Seasonal and pandemic influenza vaccination of pregnant women: An economic simulation model

Objectives/Research Questions: Evaluate the cost-effectiveness of seasonal and pandemic vaccination strategies (single and two-dose) for immunizing pregnant women against laboratory-confirmed influenza.

Methods: Comparisons were made between not vaccinating and vaccinating all pregnant women in the U.S. for influenza using a decision analytic computer simulation model. Monte Carlo probabilistic sensitivity analyses were performed to determine the robustness of results by varying influenza prevalence, maternal influenza-attributable mortality, vaccine efficacy for both mother and neonate, and number of doses required. Incremental cost-effectiveness ratios (ICERs) were the main outcomes measure.

Results: Single and two-dose influenza vaccination strategies are cost-effective (ICER<$0,000) when influenza prevalence ≥7.5% and influenza-attributable mortality is ≥1.05%. Incremental value of vaccination increases as the prevalence and/or the severity of the outbreak increases. A single-dose strategy is dominant, (i.e. less costly and prevents more adverse clinical outcomes), when influenza prevalence is ≥25% and maternal probability of influenza-attributable mortality ≥2.1% (twice the baseline risk).

Conclusions: Immunization of pregnant women is a highly cost-effective intervention at both seasonal and pandemic scenarios. This suggests the optimization of maternal vaccination efforts, which often have low vaccine coverage. Even in seasonal scenarios, maternal immunization is cost-effective.

Implications for Public Health: Historically, seasonal and pandemic influenza have disproportionately affected pregnant women and neonates. Determining the cost-effectiveness of maternal immunization is important because public health dollars and doses of vaccines can both be limited.