Data Show Politics Has Become a Powerful Driver of Vaccine Hesitancy

As the COVID-19 vaccine campaign has proceeded and slowed, a pattern has emerged across the country: States where greater shares of people voted for former President Donald Trump tend to have the lowest vaccination rates, making their residents more vulnerable to the coronavirus and its variants.

The pattern holds true within Colorado, too. Counties that turned out strongest for Trump had lower vaccination rates as of June 24, 2021.

In Mesa County, Trump took nearly two-thirds of the vote, and just over a third of residents are vaccinated. In Eagle County, on the other hand, the numbers are essentially reversed: Trump got a third of the vote and more than 60% of residents are vaccinated.

The correlation between Trump votes and low COVID-19 vaccination rates is remarkably strong. Correlation is calculated on a scale of -1 to 1, where -1 means the two variables are perfectly negatively correlated (a low level of variable A is connected to a high level of variable B) and +1 means they are perfectly positively correlated (a high level of variable A is connected to a high level of variable B). The Trump vote has a -0.82 correlation to the vaccination rate of Colorado counties, meaning the more residents who voted for Trump in a county, the less likely its residents are to be vaccinated.

Emily Johnson, CHI’s Director of Policy Analysis, ran the numbers last Friday in preparation for this blog post. She said values of 0.8 are uncommon in the social sciences.

University of Denver Professor Seth Masket used the same terminology in a Denver Post column that compared vaccination rates and Trump votes among the states. “We almost never see this high a correlation between variables in the social sciences,” Masket wrote.

CHI also compared COVID-19 vaccination rates to median household income and the percentage of the adult population with less than a high school degree in Colorado’s counties — other factors that we hypothesized might affect vaccination rates. The correlations for income and lower educational attainment were 0.53 (lower median household incomes were correlated with lower vaccination rates) and -0.45 (larger numbers of people lacking a high school degree were correlated with lower vaccination rates), respectively. That means those variables were also tied to COVID-19 vaccination rates — but the correlation was much less strong than a county’s 2020 election results.

You may have heard the phrase “correlation doesn’t equal causation.” It’s a reminder that the fact that two things appear to be statistically connected doesn’t mean one necessarily caused the other. A range of community and personal factors — anything from population density to access to vaccines to individual health status — may affect whether a person is vaccinated.

But there’s clearly something worth paying attention to in this startlingly strong link between presidential politics and vaccine hesitancy — which arose with dizzying speed and marks a break with historical trends. The Colorado communities where schools have high rates of students who have been opted out of childhood vaccines are all over the map politically. The communities where high rates of people don’t have a COVID-19 vaccine are not.

Trump’s norm-breaking presidency has a lot to do with this shift. He downplayed COVID-19, even after catching a serious case himself, rarely wore a mask, got his vaccination in private, and tolerated conspiracy theories about the virus and vaccines. Even now that he has left office, the consequences are ongoing — and appear to have become a major impediment to vaccinating enough people to prevent another wave of infections in the United States. Public health workers — and all of us — will have to contend with this dynamic before we can put COVID-19 behind us for good.

What do we do with this information? Communication is part of the answer; we addressed ways to reverse vaccine hesitancy among Republicans (who do not overlap entirely with Trump voters) in a previous post. And as we look forward, there may be lessons to learn from this pandemic about how to identify and address the ideological drivers of vaccine hesitancy before the patterns become so entrenched — and before so many Coloradans let politics drive their health decisions.

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