Here m indexes all the patients who could potentially have infected patient l. The net single admission reproduction number for patient episode l (i.e. the expected number of secondary cases resulting from this episode) is then given by R l~X m p ml and corresponding reproduction numbers for a given time period are obtained by averaging over these patient reproduction numbers for all patient episodes starting in the given period. Associated confidence intervals are derived by simulation, by repeatedly drawing the source of infection for each of the P w M w new infections from a multinomial distribution with probability vectors given by the rows of P kl . All confidence intervals reported for reproduction numbers are based on the quantiles of 1000 such simulations.