Idaho has the lowest measles vaccination rate in the United States, with only 78.5 percent of its population fully vaccinated against the MMR virus. This figure falls far short of the 95 percent coverage needed for community immunity. Health officials are concerned that the state's high exemption rate limits potential vaccination coverage to approximately 85 percent.
While Idaho has reported only nine measles cases since early 2026, all affecting unvaccinated individuals or those with unknown status, recent undetected cases are suspected. Last August, three cases were identified with no clear link, suggesting further community spread.
Health officials are urging residents to get the MMR vaccine, noting that two doses are 97 percent effective and provide lifelong protection. The vaccine is recommended for children at 12-15 months and again at 4-6 years of age.