RESEARCH Cost-effectiveness of Phar maceutical-based Pandemic Inﬂuenza Mitigation Strategies1 Anthony T. Newall, James G. Wood, Noemie Oudin, and C. Raina MacIntyre We used a hybrid transmission and economic model lay but such vaccine is likely to provide lower efﬁcacy than to evaluate the relative merits of stockpiling antiviral drugs a matched vaccine. There is also a substantial risk that the and vaccine for pandemic inﬂuenza mitigation. In the ab- pandemic strain will be of a different subtype than that cho- sence of any intervention, our base-case assumptions gen- sen for the stockpiled vaccine. The emergence of pandemic erated a population clinical attack rate of 31.1%. For at least (H1N1) 2009 illustrates this point. tspiooanmndesetrmpaaitcreagi mnieﬂesuteewrnezvraaeluueenffstei,lcptthiovepeuaalratritvicoaonlnotpafrienapinmagnadatcenhmeoidcutvbvaareccacckiinnaoe-f. beenMuastehdemtoatiacsaslesmsothdeelsfeoasfibdiilsiteyasoef tpraannsdme missicionmihtiagvae- Because of the uncertain nature of many parameters, we tion strategies (5–10). However, of the limited numbers of used a probabilistic approach to determine the most cost- published economic evaluations on pandemic stockpiling effective strategies. At a willingness to pay of >A$24,000 (11–14), to our knowledge only 1 recent study has attempt- per life-year saved, more than half the simulations showed ed to directly model herd protection (14). We explored the that a prepandemic vaccination program combined with an- cost-effectiveness of stockpiling prepandemic vaccine and tiviral treatment was cost-effective in Australia. antiviral drugs for pandemic inﬂuenza mitigation. Iin the last century (1918, 1957, and 1968); the ﬁrst inﬂu- nﬂuenza pandemics of varying severity occurred 3 times enza pandemic of the 21st century occurred in 2009. Be- fore this latest pandemic, awareness had been heightened by the emergence of the highly pathogenic (H5N1) strain (1). In response, many countries have developed detailed plans aimed at the mitigation of a future pandemic. A key aspect of many pandemic plans is the stockpiling of anti- viral drugs (neuraminidase inhibitors) for treatment or pro- phylaxis (2,3). The stockpiling of prepandemic vaccine is also an area of active consideration (4). Although a matched vaccine (developed speciﬁcally for the emergent strain) is likely to offer the best protection, the delay in producing such a vac- cine is a major obstacle. The stockpiling of prepandemic vaccine based on currently available strains avoids this de- Author afﬁliations: University of New South Wales, Sydney, New South Wales, Australia (A.T. Newall, J.G. Wood, C.R. MacIntyre); and National Institute for Applied Sciences, Lyon, France (N. Oudin) DOI: 10.3201/eid1602.090571 Methods Overview An age-stratiﬁed transmission model (susceptible, ex- posed, infected, removed) was used to calculate clinical at- tack rates (CAR) and antiviral drug consumption, which became inputs in a decision analytic economic model as represented in Figure 1 (MATLAB version 2008a [www. mathworks.com]). The primary outcome from the economic model was the incremental cost per life-year saved (LYS). Economic results are reported per person in the population to facilitate understanding for an international audience. We addressed the uncertainty in many of the model pa- rameters by performing extensive sensitivity analyses, in- cluding probabilistic sensitivity analysis using 5,000 Latin hypercube samples drawn from parameter distributions. A detailed description of the transmission model and a full list of model parameters and distributions can be found 1This material was compiled before the declaration of pandemic (H1N1) 2009 and concerns stockpiling for a future inﬂuenza pandemic. 224 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 16, No. 2, February 2010