We used the observed time series of new cases of human H5N1 influenza DT(t) to compute the probability distribution for R using programs implemented both in Matlab and Fortran. We used an unbiased uniform distribution for R between 0 and 3 as the initial prior. For each subsequent weekly iteration, we computed the full posterior distribution from [13] using the posterior at the previous week as the new prior. The product of the two probabilities on the right-hand side of [13] was evaluated as a non-parametric function defined in terms of 1000 discrete bins in R between 0 and 3, as shown in Figure S3 in the Supplementary Material S1. Parameters choices used in the calculations in the main text are: t = 1 week, c = 1 week 21 , h variable as in Table 1 . We also explored other parameter choices reported in the literature for seasonal influenza and corresponding results are given in Table S1 of Supplementary Material S1.