Tuesday, October 21, 2008: 12:30 PM
Grand Ballroom B/C (Hyatt Regency Penns Landing)
Nayer Khazeni, MD, MS1, David W. Hutton, MS1, Alan Garber, MD, PhD2 and Douglas K. Owens, MD, MS3, (1)Stanford University, Stanford, CA, (2)Veterans Affairs Palo Alto Health Care System and Stanford University, Stanford, CA, (3)VA Palo Alto Health Care System & Stanford University, Palo Alto, CA
Purpose: Although expenditures for pandemic influenza preparedness have reached $6 billion in the United States, the cost effectiveness of alternative public health strategies for the control of pandemic influenza are not known. We evaluated the cost-effectiveness of two strategies: a strategy providing 40% of the population with an adjuvanted prime-boost vaccination (in which a pre-pandemic vaccine is followed by a booster once the pandemic begins), and a strategy providing broadly-distributed antiviral prophylaxis to 40% of the population.
Methods: We developed a dynamic transmission model of pandemic Influenza A H5N1 in a large U.S. city. We used decision analysis to calculate expected values of societal costs and benefits of the two strategies and the status quo, which involves limited prophylaxis and unadjuvanted vaccination for less than 10% of the population. We measured outcomes in costs, infections and deaths averted, quality-adjusted life-years (QALYs) gained, and incremental cost-effectiveness. We estimated transmissibility, morbidity and mortality of pandemic Influenza A H5N1 from the literature. We estimated effectiveness of interventions from the literature and expert opinions of influenza researchers. We estimated costs from the literature and expert opinions of public health and hospital officials. All parameter assumptions were tested in sensitivity analyses.
Results: Adjuvanted prime-boost vaccination was the most effective and most cost-effective strategy, averting 33% of infections and 33% of deaths compared to the status quo at a cost of 6,864 USD/QALY gained. Broadly distributed antiviral prophylaxis was effective only for limited duration of use; it averted 4% of infections and 4% of deaths as compared with the status quo, and its cost-effectiveness was dominated by the vaccination strategy. The major drivers of expected cost-effectiveness of the vaccination strategy are the probability of a pandemic occurring and the effectiveness of the vaccine. However, the strategy is still cost-effective even with a low probability of pandemic and relatively ineffective vaccine: with a 1% annual probability of pandemic and a vaccine with 20% effectiveness in reducing infection, the expected cost-effectiveness is 43,175 USD/QALY.
Conclusions: Adjuvanted prime-boost vaccination is an effective and cost-effective preventive strategy for an Influenza A H5N1 pandemic. Broadly distributed antiviral prophylaxis can be beneficial in delaying the pandemic, but is unlikely to be effective in preventing a pandemic.
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