Methods and Findings
We developed an age-structured model to evaluate the cost-effectiveness of eight vaccination
policies parameterized using country-level data from Thailand. For policies using LAIV,
we considered five different age groups of children to vaccinate. We adopted a Bayesian
evidence-synthesis framework, expressing uncertainty in parameters through probability
distributions derived by fitting the model to prospectively collected laboratory-confirmed influenza
data from 2005-2009, by meta-analysis of clinical trial data, and by using prior probability
distributions derived from literature review and elicitation of expert opinion. We
performed sensitivity analyses using alternative assumptions about prior immunity, contact
patterns between age groups, the proportion of infections that are symptomatic, cost per
unit vaccine, and vaccine effectiveness. Vaccination of children with LAIV was found to be
highly cost-effective, with incremental cost-effectiveness ratios between about 2,000 and
5,000 international dollars per disability-adjusted life year averted, and was consistently preferred
to TIV-based policies. These findings were robust to extensive sensitivity analyses.
The optimal age group to vaccinate with LAIV, however, was sensitive both to the
willingness to pay for health benefits and to assumptions about contact patterns between
age groups.