why do people share vaccine misinformation on social media? a psychological and social analysis

Background: misinformation sharing on social media is a global concern with varying influencing factors across different societies. understanding these factors is crucial to designing effective interventions, particularly in non-western contexts, such as iran. methods: this cross-sectional quantitative study used a crowdsourcing survey with chain referral sampling to recruit 600 adult media users in hamadan, iran (57.8% women and 42.2% men). a structured questionnaire adapted from validated scales assessed psychological, social, and cognitive factors. partial least squares structural equation modeling was applied to analyze data with significance set at p<0.05. results: key predictors of sharing intention included trust in government (β=0.147, p<0.001), accuracy assessment (β=-0.539, p<0.001), fear of missing out (β=0.110, p=0.003), media dependency (β=0.080, p=0.023), social comparison (β=-0.089, p=0.006), and media fatigue (β=-0.124, p=0.001). media literacy did not moderate these relationships. among demographic variables, only education level showed a significant effect (β=-0.12, p<0.01). the results of structural equation modeling indicated good model fit: χ²=112.5, standardized root mean square residual=0.07 (values<0.08 suggest good fit), and normed fit index=0.90 (values>0.90 are acceptable). conclusion: our study revealed unique cultural drivers of health misinformation sharing in iran, highlighting the critical roles of institutional trust and accuracy assessment. the findings emphasize the need for context-specific strategies in developing interventions to combat misinformation.