Percentage distributions of fatal cases of influenza–pneumonia during 1918–19 influenza pandemics, by estimated days of illness before death. A) Influenza–bronchopneumonia, Cook County Hospital, Chicago, Illinois, USA (n = 599) (estimated from chart 2 in [19]). B) Australian Imperial Forces, 1918 (n = 972) (G.D. Shanks, unpub. data). C) General population, Prussia (n = 6,223) (22). D) US Army autopsy series (n = 94) (estimated from supplementary Figure 2 in [17]). E) Influenza with secondary staphylococcal pneumonias, Fort Jackson, South Carolina, USA (n = 153) (interpolation of data in Table 1 in [21]). F) New South Wales, Australia (n = 3,866) (20). G) US Army training camp, Camp Pike, Arkansas, USA (n = 234) (5). Horizontal bars indicate interquartile ranges; vertical lines indicate medians.