BACKGROUND: As of 2019, quadrivalent influenza vaccine (QIV), rather than trivalent (TIV), has been implemented in the national immunization program in The Netherlands. Specifically invited are individuals of 60+ years of age and those with chronic diseases. QIV contains both of the influenza-A and influenza-B strains, while TIV only contains one influenza-B strain, which has led to mismatches in previous influenza seasons between the circulating influenza B strain and the strain selected for the vaccine.

OBJECTIVES: To estimate the break-even price of the switch from TIV to QIV in the Dutch National Influenza Prevention Program at a threshold of €20,000 per quality-adjusted life year (QALY).

METHODS: An age-structured compartmental dynamic model was adopted to assess health and cost outcomes of vaccinating all individuals in the Netherlands at higher risk for influenza with QIV. Influenza incidence rates were derived from Flunet, a global influenza surveillance database. Other parameters – such as transition probabilities, QALYs and costs - were extracted from the literature and were applied according to the Dutch guidelines. The incremental cost-effectiveness ratio (ICER) was analyzed for the base-case break-even price and sensitivity analyses were performed to test the robustness of our approach.

RESULTS: Vaccination with QIV is expected to prevent 9,500 additional symptomatic influenza cases per year, including 2130 outpatient visits, 84 hospitalizations and 38 deaths, compared to vaccination with TIV. This translates into 385 QALYs and 398 life years gained. A total of €431,527 direct and €2,388,810 indirect costs were saved. Assuming a conservative willingness to pay threshold of €20,000 per QALY, the QIV break-even price was estimated at €3.61 from the societal perspective.

CONCLUSIONS: The use of QIV over TIV was estimated cost-effective at a maximum incremental price of QIV over TIV of €3.61. Results were robust in sensitivity analyses.