Cost-effectiveness analysis of quadrivalent influenza vaccination in at-risk adults and the elderly: an updated analysis in the UK

Objective: To update an earlier evaluation estimating the cost-effectiveness of quadrivalent influenza vaccination (QIV) compared with trivalent influenza vaccination (TIV) in the adult population currently recommended for influenza vaccination in the UK (all people aged >= 65 years and people aged 18-64 years with clinical risk conditions). Methods: This analysis takes into account updated vaccine prices, reference costs, influenza strain circulation, and burden of illness data. A lifetime, multi-cohort, static Markov model was constructed with seven age groups. The model was run in 1-year cycles for a lifetime, i.e., until the youngest patients at entry reached the age of 100 years. The base-case analysis was from the perspective of the UK National Health Service, with a secondary analysis from the societal perspective. Costs and benefits were discounted at 3.5%. Herd effects were not included. Inputs were derived from systematic reviews, peer-reviewed articles, and government publications and databases. One-way and probabilistic sensitivity analyses were performed. Results: In the base-case, QIV would be expected to avoid 1,413,392 influenza cases, 41,780 hospitalizations, and 19,906 deaths over the lifetime horizon, compared with TIV. The estimated incremental cost-effectiveness ratio (ICER) was 14,645 pound per quality-adjusted life-year (QALY) gained. From the societal perspective, the estimated ICER was 13,497 pound/QALY. A strategy of vaccinating only people aged >= 65 years had an estimated ICER of 11,998 pound/QALY. Sensitivity analysis indicated that only two parameters, seasonal variation in influenza B matching and influenza A circulation, had a substantial effect on the ICER. QIV would be likely to be cost-effective compared with TIV in 68% of simulations with a willingness-to-pay threshold of <20,000 pound/QALY and 87% with a willingness-to-pay threshold of <30,000 pound/QALY. Conclusions: In this updated analysis, QIV was estimated to be cost-effective compared with TIV in the UK.