Structural barriers drive the intention-action gap in hepatitis B prevention among migrants in Shandong Province, China: a triangulated study of serological, spatial, and behavioral data

Background Hepatitis B virus (HBV) infection remains a major public health challenge in China. Migrant workers constitute a highly vulnerable population due to high geographic mobility and occupational vulnerability. Despite public health education efforts, a notable intention-action gap disrupts the HBV care cascade. This study integrates serological, spatial, and behavioral data to investigate whether this gap is primarily driven by cognitive deficits or interrupted by underlying structural barriers. Methods A triangulated cross-sectional study was conducted in Yantai, China, involving structured questionnaire surveys (N = 1,184) and serological testing (N = 2,364). The spatial distribution of regional anti-HBs positive rates was mapped using Geographic Information Systems (GIS). An adapted Health Belief Model was tested using Structural Equation Modeling (SEM) with a Robust Maximum Likelihood estimator to evaluate the disruptive effects of objective structural constraints—specifically, time poverty, economic constraints, and systemic lack of medical insurance. Results The serologically confirmed anti-HBs positive rate was 51.10% (1,208/2,364), substantially lower than the 70% threshold recommended by the World Health Organization. Spatial analysis revealed significant geographic heterogeneity (χ² = 74.38, P < 0.001), with higher immunity concentrated in large-scale industrial belts (67.33%) and lower immunity clustered in dispersed service-sector districts (36.81%). SEM results indicated that while external cues strongly predicted HBV knowledge (β = 0.894), knowledge had only a marginal effect on preventive intention (β = 0.192). Preventive intention significantly predicted actual behavior (β = 0.655). However, this motivational process was severely undermined by structural barriers, predominantly time poverty (β = -0.563, P < 0.001), followed by economic constraints (β = -0.278, P < 0.001) and lack of medical insurance (β = -0.056, P = 0.030). Conclusions The intention-action gap in HBV prevention among migrant workers is primarily driven by socioeconomic structural barriers—most notably time poverty—while basic HBV knowledge remains a foundational but insufficient condition for preventive action. Achieving the goal of viral hepatitis elimination requires a shift from individual cognitive persuasion to structural interventions, emphasizing workplace-based service delivery, spatially targeted resource allocation, and insurance reforms to alleviate out-of-pocket and opportunity costs.