Fig. 4

Summary of household infection data and estimates of the parameters for influenza types. a. Type A and b. type B (bottom row). The left column shows the histogram of the symptomatic period and its fitting to a gamma distribution. The middle column shows the histogram of the serial interval, its fitting to the distribution constructed as a convoluted gamma distribution (blue curve), and the extracted infectious period (annotation) and incubation period (red curve) via the fitting (see the Methods section for detail). The right column shows the negative likelihood against the assumed infective period