Economic Impacts of Initiating Vaccination at 3 Months vs. 6 Months in an Influenza Pandemic in the United States

<b>Background/Objectives:</b> An influenza pandemic is likely to occur in the coming decades and will be associated with substantial healthcare and financial burdens. In this study, we evaluated the potential economic costs of different vaccination scenarios for the US population in the context of a moderate or severe influenza pandemic. <b>Methods:</b> Economic analysis was performed for initiation of pandemic vaccination from 3 months vs. 6 months in the US after declaration of a pandemic. We evaluated three vaccine effectiveness levels (high, moderate, low) and two pandemic severity levels (moderate and severe). <b>Results:</b> No vaccination would lead to total direct and indirect costs of $116 bn in a moderate pandemic and $823 bn in a severe pandemic. Initiation of vaccination at 3 months would result in cost savings versus no vaccination (excluding vaccine price) of $30-84 bn and $260-709 bn in a moderate and severe pandemic, respectively, whereas initiation of vaccination at 6 months would result in cost savings of $4-11 bn and $36-97 bn, respectively. Cost savings of $20 bn and $162 bn would occur in a moderate or severe pandemic, respectively, from use of a low effectiveness vaccine from 3 months instead of a high effectiveness vaccine from 6 months. <b>Conclusions:</b> Rapid initiation of vaccination would have a greater impact than increased vaccine effectiveness in reducing the economic impacts of an influenza pandemic.