Background and clinical characteristics of study subjects.

*Wheezing was defined as a continuous high pitched sound emitting from the chest during expiration on auscultation.†Pneumonia was diagnosed on the basis of infiltrative shadows on chest radiograph.‡Asthma includes active asthma and inactive asthma.§Other comorbidities include smoking , alcoholism, diabetis meritis, chronic heart diseases , obesity.¶SpO2: oxygen saturation measured by pulse oximetry in room air.∥Pathogenic bacteria co-infection was detected by throat swabs and/or sputum.Definition of abbreviations: WBC, white blood cell count; LDH, lactate dehydrogenase; ALP, alkaline phosphatase; AST, aspartate amino transferase; ALT, alanine aminotransferase; CRP, C-reactive protein; IgE, Immunoglobulin E.