 This message is being sent to Tribal health directors, local health officers, local health department staff, local health department nurses, Vaccines for Children providers, Vaccines for Adults providers, Wisconsin vaccinators, and key DHS staff.
May 2025
Wisconsin Vaccine Preventable Disease Updates provides statewide data on select vaccine preventable diseases from the previous month.
Measles
Wisconsin has had no cases in 2025 as of April 30, 2025. The Centers for Disease Control and Prevention (CDC) has reported 935 confirmed cases of measles cases occurring in 30 jurisdictions as of May 2, 2025. CDC updates their measles case webpage weekly on Fridays. More than two-thirds of cases (68%) are under 20 years of age, 96% are unvaccinated or have an unknown vaccination status and 13% of cases have been hospitalized, with three deaths reported.
Low MMR rates in Wisconsin’s children continue to be a significant concern. Do not miss any opportunity to evaluate if children are up-to-date and provide vaccination if medically eligible. This is particularly important for families who are traveling internationally.
Moreover, providers are strongly encouraged to assess their pediatric patient populations using reports in the electronic medical record (EMR) or the Wisconsin Immunization Registry (WIR) to determine who is not up to date and conduct outreach to schedule appointments for vaccination.
MMR Resources
MMR Vaccine Does Not Cause Autism - Examine the Evidence
Pertussis
As of April 30, 2025, Wisconsin has 311 confirmed cases statewide in 2025. Since January 1, 2025, 55 counties have had at least one case. While cases range in age from 1 month to 82 years, one-third (30%) of the cases are in adolescents aged 11-18 years. Twenty-three infants have been identified with pertussis, and five have been hospitalized. No deaths have been reported. Overall, cases have been declining since the beginning of the year.
The most recent pertussis case count data can be found on the new pertussis dashboard, where users can explore trends and view data at the state, region, and county levels. Please note the data are preliminary and subject to change.
The Communicable Disease Case Reporting and Investigation Protocol: Pertussis has been updated. It contains up-to-date information on laboratory testing, clinical presentation, and treatment for pertussis.
Varicella
As of April 30, 2025, Wisconsin has 62 confirmed and probable cases statewide in 2025. Since January 1, 2025, 47 counties have had at least one case. About 52% of the cases had a positive laboratory test. While cases range in age from 4 months to 59 years, the median age of the cases is 10 years. Two individuals have been hospitalized. The majority of cases continue to occur among unvaccinated individuals with about 61% of cases having received no doses of varicella vaccine. No deaths have been reported.
Varicella resources
DHS varicella webpage
CDC varicella webpage
CDC Laboratory testing information
Mumps
As of April 30, 2025, Wisconsin has five. Cases have occurred in two counties in the western part of the state and range in age from 17 to 65 years. One individual has been hospitalized. No deaths have been reported.
Mumps resources
DHS mumps webpage
CDC mumps webpage
DHS mumps fact sheet in English, Spanish, and Hmong
Wisconsin vaccination rate data
The immunization program has vaccination rate dashboards for children and adolescents, influenza, COVID-19, and RSV. These dashboards display vaccination data by location, age group, and demographics. The influenza dashboard also highlights how the CDC’s Social Vulnerability Index (SVI) aligns with influenza vaccination coverage.
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