PIN60 Cost-Effectiveness of Quadrivalent Influenza Vaccine High Dose Versus Adjuvanted Standard Dose Trivalent Influenza Vaccine in England

Abstract

Influenza is recognised as an important cause of morbidity and mortality in human populations, resulting in an average of over 21,000 influenza-associated deaths each year in England alone, with 85% of influenza-associated deaths in those over the age of 65. Quadrivalent Influenza Vaccine High-Dose (QIV-HD) has been specifically developed for the over 65 population, containing 4-times more antigen than current standard dose (SD) vaccines. The objective of this study is to estimate the cost-effectiveness of QIV-HD compared to adjuvant Trivalent Influenza Vaccine (aTIV) using clinically relevant endpoints. A static decision tree model was used to compare influenza cases, GP consultations, hospitalisations, and deaths resulting from influenza complications. Due to a sparsity of trial-based evidence and heterogeneous findings from observational studies for aTIV, three different relative vaccine efficacy scenarios were investigated for QIV-HD versus aTIV. In addition, cost-effectiveness was assessed for QIV-HD versus aTIV for a base case analysis in which hospitalisations were defined as due to influenza/pneumonia. Discounted QALY losses were included for hospitalisations and in-hospital deaths. Analyses were conducted from a UK healthcare system perspective over a one-year time horizon. Base case results, with hospitalisation defined as influenza/pneumonia events, indicate that QIV-HD would be considered a cost-neutral vaccination strategy (ICER: £824/QALY), considerably below the £20,000 willingness to pay threshold, delivering superior health outcomes in the over 65 population compared with the current approach using aTIV. When broader definitions of hospitalisations were considered, QIV-HD was shown to be the dominant vaccination strategy compared to aTIV across most scenarios assuming various vaccine efficacy inputs for aTIV for both lab-confirmed influenza cases and hospitalisations. QIV-HD could be a highly cost-effective, and in some cases dominant, alternative to aTIV in England and could reduce the annual public health burden of influenza-related complications.