Notably, when compared with the seasonal influenza group, the Th1-related CXCL10/IP-10 and CXCL9/MIG, and the Th17-related IL-17A were markedly suppressed in cases of severe pH1N1 pneumonia (2–27 times lower; P−values <0.01). This evidence concerns the gene IL17A and susceptibility to pneumonia measurement.