PIN105 - THE PUBLIC HEALTH IMPACT OF TICK-BORNE ENCEPHALITIS VACCINATION ON THE SLOVENIAN ADULT POPULATION

Abstract

Despite Slovenia having one of the highest Tick-Borne Encephalitis (TBE) incidence rates in Europe, TBE vaccination coverage in Slovenia remains low in the general population. This study evaluates the potential public health impact of implementing an additional TBE universal mass vaccination (UMV) campaign for Slovenian adults of 45-50 years of age (YOA). A lifetime Markov cohort model was developed to reproduce the natural history of TBE infection in Europe. The study population of Slovenian adults, 45-50 YOA (total cohort size: 177,353), was followed using a 1-year cycle length, during which the probability of infection and moving to a specific health state was determined by age- and gender-specific incidence rates (corrected for underreporting) and specific state-to-state transition probabilities. It was assumed that the vaccination coverage was 50% and that the vaccinated population would be fully compliant with the conventional TBE vaccination schedule. Following the outcomes of recently published literature on the sustained immune response after TBE vaccination, an extension of the booster time-interval was explored from 3 or 5 years to 10 years irrespective of age. Implementing a UMV campaign for Slovenian adults of 45-50 YOA would reduce the total number of TBE cases by 761 cases (23.4%), of primary phase symptoms by 282 cases (23.4%) as well as of secondary phase symptoms by 19 cases (22.5%). Consequently, 332 to 498 days of hospitalization could be averted. An extension of the booster time-interval would prevent 52 cases (6.8%) less while the amount of secondary phase symptoms would increase by 1 case (5.2%). Nevertheless, the total amount of required booster doses would be reduced by 230,867 doses (39.5%). Implementing a TBE UMV campaign in the 45-50 YOA adult Slovenian population would result in a significant public health impact irrespective of an extended booster time-interval for the TBE-vaccine schedule.