After several months of declining measles cases in Arizona, the state reported a slight increase in transmission in June.
Measles has been spreading in Arizona since August 2025. According to the Arizona Department of Health Services, monthly case counts reached a peak in December, when the state confirmed 54 cases. Case counts fell each month through May, when the state reported only six cases. But the tally increased again in June, when nine cases were confirmed.
Of the 332 cases reported in the state throughout 2025 and 2026, the majority — 285 cases — have been in Mohave County. That outbreak has ended. Mohave County has now gone more than two months without any new cases.
But the extremely contagious virus is still appearing in other parts of the state.
Pinal and Maricopa counties confirmed new cases this week. And Yavapai County on Wednesday confirmed its first measles case of 2026. Yavapai County health officials are also warning of recent potential public measles exposures at sites throughout the Prescott area.
Will Humble with the Arizona Public Health Association said the once-eliminated virus is likely to continue spreading in the state.
“It’s going to happen off and on for a long, long time because vaccination rates are just not sufficient anymore to stop and prevent the spread of measles,” he said.
The MMR vaccine provides strong, lifelong protection from measles. About 96% of Arizona’s cases over the past year have been among unvaccinated people, according to the state health department.
But measles is so contagious that at least 95% of the population needs to be immune in order to contain its spread, according to medical experts.
Statewide, vaccination rates are below the 95% herd immunity threshold — as of 2025, about 89% percent of the state’s kindergarteners were fully vaccinated for measles, according to the Arizona Department of Health Services.
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