Geographical disparities in vaccination could lead to COVID ‘hotspots’ where outbreaks are more likely

MADISON, Wis. – While Dane County is among the best in the country when it comes to vaccination, it doesn’t look the same all over the state.

That stands out to Ajay Sethi, associate professor of population health sciences at the University of Wisconsin – Madison, as he looks at county level data.

“There are some counties where only a quarter of residents have had one shot or both shots,” Sethi said. “Others are on the high end, over 60%.”

That includes Dane County, where 65.6% of people have gotten at least one shot, according to state data. That number ranges throughout the state, sitting at 45.7% in Rock County and going as low as 26.2% in Taylor County.

If that disparity continues, Sethi said we could start to see impacts.

“It means that over time, we’ll see a mosaic where cases are occurring and where hot spots are,” Sethi said. “Some of it will be defined by county and some of it will be defined by the gathering of people who are generally unvaccinated.”

That could mean geographical pockets close or at herd immunity and others left vulnerable.

“Let’s say my neighborhood, everyone in my neighborhood doesn’t want to get vaccinated, then there’s a big chance there may be a sudden outbreak in this community that may hit the vulnerable population,” said UW-Madison Professor Oguz Alagoz, who models infectious diseases. “This pandemic is not over yet.”

There are vaccination differences within counties, too, including Dane.

“We’re seeing some disparities among rural populations and some areas sprinkled throughout the county,” said Rebecca LeBeau, public health specialist at Public Health Madison & Dane County.

LeBeau pointed to areas including Marshall, York and Edgerton as having relatively low rates, compared to places like Verona where they’re higher.

“It’s a starting point with that data to point us toward where there might be some of those barriers, and then we really rely on community connections to be able to understand what those barriers are and how to address them,” she said, adding that anyone interested in a clinic or community Q&A can email

Dane County Vaccination Rates

Source: PHMDC
The darker blue the area, the lower the vaccination rate.

The Town of Dane also had a lower vaccination rate compared to other municipalities. According to the latest PHMDC data snapshot, the Town of Dane had a significantly higher rate of COVID-19 cases in recent weeks.

While there are other factors at play such as how densely populated an area is, data experts are keeping an eye on whether lower vaccination rates will correlate with higher COVID-19 cases.

“If the rates are very different, let’s say Dane County is around 80%, and then another county let’s say is around 40%, then I guess in two months then we could really see the real effect,” Alagoz said.

Impact on herd immunity

As long as there are outbreaks, Sethi said we haven’t hit true herd immunity, and he doesn’t expect to reach that any time soon.

“But those outbreaks can become very rare,” he said. “They can prompt vaccine promotion in those places where outbreaks are occurring.”

Instead of getting caught up with herd immunity as the only goal, Sethi stressed the importance of vaccination in controlling the virus.

“First and foremost, if you’re vaccinated, you can feel confident you’re protected against severe COVID,” he said. “I think people should think of (herd immunity) as a destination that would be great to have, but we can feel a lot safer before declaring herd immunity as a state or in a county or community. When case rates are really low, we can feel very safe and feel like life is returning back to normal.”

High rates of vaccination among older adults will also make a difference, already resulting in fewer hospitalizations.

“Even in Dane County, we’re seeing a really highly vaccinated population of 65+ year-olds, we’re seeing cases drop very quickly and have really trickled down to very few cases in that age group,” LeBeau said. “We want to see that for everyone.”

Predicting the spread of COVID is tough, especially with variants in play, but experts know how to stop it.

“The vaccine is the best tool we have,” LeBeau said.

It’s a tool that’s working better than many could have hoped. Alagoz said he’s happy to see the vaccines are working so well, not only proving themselves in clinical trials but in real world settings.

“Even with variants, vaccinations seem to be working,” he said.

It’s a breath of fresh air for Alagoz, who has talked with News 3 Now in the past about COVID-19 data when things weren’t always so hopeful.

“It’s just more fun,” Alagoz said. “It’s really fun to speak these days because finally we have a lot of good news, positive news, and I am cautiously optimistic.”