Republicans are dying at a higher rate from COVID-19 than Democrats, new research suggests.

A working paper from the Massachusetts-based National Bureau of Economic Research by Yale University researchers estimates “substantially higher excess death rates for registered Republicans when compared to registered Democrats” in Ohio and Florida from 2018 to 2021.

Excess deaths are defined as those above what would normally be expected and have been used to measure the true toll of COVID-19 since the number includes those who died indirectly from the virus, for example, because the pandemic kept them from accessing needed health care.

Between March 2020, when the COVID-19 pandemic began, and December 2021, researchers said average excess death rates were 76% higher among Republicans than Democrats in the two states studied. But that gap increased to a 153% difference after April 2021, when all adults were eligible for COVID-19 vaccines in Florida and Ohio.

And although data on the political affiliation of those vaccinated was not available, researchers said differences in Republican and Democratic attitudes toward the shots as well as other efforts against COVID-19 have been established in other studies.

So, they concluded the “sharp contrast in the excess death rate gap before and after vaccines were available suggests that vaccine take-up likely played an important role,” using county-level vaccination rates found “evidence that vaccination contributes to explaining differences in excess deaths by political party affiliation.”

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It’s not clear what the study means for other states, including those like Utah that are dominated by the GOP.

“The study examined data from Ohio and Florida, so we don’t know exactly how well it might generalize to other states in different regions,” said Chris Karpowitz, co-director of Brigham Young University’s Center for the Study of Elections and Democracy.

“It does indicate, however, that partisan differences in rhetoric about vaccination and about the pandemic more generally can have very real life and death consequences,” the political science professor told the Deseret News, noting the partisan gap in death rates is concentrated in places where vaccination rates are low.

That means “anything that elected leaders can do to increase vaccine uptake more generally will likely reduce partisan differences,” Karpowitz said. “Studies like this also prompt questions about whether Americans are paying enough attention to staying up to date with their vaccinations, including with the new bivalent booster.

Utah’s COVID-19 vaccinations lag behind the U.S. rate, with 64.3% of all Utahns completing the initial series of shots compared to 68% nationwide. But less than 31% have gotten a booster shot, while just under 49% nationwide have had a first booster shot.

As of Monday, more than 116,000 Utahns had received the new, updated booster shot, called bivalent because it targets currently circulating COVID-19 omicron subvariants, as well as the original version of the virus. Nationwide, the Centers for Disease Control and Prevention said 11.5 million people had gotten the shot as of Thursday.

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The authors of the new study said vaccine hesitancy among Republicans may be the biggest reason for the partisan gap in deaths.

“In counties where a large share of the population is getting vaccinated, we see a much smaller gap between Republicans and Democrats,” Jacob Wallace, an assistant professor of health policy at the Yale School of Public Health, told NBC News.

“We really don’t see a big divide until after vaccines became widely available in our two states,” Wallace said.

A research letter posted online in The Lancet Infectious Diseases in August found Massachusetts, a Democratic stronghold with one of the nation’s highest COVID-19 vaccination rates, had a big drop in excess virus-related deaths following the omicron surge earlier this year.

NBC pointed out that another, broader study by researchers in Maryland and California, published in Health Affairs in June, came to a different conclusion about the impact of vaccine hesitancy on differing death rates between Republicans and Democrats.

The June study said vaccine uptake explained only 10% of the partisan gap in deaths because their “findings suggest that county-level voting behavior may act as a proxy for compliance with and support of public health measures that would protect residents from COVID-19,” such as masking and social distancing

“Vaccination does play a role in the difference that we’ve observed in excess mortality between red and blue places, but it is not the whole story,” Neil Jay Sehgal, an author of that study and an assistant professor of health policy and management at the University of Maryland School of Public Health, told NBC News.

“When you have less transmission, you have fewer cases and you have less mortality. And you have less transmission in general by instituting protective policies like mask requirements when we had them, or capacity limits in businesses,” he said.

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Sehgal acknowledged that what the new research found may be the case in the two states studied.

“It may very well be that in Ohio and Florida, because of the nature of Ohioans and Floridians, vaccine uptake may have played a greater role than [in] the country at large,” Sehgal told NBC.

Neither researcher said their studies should be seen as blaming Republicans for COVID-19 deaths, according to the network.

“This is not saying: If Republicans were in fact Democrats, they’d be less likely to die,” Wallace told NBC. But he also said that when it comes to the overall consequences of vaccine hesitancy, “we’re talking about a lot of preventable death and morbidity.”