[Once vaccinated, always vaccinated? A claims data analysis on repeated influenza vaccinations among individuals aged...

The Standing Committee on Vaccination recommends the seasonal influenza vaccination as a standard vaccination for individuals aged ≥ 60 years and as an indication vaccination independent of age. Empirical data on repeated vaccination are not available for Germany. The aim of this study was therefore to investigate the frequency and influencing factors of repeated vaccinations.

We conducted a longitudinal retrospective observational study with claims data from ≥ 60‑year-olds insured with the statutory health insurance AOK Plus in Thuringia between 2012 and 2018. The number of seasons with influenza vaccination was described and the association with various individual characteristics was analysed in a regression model.

Included were 103,163 individuals with at least one influenza vaccination in the 2014/2015 season, of whom 75.3% had been vaccinated in ≥ 6 of 7 seasons. We found repeated vaccinations more frequently among nursing home residents (rate ratio (RR) 1.27), individuals with increased health risk due to underlying diseases (RR 1.21) and higher age groups (vs. 60-69 years: RR 1.17-1.25). With each additional year of participating in a disease management program, the number of vaccinations increased (RR 1.03). Women (RR 0.91), individuals with nursing care level 1 (vs. no nursing care level: RR 0.90) and people with a comorbidity (vs. no comorbidity: RR 0.97) were less likely to receive repeated vaccinations.

A large proportion of individuals aged ≥ 60 years who have been vaccinated against influenza once is likely to repeatedly receive vaccinations. In accordance with vaccination recommendations, nursing home residents and in particular individuals with an increased health risk are vaccinated repeatedly. General practitioners play a central role: non-acute patient contacts should be used to offer vaccinations, especially to women and individuals in need of care who are living at home.