Cost-effectiveness of influenza vaccination during pregnancy.

Objective: To assess the cost-effectiveness of influenza vaccination for all pregnant patients in the United States.

Methods: We designed a cost-effectiveness model to compare outcomes and costs in pregnant patients who received the inactivated, trivalent influenza vaccine to those who did not. We used a theoretical cohort of 4 million patients, the number of individuals giving birth in the United States per year. We assumed that H1N1 and A or B type influenza were of equal incidence based on seasonal variation from the past ten years. Our outcomes include acquiring H1N1, acquiring A or B type influenza, maternal death, stillbirth, infant death, preterm birth, and cerebral palsy in addition to cost and quality-adjusted life years (QALYs). Probabilities were derived from the literature and QALYs generated at a discount rate of 3%. Sensitivity analyses were performed to assess the robustness of our model.

Results: In our theoretical cohort of 4 million pregnant patients, the influenza vaccination strategy was associated with 1632 fewer stillbirths (24,332 in the vaccine strategy vs. 25,964 in the no vaccine strategy), 120 fewer maternal deaths (284 vs. 404), 340 fewer infant deaths (5608 vs. 5948), 32,856 fewer preterm births (403,896 vs. 436,752), and 641 fewer cases of moderate cerebral palsy (12,388 vs. 13,029). Additionally, the vaccination strategy corresponded to savings of $3.7 billion ($63.3 billion vs. $67.0 billion) and increased QALYs of 81,696 (226,852,076 vs 226,770,380). Therefore, it was considered a dominant strategy. Univariate sensitivity analysis demonstrated that the vaccine is cost saving until vaccine cost passes $900, far above the current cost of $12.16. In addition, we used sensitivity analysis to vary seasonal proportions of H1N1 to A or B type influenza. The vaccine was cost saving and increased QALYs for any proportion of H1N1 to A or B type influenza including when H1N1 was absent.

Conclusion: We demonstrate that in a cohort of 4 million patients, the influenza vaccine may save $3.7 billion per year, improve maternal and infant outcomes, and reduce morbidity and mortality. Our study provides further evidence that providers should strongly recommend that pregnant patients receive their annual influenza vaccine.