Complex dynamics induced by delayed adaptive behavior during epidemics

Ronan F. Arthur; James H. Jones; Matthew H. Bonds; Marcus W. Feldman

Observed epidemic curves of many transient disease outbreaks typically inflect and go extinct, as opposed to this model that oscillates perpetually or converges to an endemic disease equilibrium. Our model is meant to demonstrate what effect personal incentives can have on infectious disease dynamics. Including institutional and public efforts that are incentivized to eradicate, rather than to optimize personal utility trade-offs, would alter the dynamics to look more like real-world epidemic curves. This may have a useful implication for policy. For example, beyond infectious diseases that remain endemic to society, outbreaks may also flare up once or multiple times, such as the double-peaked outbreaks of SARS in 3 countries in 2003 [44] . There may be many causes for such double-peaked outbreaks, one of which may be a lapse in behavior change after the epidemic begins to die down due to decreasing incentives, as represented in our simple theoretical model [17] . This is consistent with findings that voluntary vaccination programs suffer from decreasing incentives to participate as prevalence decreases [45, 46] .