Dynamic properties of the SIR model.

(a) Evolution of the expected number of recovered pupils (solid green line) and the standard deviations (dashed red lines), given that at least one pupil is always infected. (b) The Fano factor (variance/mean) associated with the results in (a) as a function of time. (c) Dynamic evolution of the probability of extinction , . (d) The (approximately stationary) probability mass function at days.