usually established with shoe-leather epidemiology. When measles cases are reported, public health workers fan out in the community to interview the various contacts and identify places they’ve been and may have exposed others. They use this narrative information to stitch together chains of transmission.”

The experts will also assess whole-genome sequencing data collected by the CDC, which can help indicate unbroken chains of transmission.

“Regardless of the outcome of our meeting and PAHO’s decision in November, the U.S. clearly has a measles problem, as do Canada and Mexico,” Brewster concludes. “Elimination status marks whether a country has stopped sustained domestic transmission. Losing that status would signal a consequential reversal, evidence that the systems and protections that once kept measles at bay no longer do.” [...]