Politicizing prevention: Vaccine polarization, misinformation, and institutional trust in Brazil

Brazil once had some of the highest vaccination rates in the world, yet coverage has declined sharply since 2015 despite universal and free access. Why has hesitancy increased in a system historically marked by strong immunization capacity and broad political support? Drawing on an original survey and in-depth interviews with health workers and municipal officials, this article argues that vaccine hesitancy in Brazil reflects the interaction of misinformation, partisan alignment, and fragmented institutional trust in a decentralized democracy. First, misinformation surrounding COVID-19 generated spillover effects that reduced confidence in routine vaccines. Second, credibility cues matter: misinformation attributed to physicians is more persuasive than identical claims from political, religious, or interpersonal sources. Third, polarization is directional: Bolsonaro supporters are significantly more likely to express hesitancy, while support for pro-vaccine leaders does not produce equivalent consolidation. In polarized and decentralized contexts, trust in vaccine-skeptical elites can amplify rather than mitigate resistance to preventive health policy.