Vaccination gaps in decentralized emergency response: understanding immunization barriers among volunteer firefighters. A cross-sectional mixed methods study

Introduction: Volunteer firefighters are crucial for decentralized emergency response systems but operate outside standardized occupational health frameworks. Despite elevated exposure to biological hazards, systematic data on vaccination knowledge, immunization status, and preventive health engagement in this population are limited. To better understand the determinants of their preventive health engagement, and to inform strategies that strengthen operational readiness and public health resilience, this study examined vaccination behavior among German volunteer firefighters and identified determinants of immunization uptake. Methods: Between April 2025 and August 2025, semi-structured interviews were conducted with 150 active volunteer firefighters. Data were analyzed using inductive qualitative content analysis, following Mayring's framework. Vaccination status, evaluation of vaccination, and willingness to undergo medical surveillance were assessed. K-means cluster analysis identified behavioral typologies, and Spearman's correlations examined the associations between risk perception, social integration, and vaccination behavior. Results: Approximately one-third of the participants could not confirm their current immunization status. The most common vaccinations recorded among the 150 firefighters were tetanus (n = 110) and hepatitis B (n = 100). Three distinct behavioral clusters emerged: health-engaged prevention-oriented individuals (predominantly healthcare workers), vaccine-supportive but surveillance-resistant firefighters (craftsmen/trading backgrounds), and vaccine-ambivalent personnel open to alternative prevention (logistics/technical fields). Hazard perception was weakly correlated with vaccination status (ρ = +0.300, p = 0.035). Social proximity correlated positively with vaccination willingness (ρ = +0.33, p = 0.037) and negatively with hazard perception (ρ = -0.43, p = 0.024). Vaccination rates varied by occupation, ranging from 100% in IT/technical professionals, to 66.7% in healthcare workers, and 50 % craftsmen/trading workers. Discussion: Substantial vaccination knowledge gaps, incomplete documentation, and heterogeneous behavioral patterns shaped by professional background and institutional trust characterized the population surveyed. Effective interventions require differentiated strategies that address structural barriers, transparent communication, integration with valued occupational health surveillance, and recognition of distinct motivational profiles across volunteer firefighter subgroups.