Abstract
BACKGROUND: The aims of the study were to determine the influenza vaccination coverage among individuals aged 60 and older, examine spatial variations, and identify spatial clusters as well as regional risk factors for low vaccination coverage. METHODS: The study was based on nationwide outpatient claims data from 2022 and 2023. The study population consisted of 22,303,411 individuals with statutory health insurance aged 60 and older. The influenza vaccination coverage was calculated as the proportion of vaccinated individuals during the 2022/23 season among all persons with Statutory Health Insurance (SHI) who had contact with SHI-authorized physicians in 2022. Global spatial autocorrelation, local spatial clusters, and regional risk factors for low vaccination coverage were examined using global and local Moran's I as well as geographically weighted regression. RESULTS: The nationwide influenza vaccination coverage was 37%, with district-level variations ranging from 10% to 61%. The global autocorrelation was 0.87 (global Moran's I, p < 0.0001). Two strongly pronounced local clusters were identified. A large spatial cluster with relatively high vaccination coverage spanned across all eastern federal states as well as districts in southeastern Lower Saxony, Schleswig-Holstein, and Hamburg. Another cluster with relatively low vaccination coverage encompassed almost all districts in southern Germany. The risk factors for low vaccination coverage included residence in western Germany and in sparsely populated rural districts. The density of general practitioners showed a positive correlation with vaccination coverage. The relationships between vaccination coverage and explanatory variables varied regionally. DISCUSSION: The identification of spatial clusters and regional risk factors for low vaccination coverage can serve as a basis for regionally tailored intervention measures to improve vaccine uptake.