Tick-borne encephalitis (TBE) vaccine uptake in Sweden remains limited (see, for example, Snapshot Week 13/2025), and vaccine effectiveness (VE) has not yet been systematically analyzed in this Nordic country. To address this gap, a study was conducted to estimate vaccine uptake, assess VE, and evaluate its public health impact.
Between 2018 and 2022, a total of 2,015 TBE cases were reported in Sweden, corresponding to an annual incidence of 3.9 per 100,000 population. The highest incidence—8.1 per 100,000—was observed in the Middle East region of Sweden. Vaccination history was available for 1,890 of these cases, of whom 82.8% were unvaccinated and 17.2% had received at least one dose. Among the vaccinated, 44.8% were only partially vaccinated, while 25.1% had been vaccinated according to the recommended schedule.
The effectiveness of a complete three-dose vaccination schedule was estimated at 89.0%. When stratified by age, VE was 86.0% in children aged 1–15 years, 93.8% in adults aged 16–49 years, 84.1% in those aged 50–59 years, and 83.4% in individuals aged 60 years and older. Slight variations in VE were also noted across different geographic regions of Sweden.
Based on the observed VE of 89.0%, the authors estimated that administering three vaccine doses to the entire Swedish population could have prevented approximately 2,688 TBE cases during the study period.
The study confirmed the high effectiveness of TBE vaccination, consistent with findings from other European countries, and demonstrated its potential to prevent cases that often result in hospitalization. To reduce the burden of TBE in Sweden, enhanced efforts to improve vaccine uptake are urgently needed.