Political polarization during COVID-19 was 12 times greater than in past disease outbreaks in terms of vaccine hesitancy, according to a comprehensive new study by Caitlin McMurtry, an assistant professor at the Brown School at Washington University in St. Louis.
In addition, polarization was five times greater around concern about infection, the study found.
The research, published in the American Journal of Public Health, analyzes nearly seven decades of archival survey data, going back to polio in 1954. It highlights how partisanship can shape risk perceptions, compliance with preventive measures and vaccine uptake during health crises.
“Our findings indicate that political polarization during COVID-19 was about five times greater than in any other disease outbreak for which we have public opinion data regarding concern about infection and more than 12 times greater regarding vaccine hesitancy,” McMurtry said.
High levels of polarization continue to linger, suggesting reversal may be difficult.
“Polarization during COVID-19 was considerably more extreme than in past outbreaks, representing a discrete jump in polarization that cannot be explained by gradual partisan separation over time,” she said.
“The findings underscore that political identity goes beyond policy preferences — it also affects how people perceive health threats and act to protect themselves and their communities,” said McMurtry, an expert on health policy and politics. “Even when facing the same epidemiological data, people’s responses often diverge along partisan lines. This has real-world implications for controlling disease spread and ensuring equitable health outcomes.”
The study included 170 polls spanning 13 outbreaks over nearly 70 years. It found that even after adjusting for rising political separation over time, polarization jumped during COVID-19 to unprecedented levels, as it pertains to concern about getting infected with a disease and vaccine hesitancy.
“Low levels of partisan disagreement are not uncommon during times of crisis. But the degree of polarization during and since COVID-19 has eclipsed other disease outbreaks in modern American history, including the anthrax terrorist attacks and the early years of the HIV/AIDS outbreak,” she said.
McMurtry found that polarization during COVID-19 was about 1.1 to 14.9 times higher than should be expected, if pre-pandemic trends stayed constant.
“This indicates past approaches to reducing societal divisions may not be effective,” McMurtry wrote in the paper. “Additional research on strategies to reunify partisans is urgently needed.”
She emphasized the importance of tailoring public health strategies to navigate these divides. “Public health messaging needs to consider the political landscape,” she said. “Strategies that bridge partisan gaps, that depoliticize disease outbreaks, and communicate clearly across different communities are critical for effective outbreak management.”
By analyzing nearly 70 years of data, the broad analysis offers an unprecedented look into how politics and public health have interacted over time.
“This study is not just a historical analysis — it offers actionable insights for current and future public health crises,” McMurtry said. “Understanding how polarization shapes responses can help health officials design more inclusive, effective interventions that can ultimately save lives.”
