The Timing and Nature of Behavioural Responses Affect the Course of an Epidemic

Tyson RC, Hamilton SD, Lo AS, Baumgaertner BO, and Krone SM

Abstract

During an epidemic, the interplay of disease and opinion dynamics can lead to outcomes that are different from those predicted based on disease dynamics alone. Opinions and the behaviours they elicit are complex, so modeling them requires a measure of abstraction and simplifcation. Here, we develop a differential equation model that couples SIR-type disease dynamics with opinion dynamics. We assume a spectrum of opinions that change based on current levels of infection as well as interactions that to some extent amplify the opinions of like-minded individuals. Susceptibility to infection is based on the level of prophylaxis (disease avoidance) that an opinion engenders. In this setting, we observe how the severity of an epidemic is in uenced by the distribution of opinions at disease introduction, the relative rates of opinion and disease dynamics, and the amount of opinion amplifcation. Some insight is gained by considering how the effective reproduction number is in uenced by the combination of opinion and disease dynamics.