Patients with pandemic influenza virus (severe ARDS and mild disease) were stratified according to the interval between symptom onset and admission. Levels of IL-6, IL-8, IL-15 and IFNγ were significantly higher in patients with delayed admission, > 5 days after symptom onset (P = 0.006, P = 0.037, P = 0.013 and P = 0.027, respectively) ( Table 3 ).