It is not ethical, and often not possible, to assess the effect of possible interventions by conducting experiments with real communities. As a result, mathematical models that describe the transmission of infectious diseases are a valuable tool for planning the management and control of infectious diseases.
The use of mathematical models to evaluate an intervention proceeds by first constructing a mathematical model that describes the transmission of the infection. Such a model is necessarily a simplification of the real world, but is a useful basis for the evaluation as long as it contains the essential characteristics of transmission of the infection in the community. One requirement is that the description provided by the model must agree with all relevant empirical data that are available. The next step is to modify the model in a way that reflects the proposed intervention. Then the outcomes predicted by the original model and the modified model are compared, to assess what effect, if any, the proposed intervention has on the outcome of interest.
Applications of transmission models to assess strategies for infectious disease control include the assessment of vaccination strategies [Anderson and May (1991)], predictions of epidemics [see for example Ramsay et al. (1994), Roberts and Tobias (2000)], strategies for the control of foot and mouth disease [see Green and Medley (2002) for a review], assessing the effect of interventions used in the control of SARS and recent modeling assessing the potential for controlling an emerged pandemic of influenza [see for example Longini et al. (2004, 2005) and Ferguson et al. (2005)].