Understanding the cost-effectiveness of influenza vaccination in children: methodological choices and seasonal variability.

Background: The universal vaccination of children for influenza has recently been recommended in the UK and is being considered in other developed countries.

Objectives: The aim of this study was to explore the potential costs and benefits of childhood influenza vaccination to gain a better understanding of the key drivers of cost-effectiveness.

Methods: As our case study we examined the cost-effectiveness of vaccination in Australian schoolchildren using an age-stratified Susceptible Exposed Infectious Recovered model.

Results: The results of this study highlight the critical role that methodological choices play in determining the cost-effectiveness of influenza vaccination. These choices include decisions about the structure of the model (including/excluding herd immunity) and what costs and benefits to include in the analysis. In scenarios where herd protection was included we estimated that the program was likely to be cost-effective. The study also illustrates the importance of the inherent seasonal variability of influenza, which can produce counter-intuitive results, with low transmission seasons being easier to control by vaccination but resulting in fewer benefits.

Conclusions: Universal childhood influenza vaccination is likely to be cost-effective if a substantial herd protection effect can be achieved by the program. However, it is important that decision makers understand the role of seasonal variability and the impact of alternative methodological choices in economic evaluations of influenza vaccination.