Economic evaluation of an influenza immunization strategy of healthy children.

OBJECTIVES: Vaccinating healthy children is proposed as a strategy to produce a herd effect and protect vulnerable groups. The Hutterite Influenza Prevention Study investigated this strategy, comparing communities with or without childhood influenza immunization programs. There are costs associated with vaccination therefore there may be a trade-off between these costs and the benefits of avoiding influenza cases. This evaluation estimates the cost-effectiveness of immunizing only healthy children in preventing cases of influenza within entire communities. METHODS: Effect data and resource utilization were collected during the trial. Cost data were collected from payer, literature and Internet sources. A two-stage bootstrap (TSB) with shrinkage correction was used to estimate average costs and effects. The incremental cost effectiveness ratio (ICER) and sample uncertainty around this estimate were calculated from the TSB results. RESULTS: Mean costs per patient for the treatment and control arms were $69.07 and $32.66 (difference $36.41). Mean number of influenza cases for the treatment and control arms were 0.04 and 0.27 (difference 0.23). ICER was $164.12 ($28.38, $2767.75) per case of influenza averted. CONCLUSIONS: Immunizing healthy children for influenza is more costly, yet more effective than no immunization in preventing cases in the sample. At a cost of $164.12 to prevent a case of influenza, immunizing healthy children to protect all community members may be considered costeffective. Estimated results are conservative as the influenza season was mild and the sample population was healthy. In a more severe season with a less healthy population the ICER is expected to decrease.