Formulating human risk response in epidemic models: exogenous vs endogenous approaches

TL;DR

This paper reviews how human risk response is modeled in epidemic models, comparing fixed-parameter (exogenous) and internally driven (endogenous) approaches to better understand behavioral impacts on disease spread.

Contribution

It categorizes and analyzes 37 papers on epidemic modeling, highlighting the differences between exogenous and endogenous risk response frameworks and their implications.

Findings

Endogenous models incorporate internal mechanisms for behavior change.

Exogenous models use fixed parameters to represent behavior shifts.

The review offers guidance for selecting appropriate modeling frameworks.

Abstract

The recent pandemic emphasized the need to consider the role of human behavior in shaping epidemic dynamics. In particular, it is necessary to extend beyond the classical epidemiological structures to fully capture the interplay between the spread of disease and how people respond. Here, we focus on the challenge of incorporating change in human behavior in the form of "risk response" into compartmental epidemiological models, where humans adapt their actions in response to their perceived risk of becoming infected. The review examines 37 papers containing over 40 compartmental models, categorizing them into two fundamentally distinct classes: exogenous and endogenous approaches to modeling risk response. While in exogenous approaches, human behavior is often included using different fixed parameter values for certain time periods, endogenous approaches seek for a mechanism internal to the model to explain changes in human behavior as a function of the state of disease. We further discuss two different formulations within endogenous models as implicit versus explicit representation of information diffusion. This analysis provides insights for modelers in selecting an appropriate framework for epidemic modeling.