Current largest outbreak of measles keeps growing

Stephanie Innes

Arizona Republic

USA TODAY NETWORK

An outbreak of measles on the Arizona-Utah border continues to grow, with the latest data showing 201 cases and eight hospitalizations.

Numbers released Nov. 18 by the Arizona Department of Health Services show that measles cases in Mohave County on the Arizona side of the outbreak have climbed to 133, including three hospitalizations. That’s up by 24%, or 26 cases, from Nov. 6.

The outbreak includes southwestern Utah, which is up to 68 cases, including at least five hospitalizations, data from Utah health officials shows. It is the second-largest outbreak in the country in 2025. A measles outbreak in West Texas earlier in 2025 infected 762 people in Texas and spread into Oklahoma and New Mexico, too.

The deaths of two children and one adult have been linked to the Texas outbreak, which was concentrated in a community with a large rate of unvaccinated individuals.

Measles is a highly contagious, potentially fatal airborne virus that can affect people of any age and cause an array of complications, including deafness, blindness and brain inflammation.

The Arizona-Utah outbreak’s first cases were reported in August in the southwestern Utah community of Hildale and in the rural northern Arizona community of Colorado City in Mohave County. Hildale and Colorado City are in different states, but they operate as one community, local residents say.

The overall majority of the cases in the outbreak are among children and youths, JP Martin, a spokesperson for the Arizona health department, wrote in an email.

Two doses of the MMR vaccine are 97% effective in protecting against measles infection, evidence shows. The vaccine with the lowest uptake for Arizona kindergarten students is consistently MMR, or measles, mumps and rubella. Colorado City schools have extremely low rates of vaccine uptake, state data from the 2024-25 school year shows.

Past public warnings of exposure sites during the outbreak have included a market in Colorado City and an elementary school, an urgent care and hospitals in southwest Utah.

Public health officials in Maricopa County recently warned the public about possible measles exposure sites in the Phoenix area, including at a Nov. 5 sold-out Tate McRae concert, and Coconino County health officials issued a warning about measles exposure at the Flagstaff Mall. To date, no measles cases have been confirmed in Maricopa or Coconino counties.

The United States had confirmed 1,753 measles cases as of Nov. 19. Ninety-two percent of the confirmed measles cases in 2025 occurred in unvaccinated individuals, CDC data shows, and 211 of the infected people in the United States, or 12%, have been hospitalized. One hundred of the people hospitalized with measles have been under the age of 5, CDC data shows.

The past few years have seen more skepticism and confusion among the American public about the safety and effectiveness of vaccines, a decline in trust of health authorities, and a growing partisan divide on health issues, according to a Sept. 12 policy update from KFF, an independent health policy research, news and polling organization.