Online Health Misinformation Susceptibility Increases Health Risk Behaviors and Vaccine Hesitancy: Evidence from Greece

Background: Health-related misinformation is a pervasive phenomenon that expanded substantially during the COVID-19 pandemic, particularly regarding concerns about vaccine safety and effectiveness. Objective: To investigate the impact of online health misinformation susceptibility on health behaviors and vaccine hesitancy. Methods: A cross-sectional study was conducted in Greece, with data collected via an online survey during September 2025. We used the Health-Related Online Misinformation Susceptibility Scale to measure online health misinformation susceptibility. Health Behavior Inventory – Short Form was used to measure health behaviors, while Vaccine Hesitancy Scale (VHS) was used to measure participants’ hesitancy towards vaccination. We performed multivariable analysis to identify the independent effect of health misinformation after adjustment for several confounders. Results: Multivariable linear regression analysis showed a positive association between online health misinformation susceptibility and diet score (adjusted coefficient beta = 0.026, 95% confidence interval [CI] = 0.006 to 0.046, p = 0.010) and anger and stress score (adjusted coefficient beta = 0.033, 95% CI = 0.013 to 0.052, p = 0.001). After adjustment for confounders, we found a positive association between online health misinformation susceptibility and score on the factors “lack of confidence” (adjusted coefficient beta = 0.016, 95% CI = 0.005 to 0.028, p = 0.006) and “risk perception” (adjusted coefficient beta = 0.023, 95% CI = 0.010 to 0.036, p = 0.001). Conclusion: Our findings suggest that higher susceptibility to online health misinformation is linked to poorer health behaviors and greater vaccine hesitancy.