The lymphocyte count was significantly lower in the nvA(H1N1)-ARDS group than in the mild disease group (P = 0.011) ( Table 2 ). Comparing laboratory abnormalities on hospital admission we found that patients with nvA(H1N1)-ARDS were more likely to have elevated levels of serum lactate dehydrogenase, alanine and aspartate aminotransferase (P < 0.001, P = 0.049 and P < 0.001, respectively) than patients with nvA(H1N1)mild disease ( Table 2) .