As noted above, model can be used to estimate turning points (t i ) and basic reproductive numbers (R 0 .), if the generation time T is know. We used T = 1.91 days (95% CI: 1.30-2.71), as obtained in [2] by fitting an age stratified mathematical model to the first recognized 2009 influenza A (H1N1) outbreak in La Gloria, Mexico. Estimates are presented in Table 1 . We also conducted sensitivity analyses with R 0 # calculated based on longer generation times (T = 3.6 (2.9, 4.3)) for seasonal influenza in [13] (see last column in Table 1 ). Excluding implausibly high estimates of R 0 generated using initial outbreak data (April 13 to May 15), we obtain the estimates of R 0 for the 2-phase model that range between 1.31 and 1.96. Inasmuch as Richards model analyzes the general trends of an epidemic (e.g., turning point, reproductive number, etc.), it can be used to fit any epidemiological time series for a given disease process, as long as the rate of change in the recorded outcome is proportional to changes in the true number of cases. As such, for comparison, we fit our model using the time series for 2009 pH1N1 hospitalizations in Canada posted by PHAC on July 15 [11] (that last date these data were made available) ( Table 3) . This time series was easily fit to a one-phase model ( Figure 2) . Further examples of using hospitalization or mortality data to fit the Richards model can be found in [14] .