Understanding population-level variability in responses to pathogens over time is important for developing effective health-based messages targeted at ideologically diverse populations. Research from psychological and political sciences suggests that party and elite cues shape how people respond to major threats like climate change. Research on responses to the COVID-19 pandemic suggests similar variability across party identities; however, prior work has methodological limitations. This prospective, longitudinal study of a large probability-based nationally representative U.S. sample assessed in March–April 2020 (N = 6,514) and then 6 months later in September–October 2020 (N = 5,661) demonstrates that COVID-19 fear, perceived COVID-19 death risk, and reported health-protective behaviors became increasingly polarized over the first 6 months of the pandemic. Initial differences between Democrats and Republicans failed to converge over time and became more pronounced. Responses among Republicans were further polarized by support for former President Donald Trump: Trump Republicans initially reported weaker responses to COVID-19 than non-Trump Republicans, and these differences became more pronounced over time. Importantly, political identity and Trump support were not linked to perceived infection risk of a nonpoliticized pathogen, the flu. Finally, political identity and Republican Trump support prospectively predicted COVID-19 vaccine intentions 6 months into the pandemic.

When an individual or group trauma becomes a shared public experience through widespread media coverage (e.g., mass violence, being publicly outed), sharing a social identity with a targeted individual or group of victims may amplify feelings of personal vulnerability. This heightened perceived threat may draw people to engage with trauma-related media because of increased vigilance for self-relevant threats, which can, in turn, amplify distress. We studied this possibility among two U.S. national samples following the 2016 Pulse nightclub massacre in Orlando, FL (N = 4675) and the 2018 Dr. Christine Blasey Ford and Judge Brett Kavanaugh Supreme Court Senate hearings (N = 4894). Participants who shared LGBT or Hispanic identities with Pulse massacre victims reported greater exposure to massacre-related media and acute stress. Participants who shared Dr. Blasey Ford's identities as a victim of interpersonal violence and a Democrat reported more hearings-related media exposure and acute stress. Indirect effects of shared single identity on acute stress through self-reported event-related media exposure emerged in both studies. Results for sharing dual identities with victims were mixed. These findings have implications for media use and public health.