The United States has seen a resurgence of measles in the past year. There were 2,280 cases in 2025, with 11% requiring hospitalization and three deaths. We have already seen 2,566 cases this year, and 7% of them were hospitalized. As of August 28, 2026, there have been 92 confirmed and 6 probable cases in the outbreak in Grant, Iowa, and Lafayette Counties. There have been 100 cases in Wisconsin so far in 2026.
Ninety-five percent or more of the population needs to be immunized to prevent the spread of measles. Still, in Wisconsin, only a little over 84.8% of children are vaccinated against measles. While there are currently no measles cases in southeastern Wisconsin, there are active outbreaks in the southwestern part of the state.
It is especially important to note that workplaces can be especially vulnerable, as numerous employees often share spaces. Here are some tips on preparing for a potential exposure in your workplace.
Key facts about measles transmission:
- Ninety-four percent of cases happen in people who are either unvaccinated or their vaccination status is unknown. Non-immune employees have a 90% chance of developing measles if exposed.
- The measles, mumps and rubella (MMR) vaccine remains the most powerful tool to prevent measles and treat exposures.
- The measles virus is spread through airborne transmission and can infect people for up to two hours after the infected person has left the area.
- Illness occurs 7-21 days after exposure (typically in days 10-14).
- Infected persons are contagious from four days before to four days after the rash appears.
Key steps to take if someone in your workplace is infected with measles:
- Identify all employees who shared the same air space with the infected employee or entered the space within two hours after the infected person was there.
- Identify employees’ immune status. Employees are considered immune if at least one of the following is true:
- Have had two doses of MMR at least 28 days apart
- Have laboratory evidence of measles-specific IgG antibody
- Have laboratory evidence of previous measles disease
- Were born before 1957
- Anyone can check their immune status through the Wisconsin Immunization Registry.
- Provide post-exposure prophylaxis with an MMR vaccine to employees who are either unvaccinated or who have an unknown immune status.
- MMR is 83-100% effective but needs to be given within 72 hours of exposure.
- MMR is not given to pregnant women or immunocompromised people; these groups will need immune globulin, a medication that prevents or reduces the severity of an infection.
- Quarantine infected and non-immune employees.
- Contact the Wisconsin Department of Public Health for advice.
- Employees who are infected should not be allowed to work until four days after the onset of the rash.
- For non-immune employees who are exposed:
- If given the MMR vaccine within 72 hours they may not need quarantine but that should be verified with the Wisconsin Department of Public Health.
- If not given the MMR, they should be required to stay home on days 5 to 21 after the exposure.
Froedtert Workforce Health can help with your questions about measles, vaccinations and how you can prepare for and prevent measles. Contact us for more information.
Sources
Measles Cases and Outbreaks | Measles (Rubeola) | CDC
Measles, Mumps, and Rubella (MMR) Vaccination Rate Maps, 2024
Experts: Despite scattered measles cases, Wisconsin could be vulnerable • Wisconsin Examiner
