A Small Community Model for the Transmission of Infectious Diseases: Comparison of School Closure as an Intervention in Individual-Based Models of an Influenza Pandemic George J. Milne1*, Joel K. Kelso1, Heath A. Kelly1,2,3, Simon T. Huband1, Jodie McVernon3 1 School of Computer Science and Software Engineering, The University of Western Australia, Crawley, Western Australia, Australia, 2 Epidemiology Unit, Victorian Infectious Diseases Reference Laboratory, Carlton, Victoria, Australia, 3 School of Population Health, University of Melbourne, Carlton, Victoria, Australia Abstract Background: In the absence of other evidence, modelling has been used extensively to help policy makers plan for a potential future influenza pandemic. Method: We have constructed an individual based model of a small community in the developed world with detail down to exact household structure obtained from census collection datasets and precise simulation of household demographics, movement within the community and individual contact patterns. We modelled the spread of pandemic influenza in this community and the effect on daily and final attack rates of four social distancing measures: school closure, increased case isolation, workplace non-attendance and community contact reduction. We compared the modelled results of final attack rates in the absence of any interventions and the effect of school closure as a single intervention with other published individual based models of pandemic influenza in the developed world. Results: We showed that published individual based models estimate similar final attack rates over a range of values for R0 in a pandemic where no interventions have been implemented; that multiple social distancing measures applied early and continuously can be very effective in interrupting transmission of the pandemic virus for R0 values up to 2.5; and that different conclusions reached on the simulated benefit of school closure in published models appear to result from differences in assumptions about the timing and duration of school closure and flow-on effects on other social contacts resulting from school closure. Conclusion: Models of the spread and control of pandemic influenza have the potential to assist policy makers with decisions about which control strategies to adopt. However, attention needs to be given by policy makers to the assumptions underpinning both the models and the control strategies examined. Citation: Milne GJ, Kelso JK, Kelly HA, Huband ST, McVernon J (2008) A Small Community Model for the Transmission of Infectious Diseases: Comparison of School Closure as an Intervention in Individual-Based Models of an Influenza Pandemic. PLoS ONE 3(12): e4005. doi:10.1371/journal.pone.0004005 Editor: Joel Mark Montgomery, U.S. Naval Medical Research Center Detachment/Centers for Disease Control, United States of America Received June 16, 2008; Accepted November 20, 2008; Published December 23, 2008 Copyright: 2008 Milne et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Funding from the National Health and Medical Research Council, Australia (grant number 404189), and from the Commonwealth Department of Health and Ageing, Australia, is acknowledged. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: joel@csse.uwa.edu.au Introduction With continuing concern about the possibility of another influenza pandemic, many models have been developed to predict the course of the pandemic and the effect of potential intervention strategies. Approaches to modelling the spread of infectious respiratory diseases have included deterministic [1,2], stochastic [3–5] and individual-based models [6–12]. These models have ranged in focus from the whole world [1,3,4], through large [8,10] and small [7,9] countries, to synthetic small communities [11]. However, while there are many individual-based models, no model constructed to date has focused on a precise replication of a small community, with detail down to individual schools, employers, and the exact make-up of households as extracted from census datasets. We have developed a detailed spatio-temporal model of the Albany town and surrounding district. Albany, a relatively isolated community of approximately 30,000 people in the south of Western Australia, is a regional centre with one major hospital, one technical college, 22 schools and approximately 1200 employers. We believe that this modelled population provides us with a large enough experimental test-bed to capture the daily mobility of individuals as found in a developed nation. Using this model we examined the impact that social distancing measures might have in mitigating an influenza pandemic, given that social distancing measures can be implemented early in a pandemic by developed and developing countries alike. We aimed to demonstrate the development of the model and its application to a human pandemic, with a pandemic virus PLoS ONE | www.plosone.org 1 December 2008 | Volume 3 | Issue 12 | e4005