Burden of seasonal influenza in the Swiss adult population during the 2016/2017–2018/2019 influenza seasons

Background
Evidence on the burden of seasonal influenza in Switzerland is scarce, yet it is critical for the design of effective prevention and control measures. The objective of this study was to assess influenza-related resource utilization, health care expenditures and quality-adjusted life-years (QALYs) lost in Switzerland across the 2016/2017–2018/2019 influenza seasons.
Methods
We retrospectively analyzed multiple real-world data sources to calculate epidemiological and health outcomes, QALYs lost and direct medical costs due to influenza in the Swiss adult population. Subgroups included residents 18–49, 50–64 and 65+ years of age. The observation period was week 26, 2016, to week 25, 2019.
Results
Across the three seasons, we estimated seasonal averages of 203,090 (se ±26,717) GP visits for ILI 4,944 (se ± 785) influenza-attributable hospitalizations and 1,355 (se ±169) excess deaths attributable to influenza.
We estimated a total loss of 8,429 (2016/2017), 11,179 (2017/2018) and 7,701 (2018/2019) QALYs due to influenza. On average, 88% of the loss in QALYs was attributed to premature deaths due to influenza.
The total direct medical costs amounted to 44.4 (2016/2017), 77.3 (2017/2018) and 64.5 (2018/2019) million Euros. On average, 79.6% of the total costs arose due to hospitalizations.
Conclusions
In Switzerland, the burden of influenza on patients and payers is significant and particularly high in the elderly population. Policy interventions to increase vaccination rates as well as the uptake of more effective vaccines among the elderly are needed to reduce the burden of influenza.