In this paper, we develop a mathematical model to describe the dynamics of reinfection under the assumption that immune protection may wane over time. As a disease control strategy a schedule of primary and secondary (booster) vaccination is studied, with vaccine induced immunity declining over time. A distinction is made between infection in immunological naive individuals (primary infection) and infection in individuals whose immune system has been primed by vaccination or infection (reinfection). Using the model we analyze the association between prevalence of infection and immunity, induced either by infection or by vaccine. The model shows that eradication depends on vaccination coverage as well as on vaccine efficacy. (c) 2006 Elsevier Inc. All rights reserved.189217231736