OBJECTIVES: To assess cost-effectiveness of a vaccine that would protect against both Lyme Borreliosis (LB) and tick-borne encephalitis (TBE) in a highly endemic setting in Slovenia.

METHODS: A Markov model was developed to estimate cost-effectiveness of a potential single combination vaccine against LB and TBE from the societal perspective. The model expressed time in annual cycles, followed a target population through their lifetime, and applied an annual discounting of 3%. A target population entered the model in a susceptible state, with time dependent probabilities to acquire LB/TBE infections and their acute manifestations. Disease manifestations were either resolved within one cycle, or a patient developed LB/TBE sequalae. The vaccination, which consisted of initial immunization and one revaccination, reduced the probability of contracting LB/TBE infection, thus affecting costs and utilities. Estimates of LB/TBE direct and indirect costs, and data on natural course of LB/TBE were obtained from local Slovenian databases. Effectiveness of the potential combined LB/TBE vaccine was derived from the studies on existing TBE and LB vaccines, while utility estimates were collected from various literature sources.

RESULTS: A potential combined LB/TBE vaccine was predicted to have an incremental cost of €771,305 per 10,000 vaccinated persons, an incremental utility of 16.74QALYs and a base-case incremental cost-effectiveness ratio (ICER) of €46,061/QALY. Vaccine cost, effectiveness and discount rates were identified as the most influential model parameters. A vaccine price of €9.13 would lead to cost savings and pharmacoeconomic dominance of the vaccination strategy.

CONCLUSIONS: The base-case ICER was below commonly accepted thresholds of cost-effectiveness (3xGDP/capita=€52,500/QALY in Slovenia), indicating that a combined LB/TBE vaccine might be a cost-effective option in Slovenia. This analysis represents a rare example of cost-effectiveness assessment prior market authorisation. Although some key parameters were unknown, our model sets up a tool to analyze pharmacoeconomic criteria that can help development of a cost-effective health technology.