Initial serum levels of cytokines in the four groups. The Mann-Whitney U test was used to compare cytokine levels: (A) IL-6. (B) IL-8. (C) IL-9. (D) IL-12. (E) IL-15. (F) IL-17. (G) interferon-inductible protein-10 (IP-10). (H) IFNγ. (I) TNFα. Data presented as median, quartiles, and range. ARDS, acute respiratory distress syndrome; nvA(H1N1), novel A(H1N1) virus.