ECONOMIC EVALUATION OF AN INFLUENZA IMMUNIZATION PROGRAM

Abstract

<p><strong>Objective</strong>: To estimate the cost-effectiveness of an influenza immunization strategy directed at healthy children 36 months to 15 years on the herd immunity of entire communities, versus not implementing this strategy.</p> <p><strong>Design</strong>: An economic evaluation, cost-effectiveness analysis (CEA). Costs and effects were estimated jointly with a two-stage bootstrap with shrinkage correction. Uncertainties around input parameters were tested with one-way and multi-way sensitivity analysis.</p> <p><strong>Data Sources</strong>: Effect and resource consumption data were from the Hutterite Influenza Prevention Study. Unit costs were collected from multiple sources including, government reports and schedules, local suppliers, peer-reviewed articles and systematic reviews, Internet searches and study data on file.</p> <p><strong>Outcomes</strong>: Mean costs and effects, incremental cost-effectiveness ratio (ICER), net monetary benefit (NMB) statistic and cost effectiveness acceptability curves (CEAC).</p> <p><strong>Results</strong>: The average cost per patient in the treatment arm was $69.08 and $32.66 in the control arm. The average number of influenza-free cases was of 0.96 in the treatment arm and 0.73 in the control arm. ICER was $164.19 per case of influenza averted, 95% confidence interval $28.38, $2,767.75. CEAC showed that at a willingness to pay of $177, the probability of the treatment strategy being cost effective compared to the control was 0.50. Results from sensitivity analyses were slightly different compared to base case results, supporting the robustness of base case estimates.</p> <p><strong>Conclusion</strong>: This strategy is likely to be cost effective relative to the comparator as the ICER estimate is low and because the estimate is conservative given that the study population was very healthy and the influenza season was mild. A more virulent season and a less healthy population would have produced a lower ICER or seen the treatment arm dominate the control.</p>