The cost-effectiveness of trivalent and quadrivalent influenza vaccination in communities in South Africa, Vietnam and Australia

Abstract

Background: To inform national healthcare authorities whether quadrivalent influenza vaccines (QIVs) provide better value for money than trivalent influenza vaccines (TIVs), we assessed the cost-effectiveness of TIV and QIV in low-and-middle income communities based in South Africa and Vietnam and contrasted these findings with those from a high-income community in Australia.

Methods: Individual based dynamic simulation models were interfaced with a health economic analysis model to estimate the cost-effectiveness of vaccinating 15% of the population with QIV or TIV in each community over the period 2003-2013. Vaccination was prioritized for HIV-infected individuals, before elderly aged 65+ years and young children. Country or region-specific data on influenza-strain circulation, clinical outcomes and costs were obtained from published sources. The societal perspective was used and outcomes were expressed in International$ (I$) per quality-adjusted life-year (QALY) gained.

Results: When compared with TIV, we found that QIV would provide a greater reduction in influenza-related morbidity in communities in South Africa and Vietnam as compared with Australia. The incremental cost-effectiveness ratio of QIV versus TIV was estimated at I$4183/QALY in South Africa, I$1505/QALY in Vietnam and I$80,966/QALY in Australia.

Conclusions: The cost-effectiveness of QIV varied between communities due to differences in influenza epidemiology, comorbidities, and unit costs. Whether TIV or QIV is the most cost-effective alternative heavily depends on influenza B burden among subpopulations targeted forvaccination in addition to country-specific willingness-to-pay thresholds and budgetary impact.

Keywords: Cost-effectiveness; Dynamic transmission model; Influenza; Quadrivalent; Trivalent; Vaccination.

Fig. 1

Overview of the interfaced individual based simulation model and the health economic model. HIV: Human Immunodeficiency Virus; QALY: Quality-Adjusted Life Year. The numbers refer to the textual methodology overview given at the beginning of the Methods section.

Fig. 2

Relative proportions of influenza A viruses and influenza B viruses stratified by matched and mismatched lineage (See Supplementary methods Table S4 for more details) by influenza season as used in the model. Split of influenza B by lineage in Vietnam was based on surveillance data from Thailand.

Fig. 3

Cost-effectiveness acceptability curves of implementing influenza vaccination with trivalent influenza vaccine and quadrivalent influenza vaccine in the communities Agincourt (South Africa), Thai Nguyen (Vietnam) and Albany (Australia) over the period 2003–2011, assuming a symptomatic attack rate of 5% (A–C) and 10% (D–F). Results are based on a probabilistic sensitivity analysis with 1000 simulations. I$: International dollar, NV: No vaccination, QIV: Quadrivalent influenza vaccine, SAR: Symptomatic attack rate, TIV: Trivalent influenza vaccine, WTP: Willingness-to-pay.

Fig. 4

Univariate sensitivity analysis of the price premium of QIV over TIV when a SAR of 5% (A) and 10% (B) was assumed. 0% price premium means that the QIV price is equal to the TIV price, while 100% price premium means that the QIV price is double of the TIV price. Aus: Australia, ICER: Incremental cost-effectiveness ratio, I$: International$, QALY: Quality-adjusted life year, QIV: Quadrivalent influenza vaccine, SA: South Africa, SAR: Symptomatic attack rate, TIV: Trivalent influenza vaccine, VN: Vietnam.