Hamilton County Public Health (HCPH) is urging residents to check whether they are up to date on their measles vaccinations as Ohio's case count climbs.

The department published an advisory Wednesday, Sept. 9, warning that measles outbreaks are growing more frequent in Ohio and neighboring states. The advisory applies to all Hamilton County residents, including those in Montgomery, Blue Ash and Sycamore Township.

The U.S. has recorded 3,134 confirmed measles cases in 2026 as of Sept. 3, according to the Centers for Disease Control and Prevention. That already surpasses the full-year 2025 total of 2,289 and marks the highest annual count since 1991.

Ohio had confirmed 142 cases across 15 counties as of approximately Aug. 21, according to CIDRAP reporting citing Ohio Department of Health data. Ashtabula County led the state with 40 infections. No confirmed Hamilton County cases appear in the advisory, but HCPH said it is monitoring for local outbreaks.

Among all U.S. measles patients this year, 94% are unvaccinated or have an unknown vaccine status, CIDRAP reported. National kindergarten MMR (measles, mumps and rubella) vaccination coverage fell from 95.2% during the 2019–2020 school year to 92.4% in 2025–2026, leaving roughly 280,000 kindergartners at risk, according to CDC data.

Measles spreads easily. An infected person can pass the virus to up to 90% of unvaccinated people they encounter, according to HCPH. The two-dose MMR vaccine series is 97% effective at preventing measles. One dose is 93% effective.

The Ohio Department of Health recommends all residents verify their vaccination status, especially families with children, according to the HCPH advisory. Adults born after 1957 or vaccinated before 1968 may have less protection and should discuss a booster with their doctor, according to an HCPH fact sheet.

Symptoms typically appear 7 to 14 days after exposure and include fever, cough, runny nose, pinkeye and a blotchy red rash. Anyone who suspects exposure should call a healthcare provider and their local health department immediately.

HCPH can retrieve immunization records for residents. Call (513) 946-7800 or complete an online records request at the department's website, 250 William Howard Taft Road, 2nd Floor, Cincinnati. Measles vaccinations are typically covered by health insurance, including marketplace and most private plans, according to HCPH.