The strength and duration of acquired immunity are important yet understudied determinants of the dynamics and evolution of infectious diseases. Inspired by observations of an apparent resurgence of whooping cough (causative agent the bacterium Bordetella pertussis), we examined models in which infection or vaccination results in temporary immunity to reinfection and in which re-exposure results in boosting of immunity. We explored the predictions of these models with respect to dynamics and age-stratified incidence.
Results/Conclusions
The dynamical repertoire of such models is surprisingly rich and includes multiple coexisting attractors. These attractors correspond to very distinct dynamical regimes and may explain some of the observed patterns in whooping cough incidence following the implementation of vaccination programs.
