Expanding enhanced influenza vaccines programs for adults aged ≥65 in the Nordic region predicted to improve public health and health system resilience

BACKGROUND: Influenza continues to pose a significant recurring challenge for public health and healthcare systems. Influenza infection can cause short-term complications leading to hospitalisations, or death, and may require post-discharge care at home or in nursing facilities. Additionally, the economic burden of influenza is substantial and impacts healthcare resources and budgets. Enhanced influenza vaccines (EIV) have been shown to provide better protection against influenza infection and downstream clinical outcomes. However, access to EIVs remains limited for older adults in the Nordic region. This study predicted clinical events and associated costs that could be saved by investing in enhanced influenza vaccine for all adults aged ≥65. METHODS: A seasonal influenza model was developed as a decision tree, estimating symptomatic infections and following complications and modifying the risk of symptomatic infection with the vaccine effectiveness. National vaccination policies were compared with an EIV program for adults aged ≥65 years. Vaccine effectiveness and clinical probabilities were informed by published studies and costs were derived for each country. RESULTS: For Sweden, Finland, Norway, and Denmark expanding EIV coverage programmes to cover all ≥65-year-olds was predicted to prevent 13,929; 6411; 5951; and 2438 symptomatic influenza cases, respectively. From these averted symptomatic infections, an estimated 1615; 804; 762; 407 life-years were subsequently saved. The estimated reductions in hospitalisation and hospital days were: 786 and 6511; 362 and 2997; 336 and 2782; and 138 and 1140, respectively. The estimated additional budget impact due to vaccine acquisition costs was estimated at €7.7 million in Sweden, €2.5 million in Finland, €4.4 million in Norway, and €2.4 million in Denmark for extending EIV coverage to adults aged ≥65. CONCLUSIONS: Estimated increases in overall healthcare spending associated with expanding EIV programmes could be a low-cost investment in the light of overall healthcare expenditure, considering the substantial gains in public health and healthcare system resilience.