• In the influenza-related ARDS group, the levels of IL-6, IL-8, IL-9, IL-12, IL-15, IP-10 and TNFα are significantly increased versus the control group. In the bacterial sepsis-ARDS group, levels of IL-6, IL-8, IL-9, IL-15, IL-17, IP-10 and TNFα are also increased versus the control group. When comparing these two groups, the levels of IL-8, IL-17 and TNFα are significantly higher in bacterial ARDS versus viral ARDS, and IL-12 is increased only in viral ARDS whereas IL-17 is increased only in bacterial ARDS. When comparing the mild nvA (H1N1) and critical ARDS influenza A groups, IL-6, IL-8, IL-15 and TNFα are significantly higher in critical ARDS patients being hallmarks of disease severity.