Moral Foundations, Ideological Divide, and Public Engagement with U.S. Government Agencies’ COVID-19 Vaccine Communication on Social Media

Guided by moral foundation theory, this study examined how moral framing interacted with local constituents’ ideological leaning to affect public engagement outcomes of government agencies’ COVID-19 vaccine communication on Facebook. We analyzed a dataset of over 5,000 U.S. government agencies’ Facebook posts on COVID-19 vaccines in 2021 (N = 70,671), assessed their use of moral language using a newly developed computational method, and examined how political divide manifests itself at the collective level. Findings from both fixed and random effects models suggest that: 1) the use of moral language is positively associated with public engagement outcomes on government agencies’ social media accounts; 2) five types of moral foundations have distinct effects on three types of public engagement (affective, cognitive, and retransmission); 3) moral foundations and local politics interact to affect public engagement, in that followers of government agencies in liberal states/counties prefer messages emphasizing the care/harm and fairness/cheating dimensions while those in conservative states/counties prefer the loyalty/betrayal dimension. The study demonstrates how a strategic employment of moral language can contribute to public engagement of government agencies’ mass communication campaigns.