Comunicación política, institucional y medios de comunicación en tiempo de pandemia. Análisis del diálogo sobre vacunas en cinco países iberoamericanos / Political and institutional communication and the media in times of pandemic. Analysis of the di

This study examines how political, institutional, and media actors communicated about COVID-19 vaccines on Twitter in five Ibero-American countries: Argentina, Brazil, Chile, Spain, and Mexico. The research analyses 68,822 tweets from 84 verified accounts, including those of presidents, health authorities, and major media outlets. Findings reveal that mass media and health institutions were the most prolific sources, yet tweets from personal accounts—especially those of political leaders—achieved higher levels of engagement. While the overall audience interaction was mostly positive in the form of likes and retweets, direct replies often expressed scepticism, particularly towards political figures. The hybrid media system has blurred traditional boundaries of authority and credibility, demonstrating that institutional actors and media share similar capacities for message dissemination, but politicians experience higher levels of both support and polarisation. This study contributes to understanding digital political communication, public trust in institutional messaging, and the dynamics of health information dissemination during crises. It underscores the relevance of hybrid media logics, sentiment analysis, and the need for communication strategies that enhance credibility and democratic engagement.