Effect of incubation period on epidemic spreading in complex networks

We study the effect of incubation period on epidemic spreading in the Barabasi--Albert scale-free network and the Watts--Strogatz small world network by using a Suspectable-Incubated-Infected-Suspectable model. Our analytical investigations show that the epidemic threshold is independent of incubation period in both networks, which is verified by our large-scale simulation results. We also investigate the effect of incubation period on the epidemic dynamics in a supercritical regime. It is found that with the increase of incubation period \it\Omega , a damped oscillation evolution of \rho_T (the ratio of persons in incubated state) appears and the time needed to reach a saturation value increases. Moreover, the steady value of \rho _T increases and approaches to an asymptotic constant with the value of \it\Omega increasing. As a result, the infected ratio \rho _I decreases with the increase of \it\Omega according to a power law.