COST EFFECTIVENESS OF INFLUENZA VACCINE OPTIONS IN US ELDERS
Methods: We used a Markov model to estimate the cost-effectiveness of influenza vaccination strategies over a single 10 month influenza season in persons aged ≥65. Vaccination and influenza occurred based on 5-year US monthly averages. The analysis took a societal perspective, with model parameters derived from CDC data, national databases, and medical literature sources. In the base case analysis, we assumed equal vaccine uptake between strategies and no indirect vaccination effects. Vaccine costs were: TIV $10.69, QIV $16.15, and high dose TIV $24.69. One-way and probabilistic sensitivity analyses were performed to test model robustness.
Results: In the base case, total influenza costs were $4.13 higher with TIV compared to no vaccination while gaining 0.0011 QALYs, or $3690 per QALY gained. Compared to TIV, high dose TIV cost $3.73 more and gained 0.0003 QALYS, or $12,300/QALY gained. QIV was eliminated due to extended dominance. One-way sensitivity analyses revealed a robust model: high dose TIV was favored at a $100,000/QALY threshold unless: 1) the increase in relative effectiveness of high-dose TIV compared to TIV is <11.0% (base case 24.2%), favoring QIV; or 2) TIV effectiveness falls below 9.8% (base case 39%), favoring no vaccination. QIV, with its added influenza B component, was not favored when the likelihood of influenza B types were varied in plausible ranges. In a probabilistic sensitivity analysis, varying parameters simultaneously over distributions 5000 times, high dose TIV is favored in 67% of iterations at a $50,000/QALY threshold and in 80% at $100,000/QALY.
Conclusion: High dose TIV for adults ≥65 is very likely to be an economically reasonable influenza vaccination strategy. A revision of CDC influenza vaccination recommendations for elders may be warranted.