Modeling the waning and boosting of immunity (Prof. Lauren Childs)

Title: Modeling the waning and boosting of immunity

Speaker: Dr. Lauren Childs

Assistant Professor and the Cliff and Agnes Lilly Faculty Fellow
Virgina Tech

Abstract: Infectious disease often leads to significant loss of life and burden on society. Understanding disease dynamics is essential to the development and implementation of earlier and more effective interventions. Traditionally, perfect, long-lasting protection against disease is assumed to be acquired, but this need not always be the case. Immunity following natural infection (or immunization) may wane, increasing susceptibility with time since exposure. In this talk, we begin by examining a classic model of waning and boosting immunity with a focus on the bifurcation structure and how it changes as reinfection is considered. Then, we discuss an extension of this framework with an age- and immune status-dependent model of disease transmission. In this model, susceptibility, infectiousness, and symptom severity all vary with immune status, while age affects contacts and vaccination.  We examine applications of this model to two diseases: pertussis, commonly known as whooping cough, and COVID-19. For pertussis, we examine age-specific incidence and prevalence and find vaccination leads to a resurgence of immunity-modified pertussis in older children, as observed with effective vaccination programs. For COVID-19, we examine the role of waning and boosting immunity to estimate seroprevalence in Canada and to evaluate vaccination strategies. We find a large fraction of the Canadian population with some immunity following infection or vaccination, but that the quality and longevity of this immunity decreases with time. Using contact and demographic data from specific locations coupled with disease-specific parameterization, our model has the potential to assist in the development and optimization of vaccination schedules. This is important to mitigate resurgence of immunity-modified disease due to natural boosting.

Dr. Lauren Childs is an Assistant Professor in the Department of Mathematics and the Cliff and Agnes Lilly Faculty Fellow in the College of Science at Virginia Tech. Her research focuses on developing and analyzing mathematical and computational models for a better understanding of the dynamics of infectious diseases, in particular vector-borne diseases such as malaria. Her research emphasizes the interactions within a host organism, such as between an invading pathogen and the immune response, and the impacts of such interactions on transmission between individuals in the population.