Utah measles exposure prompts rapid post-exposure treatment for 11 infants

Public health officials in Utah are racing to protect 11 infants who were exposed to measles at a Logan medical office after a patient with the virus visited the clinic on Monday, Sept. 15, according to Bear River Health Department. Logan is about 80 miles north of Salt Lake City.

All of the infants were under one year old, meaning they are too young to receive the measles, mumps and rubella (MMR) vaccine. Officials said they do not release the infected patient’s age.

The MMR vaccine is given in two doses to children between ages 12 and 15 months and again between ages four and six, a schedule designed to maximize protection. Utah maintains a stock of post-exposure prophylactic (PEP) globulin, an antibody-based treatment used to provide short-term protection against measles and other diseases, but it must be administered within six days of exposure to be effective. Bear River Health Director Jordan Mathis told local media that they had until Sunday to get all those individuals treated, noting the rapid time frame involved.

Families were notified of the exposure by Friday, Sept. 19. In a later briefing, Mathis said the health department set up a clinic on Saturday, Sept. 20, to administer PEP. Nine of the 11 families accepted the treatment; the remaining two infants were referred to an emergency room to receive the therapy through an IV due to their small size. Mathis called the coordinated effort a strong example of communication and collaboration aimed at reducing the spread in the community.

Utah remains in the midst of a measles outbreak, with 44 people sickened by the virus in 2025, according to state health officials. Nationally, there is a larger outbreak that has totaled 1,514 cases across 42 states so far this year. About 12 percent of patients infected with measles have been hospitalized, the latest CDC data shows. The majority of cases — 803 — have been in Texas, while California has reported 20 cases. Three people, including one in Colorado and two in Texas, have died this year from the virus. The current outbreak is the largest since 2,126 cases were reported in 1992.

A map illustrating vaccination patterns shows the number of reported measles cases in Utah so far in 2025, with the southwest portion of the state reporting the highest counts. The measles vaccine is preventable and highly effective: two doses are about 97 percent effective at preventing infection. The first dose is given at 12 to 15 months, and the second at four to six years.

The United States has not achieved herd immunity nationwide. A vaccination rate of about 95 percent is needed to maintain herd immunity, but nationwide, 92.5 percent of kindergartners have received both doses. In Utah, the kindergarten vaccination rate for the two-dose schedule stands at about 89 percent, and nearly one in 10 Utah kindergartners had a personal, religious or medical exemption for at least one vaccine during the 2023-2024 school year. Health officials emphasize that high vaccination coverage remains the most effective way to prevent measles outbreaks and protect vulnerable populations, including infants who cannot yet be vaccinated.

Mathis noted that the 11 infants who received PEP will now be on a delayed MMR vaccination schedule, balancing immediate post-exposure protection with long-term immunity strategies for those too young to be vaccinated.