Modelling the impact of vaccination strategies

Many questions in planning for vaccination strategies are not easily answered. In order to assess the expected impact of vaccination on incidence of infection and disease we have to account explicitly for the transmission process of infectious agents, and the interference of vaccination with transmission of infection or disease. This requires, in one way or another, a mathematical description and analysis of the transmission of infection. We shall briefly discuss the basic structure of epidemic models that are used for evaluating vaccination strategies. We shall confront the findings with observations, and we shall review some practical cases where modelling vaccination strategies has provided crucial insights into how vaccination affects patterns of disease incidence.