Solution of an infection model near threshold
arXiv:q-bio/0701024 · doi:10.1103/PhysRevE.76.010901
Abstract
We study the Susceptible-Infected-Recovered model of epidemics in the vicinity of the threshold infectivity. We derive the distribution of total outbreak size in the limit of large population size . This is accomplished by mapping the problem to the first passage time of a random walker subject to a drift that increases linearly with time. We recover the scaling results of Ben-Naim and Krapivsky that the effective maximal size of the outbreak scales as , with the average scaling as , with an explicit form for the scaling function.