Social Network Analysis of Information Diffusion and Vaccine Hesitancy in Madagascar: A Community-Based Study

This community-based study examines the critical public health challenge of vaccine hesitancy in Madagascar by analysing the social structures that influence health decision-making. Its objective was to map and analyse interpersonal communication networks to understand how health information and misinformation diffuse and impact vaccination intentions. Conducted between 2023 and 2024, the research employed a sequential, mixed-methods social network analysis (SNA) design within three purposively selected communities exhibiting high hesitancy. Quantitative surveys (n=450) delineated network ties and measured vaccine attitudes, while in-depth qualitative interviews (n=45) with central network actors explored information content and trust dynamics. Ethical approval was obtained from the relevant institutional review board, and informed consent was secured from all participants. Findings revealed that information diffusion was highly clustered. Community health workers occupied central network positions but were sometimes met with distrust. Key hesitancy clusters were reinforced through strong, dense ties within extended family groups, where anecdotal narratives frequently overrode official messaging. Conversely, individuals with bridging ties to multiple social circles demonstrated more moderate views and emerged as potential conduits for credible information. The study concludes that top-down information campaigns are insufficient in these contexts. Its significance lies in demonstrating that effective public health interventions must be network-informed, leveraging trusted bridging individuals and restructuring communication to align with existing social capital. This evidence provides a framework for designing community-embedded strategies to strengthen immunisation programmes in similar settings.