Wisconsin Health Officials Concerned About Measles Coming to Wisconsin

Wednesday, March 5th, 2025 -- 12:00 PM

(Richelle Wilson, Wisconsin Public Radio) A recent measles outbreak in Texas, which resulted in one child’s death and at least 20 hospitalizations, has public health officials worried that the highly-contagious disease could come to Wisconsin.

According to Richelle Wilson with Wisconsin Public Radio, Wisconsin has the second-lowest measles vaccination rate for children nationwide, according to state health data.

About 85 percent of Wisconsin kindergarteners have both doses of the measles, mumps and rubella vaccine, commonly called the MMR vaccine. In some parts of the state, the rate is much lower, coming in below 50 percent.

That’s a problem because of how contagious measles is. Malia Jones is a public health researcher and assistant professor in the Department of Community and Environmental Sociology at the University of Wisconsin-Madison.

She told WPR’s “Wisconsin Today” that even an 85 percent vaccination rate, which might sound high, is not enough when it comes to measles. “We need really, really high vaccine coverage in order to protect a community from a measles outbreak,” Jones said. “It is the most infectious disease on Earth. Nearly everyone who is exposed to measles and has not been vaccinated will get it.”

“For measles, we need something like 95 to 98 percent of all people to be vaccinated in order to protect us from an outbreak,” she continued. In Wisconsin, “we’re well below that in many, many settings.”

In public health, infectious diseases have what’s called a “reproductive number” that represents how many people one sick person will infect on average.

For context, the original strain of the virus that causes COVID-19 had a reproductive number of three. Measles has a reproductive number between 12 and 18, which surpasses diseases such as chickenpox and mumps, too.

“That means for every infection, it can spread to 12 to 18 more people who are unvaccinated,” Jones said. “And if you think about a school setting … it’s very easy to get 12 or 18 kids in a room, and if a lot of them are unvaccinated, you’re going to see very rapid spread.”

“I would even go so far as to say that it’s just a matter of time before Wisconsin has an outbreak,” she added.

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