Socioeconomic inequality in recommended childhood vaccinations in Germany: evidence from insurance claims and concentration index decomposition.

Abstract

Background: Despite well-established childhood immunization programs in many high-income countries, vaccination series are often delayed or not completed. Gaps in vaccination coverage are more common among children from socioeconomically disadvantaged households, among whom they are associated with higher rates of related hospitalizations. We aimed to assess the extent of these gaps in Germany, as well as the presence of socioeconomic inequality and the factors accounting for it.

Methods: Using health insurance claims data from Techniker Krankenkasse for 2016-2019, we examined vaccination coverage for a comprehensive set of STIKO-recommended childhood vaccinations in six birth-year cohorts (2011-2018; approximately 430,000 children; 2.5 million recommended vaccinations). Coverage was defined as completion of the recommended series with all doses administered within the recommended age window. Socioeconomic inequality was quantified using the Erreygers-corrected concentration index and decomposed into contributions from factors such as parental education and travel time to the treating physician.

Results: Approximately 80% of vaccination series in the sample were complete and administered within the recommended age window. Vaccination coverage showed a small but statistically significant socioeconomic gradient (concentration index = 0.024, 95% confidence interval: 0.023 to 0.025) favoring children from higher socioeconomic households. In the decomposition analysis, provider type accounted for the largest share of this gradient, with lower completion rates and timeliness among children whose outpatient care was mainly delivered by general practitioners compared with pediatricians. Parental education contributed to a lesser extent, and travel time contributed little to the observed inequality.

Conclusions: Childhood vaccination coverage in Germany remains below national targets and shows a small socioeconomic gradient. The gradient appears to be less strongly related to logistical access barriers than to differences in how vaccinations are delivered in outpatient care outside pediatric settings. These provider-type differences in vaccination delivery may therefore be more relevant for narrowing the observed gradient than further reductions in travel time.