Health Economic Evaluation of an Influenza Vaccination Program to Prevent Sick Leave in Employees: A Prospective Cohort Study.

OBJECTIVE: To evaluate the cost-effectiveness of an influenza vaccination program (IVP) among employees. METHODS: This health economic evaluation was embedded in a prospective cohort study of a voluntary IVP. Data on incidence, direct, and indirect costs were collected via questionnaires. Bootstrapping and modeling techniques were used to assess uncertainty of the results. RESULTS: In the base-scenario, the IVP was less effective, more expensive and thus, neither cost-effective nor cost-beneficial. When applying a sensitivity analysis using published estimates of IVP effectiveness on the data, the IVP became cost-effective and cost-beneficial. CONCLUSIONS: Like in many evaluations of real-world settings, lack of randomization may have caused selection bias which may explain the surprising results of the main analysis. This indicates the importance of sensitivity analyses and modeling approaches for future studies assessing the cost-effectiveness of IVP in a real-world setting.