Investigation of factors affecting vaccine acceptance with regularized structural equation modeling

Vaccine hesitancy is a complex and multidimensional phenomenon, as emphasized by the World Health Organization. Both rational and irrational dynamics play a role in individuals' decision-making processes, which in turn influence vaccine acceptance. This study investigates the factors affecting vaccine acceptance. Healthcare workers, due to their direct contact with patients, represent a high-risk group and were selected as the study population. In the literature, the use of multivariate models to examine the determinants of vaccine hesitancy remains limited. This study aims to contribute both theoretically and methodologically by analyzing the psychosocial and cognitive factors influencing healthcare workers' attitudes toward vaccine acceptance using the Penalized Structural Equation Model (RegSEM). The study population consists of healthcare professionals affiliated with the Adana Provincial Health Directorate. Data were collected from 554 participants through simple random sampling, using a sociodemographic form and six attitude scales: Vaccine Hesitancy Scale, General Conspiracy Beliefs Scale, Belief in Science Scale, Social Media Use Scale, Distrust in Health Systems Scale, and Information Literacy Scale. During model construction, only the RegSEM-LASSO method was applied. Weak associations were eliminated, preserving only strong pathways. Model fit was assessed using CFI, RMSEA, and SRMR indices, clarifying the structural relationships between conspiracy beliefs, system trust, and vaccine hesitancy. The findings indicate that RegSEM improves both model simplicity and interpretability compared to traditional structural equation models. The results suggest that strategies reinforcing institutional trust—beyond individual knowledge levels—may be more effective in promoting vaccine acceptance. This study offers guiding insights for both academic research and practical public health communication. Keywords: Vaccine hesitancy, conspiracy theories, health system distrust, RegSEM, LASSO.