Procedures
Medical records of all patients accepted to the emergency department were reviewed. We collected the following variables: age, sex, weight, height, signs, and symptoms on admission (including fever, chest in-drawing, chest auscultation, %SpO2), vaccination scheduled chart for age, current exposure (maternal or paternal) to cigarette smoking, history of prematurity and bronchopulmonary dysplasia confirmed by a neonatologist upon discharge from NICU, comorbidities (congenital heart disease, neurological disease), diagnostic tools such as chest X-rays, etc. In our hospitals, bronchodilators and systemic steroids are used at the discretion of attending physicians according to national clinical bronchiolitis guidelines(9). Nasopharyngeal aspirate was taken immediately upon admission to the emergency department within 48 hours of admission using a standard technique. RSV was confirmed using direct immunofluorescence (Light Diagnostics TM Respiratory Panel 1 DFA, Merck-Millipore Laboratory).