Cost-effectiveness of quadrivalent influenza vaccine in Hong Kong - A decision analysis.

Trivalent influenza vaccine (TIV) selects one of the 2 co-circulating influenza B lineages whereas quadrivalent influenza vaccine (QIV) includes both lineages. We examined potential cost-effectiveness of QIV versus TIV from perspectives of healthcare provider and society of Hong Kong. A decision tree was designed to simulate the outcomes of QIV vs. TIV in 6 age groups: 0-4 years, 5-9 years, 10-14 years, 15-64 years, 65-79 y and ≥80 years. Direct cost alone, direct and indirect costs, and quality-adjusted life-years (QALYs) loss due to TIV-unmatched influenza B infection were simulated for each study arm. Outcome measure was incremental cost per QALY (ICER). In base-case analysis, QIV was more effective than TIV in all-age population with additional direct cost per QALY (ICER-direct cost) and additional total cost per QALY (ICER-total cost) of USD 22,603 and USD 12,558, respectively. Age-stratified analysis showed that QIV was cost-effective in age groups 6 months to 9 y and ≥80 years from provider's perspective, and it was cost-effective in all age group except 15-64 y from societal perspective. Percentage of TIV-unmatched influenza B in circulation and additional vaccine cost of QIV were key influential factors. From perspectives of healthcare provider and society, QIV was the preferred option in 52.77% and 66.94% of 10,000 Monte Carlo simulations, respectively. QIV appears to be cost-effective in Hong Kong population, except for age group 15-64 years, from societal perspective. From healthcare provider's perspective, QIV seems to be cost-effective in very young (6 months-9 years) and older (≥80 years) age groups.