Several people have been infected with measles after they were exposed to the virus at an August cycling event at Soldier Hollow, the Utah Department of Health and Human Services reports.

About 2,000 people attended the Utah High School Cycling League event on Aug. 16, according to the department. Four measles cases have been confirmed among the attendees; none of them were vaccinated, the department said.

The health department said it is working with the Utah High School Cycling League to inform families and race participants of their possible exposure to measles.

The event was a competition for teen cyclists in the league’s region 6, whose teams come largely from southern Utah from St. George to Moab, and as far north as Utah County.

The Wasatch County School District issued a statement Tuesday afternoon, saying that none of the participants of the cycling event were Wasatch County residents. “There are no known measles cases in Wasatch County and the event was not connected to WCSD,” the district said.

The new cases bring the state’s confirmed total to 24, according to the health department. Only one of those was vaccinated.

Even at outdoor events, measles remains highly contagious and can spread easily, Dr. Leisha Nolen, epidemiologist for the state of Utah, said in a statement issued by the health department. She urged anyone who attended the event to check their measles-mumps-rubella vaccination status.

The MMR vaccine is 97% effective against measles when people receive two doses, according to the state’s health department.

Utah vaccination data among kindergarteners shows that despite the vaccine’s effectiveness, fewer and fewer students are receiving required vaccines as more parents seek exemptions for personal and religious reasons.

During the 2024-25 school year, 11.2% of all Utah kindergarteners — and 9.9% of in-person kindergarten students — were not adequately vaccinated for measles, according to state data.

Measles symptoms typically appear one to two weeks after exposure, according to the health department. They include a moderate fever accompanying a cough, runny nose and red, watery eyes. A few days later, the department said, the fever spikes to 101 degrees or higher and a rash appears along the hairline before spreading to the rest of the body.