Political Polarization During Disease Outbreaks: A Meta-Analysis of Archival Survey Data From Polio to COVID-19

<b>Objectives.</b> To assess how political polarization during COVID-19 compares with that in past disease outbreaks in the United States. <b>Methods.</b> Using random-effects meta-analyses and mixed-effects meta-regressions, we searched the Roper Center for Public Opinion Research and estimated the association between polarization during COVID-19 and during non-COVID-19 disease outbreaks. <b>Results.</b> The study included 170 polls spanning 13 outbreaks over nearly 70 years. Polarization during COVID-19 was 5 and 12 times greater than in past disease outbreaks in terms of concern about infection and vaccine hesitancy, respectively. After we controlled for survey-level characteristics, COVID-19 was associated with 20.23 (95% confidence interval [CI] = 12.30, 28.17) and 25.89 (95% CI = 6.63, 45.16) additional percentage points of polarization regarding concern about infection and vaccine hesitancy, respectively-far higher than historical trends would predict. <b>Conclusions.</b> In terms of concern about infection and vaccine hesitancy, polarization during COVID-19 was substantially higher than in any other disease outbreak in modern American history for which we have relevant data. <b>Public Health Implications.</b> High levels of polarization do not appear endemic to disease outbreaks, suggesting such division may be preventable in the future. (<i>Am J Public Health</i>. 2026;116(1):124-136. https://doi.org/10.2105/AJPH.2025.308226).