RALEIGH, N.C. (WNCN) — The correlation between the percentage of votes for Donald Trump for president in 2020 and the vaccination rate in that area is not as strong across North Carolina’s counties as it is nationally, an expert says.

A study by Dr. Michael Bitzer, a political science professor at Catawba College, finds a connection between vaccination rates and the share of Trump voters in a county but says there’s more of a correlation between those rates and another variable — the county’s per capita income.

The connection is also stronger at the national level than the county level, he said.

“In a county, there is a relationship, but it’s not as strong as what we’re finding nationally,” Bitzer said.

Bitzer compared the state’s vaccination data by county from June 29 to the voting percentages and did find a correlation.

This scatter plot shows the correlation between North Carolina’s 100 counties in terms of their vaccination percentage and the share of voters who chose Republican Donald Trump in the 2020 presidential election. (Source: Dr. Michael Bitzer, oldnorthstatepolitics.com.)

“Not surprisingly, as a Trump performance vote goes up, the vaccination rate goes down,” he said. “That’s not surprising, because so many Republicans have questions the vaccine, have questioned whether they need to get vaccinated.”

But that correlation is relatively weak; it explains only about 15 percent of a county’s vaccination percentage, he found.

A stronger one — roughly 42 percent — was found between those rates and the income level of a county, he found.

This scatter plot shows the correlation between North Carolina’s 100 counties in terms of their vaccination percentage and the county’s per capita income level. (Source: Dr. Michael Bitzer, oldnorthstatepolitics.com.)

“Right now the per capita income seems to be driving a lot of the vaccination rate,” Bitzer said. “So as a county’s per capita income increases, so too, does the vaccination rate.”

Other variables seem to have lesser effects, including a county’s demographic breakdown. Counties with higher non-White populations tend to have more people taking a “wait-and-see” approach, he said.

His findings did cast some doubt on one piece of conventional thinking — that urban counties are generally doing better than rural ones. Part of it might be because rural counties tend to have a higher percentage of prisons, and they could affect that county’s vaccination numbers, Bitzer wrote.

“We can’t say for sure if the presence of an urban county has an impact on vaccination,” he said. “But what was interesting was the rural variable was statistically significant. So we can say it does have an impact, but it was positive — meaning that, if you were in a rural county compared to a suburban county, that rate was actually going up.”

Bitzer says he wants policy makers and those in public health to be aware of the various reasons those numbers are low in some places.

“I hope that this is kind of the beginning of a conversation, particularly for policymakers and public health officials to think about — ‘OK, these factors play into it, what could be some other factors?’” Bitzer said, adding that his model only predicts about 60 percent of the vaccination rate. 

“That means that there are other variables, other factors out there that we should think about for the 100 counties, to help us get a better handle on why people are vaccinating or perhaps why a county’s rate is lower,” he said.

CBS 17’s Joedy McCreary has been tracking COVID-19 figures since March 2020, compiling data from federal, state, and local sources to deliver a clear snapshot of what the coronavirus situation looks like now and what it could look like in the future.