Two hot spots for measles activity in the United States—neighboring counties in Arizona and Utah and Upstate South Carolina—are reporting more measles cases, and the Centers for Disease Control and Prevention (CDC) says the United States now has 1,648 confirmed cases this year, 87% of which are outbreak-associated.
The national total is 30 more cases than last week.
13 more cases in Utah-Arizona
In the growing outbreak in Utah and Arizona, the Southwest Utah Health zone now has 45 measles cases, 1 more than last week. Mohave County, Arizona, now has 93 confirmed cases, a 13-case increase since last week. In total, the Utah-Arizona outbreak now stands at 138 infections, compared to 124 last week.
The Utah-Arizona outbreak is the second largest outbreak of the year so far, following the West Texas outbreak this past spring that sickened more than 750 people. Both outbreaks started in rural communities with historically low vaccination rates.
In South Carolina, officials yesterday confirmed 8 more cases in the past few days in Spartanburg County. The state now has 33 cases in 2025, 30 of which are part of the Upstate outbreak that was linked to two elementary schools with low vaccination rates among students.
All eight new cases were linked to close contacts of known cases, and the patients had been quarantining at home when they were diagnosed, officials said. Mobile immunization units will be open this week in the affected counties to boost coverage with measles, mumps, and rubella vaccines.
In other developments, Washington state has its 12th case of the year in a King County resident. The adult was exposed to measles on a flight earlier this month.
Two thirds of US cases in US in kids, teens
Cases in the United States are still most common in people 19 years and younger, with children under the age of 5 making up 27% of cases, and children 5 to 19 years making up 40% of cases, for a total of 67%, the CDC said today. Ninety-two percent of US cases are in unvaccinated people or those with an unknown vaccine status.
Twelve percent, or 202 of 1,648 measles patients, have required hospitalization, and there have been 3 deaths.
Editor's note: This story and headline were corrected on October 30. Total US cases grew by 30, not 40 as previously reported. We apologize for the error.
