ABSTRACT
In this chapter, we provide an introduction to the analysis of seroprofiles of immunity, focusing on the example of directly transmitted, completely immunizing infections, such as measles and rubella. The serological titer associated with protection from infection (or immunity) is often known for such pathogens. This opens the way to investigating drivers of population-scale pathogen dynamics by leveraging individual covariates such as age, with important policy applications. To set the role of seroprofiles of immunity in the public health context, we first introduce alternate epidemiological data sources and methods used to measure population immunity. We then define expectations and determinants of the age profile of immunity of directly transmitted infections, and introduce basic mathematical and statistical methods to characterize aspects of the landscape of immunity from both continuous and binary serological response variables. We then work through a case study for the use of rubella IgG serology in public health, providing a detailed overview of methods required to estimate epidemiological parameters and to make vaccine policy recommendations. We conclude with a discussion on the challenges of using serological data and outline directions for further statistical and methodological innovation. Through this chapter, we aim to provide an introduction to basic methods for analyzing serological data and their potential public health application, and to point to key references that expand upon these methods.
