Abstract
The behavioral response of individuals to an epidemic, and the timing of their behavior change, can have important consequences for epidemic dynamics. While the importance of behavior-change for epidemic dynamics is broadly recognized, the approaches to modeling the coupled dynamics of epidemics and behavior change have been limited. An important mode of behavior change in epidemics is a reduction in potentially infectious contacts. We develop a model for endogenous change of the effective contact rate of Susceptible-Infectious-Susceptible (SIS) epidemic model by positing a dynamic utility function associated with the expected number of contacts people have in the population. This utility function trades off the ideal number of social contacts with the expected cost of becoming infected. Our analysis of this simple, deterministic model reveals the existence of a non-zero endemic equilibrium, oscillatory dynamics under some parametric conditions, and complex dynamic regimes that shift under small parameter perturbations. Time-lag between current epidemic conditions and behavioral response is essential for the more exotic dynamics. These results suggest that reducing this lag may reduce both the final-size of the epidemic and the uncertainty associated with epidemic projections.
Competing Interest Statement
The authors have declared no competing interest.