Research Article: Economic analysis of adjuvanted trivalent influenza vaccine for older adults in the Korean National Immunization Program
Abstract:
Seasonal influenza causes substantial morbidity and mortality among older adults in South Korea despite high vaccination coverage. The MF59-adjuvanted trivalent influenza vaccine (aTIV) has shown superior immunogenicity in older populations, but its economic value within the Korean National Immunization Program (NIP) has not been evaluated using a dynamic transmission model that captures indirect protection. This study evaluated the budget impact of introducing aTIV into the Korean NIP for adults aged ?65?years.
We developed an age-structured dynamic compartmental model to simulate seasonal influenza transmission in South Korea, allowing estimation of both direct and indirect protection effects. From the healthcare payer perspective and over a single influenza season, we performed a budget impact analysis complemented by a cost–benefit comparison of avoided medical costs against incremental vaccination expenditures. Two aTIV strategies were compared against standard quadrivalent influenza vaccine (QIV) within the NIP framework: Strategy I (aTIV for adults aged ?75?years) and Strategy II (aTIV for all adults aged ?65?years). Deterministic one-way sensitivity analyses examined relative vaccine effectiveness (rVE) of aTIV versus QIV across 5–30% and seasonal attack rate across ±20% of the 8.0% baseline, and a break-even analysis identified the rVE threshold at which incremental costs equal avoided treatment costs. A probabilistic sensitivity analysis was also conducted to quantify joint parameter uncertainty.
At baseline (rVE 25%, attack rate 8.0%), Strategy I required $24.6 million in additional vaccine investment, with 52% offset by treatment savings, yielding a net budget impact of $11.7 million (+0.9% of total influenza-related healthcare expenditure). Strategy II required $54.4 million in additional costs with 57% offset ($31.2 million in savings), resulting in a net impact of $23.2 million (+1.8%). Strategy II prevented 535 deaths and over 15,000 hospitalizations—2.2-fold greater than Strategy I. The incremental cost of aTIV decreased with increasing transmission intensity, approaching cost neutrality during severe epidemic seasons. The break-even rVE at which aTIV becomes cost-saving was 44%, above central meta-analytic estimates (10–25%) but potentially attainable in severe seasons or specific subpopulations.
Introduction of aTIV into the Korean NIP is budget-feasible with substantial health benefits, requiring only a 0.9–1.8% increase in total influenza-related healthcare expenditure. At current rVE estimates (?30%), aTIV does not achieve cost savings, but the additional fiscal burden remains modest. Strategy II offers superior health outcome value and is preferred when budget permits, while Strategy I provides a fiscally conservative entry point. The value proposition of aTIV is most favorable during severe influenza seasons.
Introduction:
Seasonal influenza causes substantial morbidity and mortality among older adults in South Korea despite high vaccination coverage. The MF59-adjuvanted trivalent influenza vaccine (aTIV) has shown superior immunogenicity in older populations, but its economic value within the Korean National Immunization Program (NIP) has not been evaluated using a dynamic transmission model that captures indirect protection. This study evaluated the budget impact of introducing aTIV into the Korean NIP for adults aged ?65?years.
Read more