The causes of readmissions were ES (n = 3) and respiratory syncytial virus (RSV) pneumonia (n = 1) in group A; ES (n = 1) and RSV pneumonia in group B; and human metapneumovirus infection (n = 1) in group C. In the multivariate analysis for hospital readmission, age ≥ 60 years was a risk factor (OR 14.6; P = 0.04); meanwhile, the avoidance of G-CSF with the administration of corticosteroid retained an independent protective factor (OR 0.07; P = 0.05) (Table 3). Here, CSF3 is linked to susceptibility to pneumonia measurement.