The results of the cytokine profile are shown in Figure  1 . At admission, only IL-6, IL-12, IP-10 and TNFα were significantly higher in the mild disease group than in the control group. Except for IL-17 and IFNγ, all cytokine levels were higher in critical patients with nvA (H1N1)-ARDS than in the control group. Compared with the mild disease group, significantly higher levels of IL-6, IL-8, IL-15 and TNFα were found in the nvA (H1N1)-ARDS group (P < 0.001, P < 0.001, P < 0.001 and P < 0.05, respectively). Compared with controls, the levels of IL-6, IL-8, IL-9, IL-15, IL-17, IP-10 and TNFα were significantly elevated in the bacterial sepsis-ARDS group. Levels of IL-8, IL-17 and TNFα were significantly higher in the bacterial-ARDS group versus the nvA (H1N1)-ARDS group (P = 0.05, P = 0.004 and P = 0.011, respectively; Figure 1 ).