Wisconsin health officials are encouraging families to check their children’s vaccination records as measles continues to spread in parts of the state.
Wisconsin has confirmed 167 measles cases in 2026, according to the Wisconsin Department of Health Services (DHS). The largest cluster is in southwestern Wisconsin, where an ongoing outbreak has been reported across Grant, Iowa, Lafayette, and Vernon counties. As of September 18, DHS reported 158 confirmed and 6 probable cases connected to that outbreak.
Health officials say the outbreak is spreading locally, while local health departments are working to identify people who may have been exposed and increase access to vaccination.
Low vaccination rates remain a concern
Vaccination coverage varies considerably among communities affected by the outbreak.
According to Wisconsin Public Radio, only 42% of two-year-olds in Vernon County had received at least one MMR dose last year. The rate was 60% in Lafayette County, 64% in Grant County, and 81% in Iowa County.
The statewide vaccination rate among Wisconsin kindergarteners was 85.1% during the 2025–26 school year, according to DHS. That was a slight increase from 84.8% the previous school year, but it remained below the 95% level generally needed to prevent measles from spreading within a community, according to the agency.
DHS also reported that the percentage of Wisconsin kindergarteners with non-medical vaccine exemptions increased from 6.3% in 2024–25 to 7.3% in 2025–26.
Local health departments increase vaccination efforts
Health departments in affected communities are responding by making vaccines more accessible and reaching out to families.
Wisconsin DHS Immunization Program Manager Stephanie Schauer said local health departments are reporting increased interest in measles vaccination from people who had previously not been vaccinated. Some departments are providing vaccines in the community and planning vaccination opportunities in schools.
School nurses are also checking students’ immunization records and contacting families when children need to become up to date on their vaccinations, according to WPR.
DHS has encouraged Wisconsin families to check their children’s vaccination records through the Wisconsin Immunization Registry or by contacting their healthcare provider.
New cases reported outside the main outbreak area
The spread has also raised concerns about cases appearing outside the four-county southwestern Wisconsin outbreak.
DHS reported one confirmed measles case in Marathon County as of September 18. The agency said that case was associated with out-of-state travel and was not connected to the other Wisconsin cases at that time.
Two measles cases were also recently reported in Vernon County, according to WPR. Health officials were investigating whether those cases were connected to the existing southwestern Wisconsin outbreak.
DHS is continuing enhanced surveillance and exposure investigations as health officials monitor the situation.
MMR vaccine provides strong protection against measles
The measles, mumps, and rubella vaccine remains the primary tool for preventing measles infection.
The Centers for Disease Control and Prevention says one dose of measles vaccine is about 93% effective, while two doses are about 97% effective at preventing measles. The CDC recommends two doses of MMR vaccine for children.
Nationally, the CDC reported 3,294 confirmed measles cases in the United States as of September 10, 2026. About 95% of those confirmed cases were associated with outbreaks.
For Wisconsin families, health officials continue to encourage people to check vaccination records and speak with healthcare professionals about any needed vaccinations.
📊 KEY STATISTICS
Wisconsin measles situation — September 18, 2026
- 167 — confirmed measles cases in Wisconsin in 2026
- 158 — confirmed cases in the southwestern Wisconsin outbreak
- 6 — probable cases in that outbreak
- 85.1% — Wisconsin kindergarten MMR vaccination rate in 2025–26
- 95% — coverage level generally needed to prevent measles from spreading in a community
- 97% — effectiveness of two MMR doses against measles
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Credits: Vecteezy
Sources: Wisconsin Department of Health Services and CDC.