Azithromycin Treatment for Respiratory Syncytial Virus-induced Respiratory Failure in Children

Inclusion criteria: * Admission to the pediatric ICU with a confirmed diagnosis of RSV infection. RSV infection is based on a positive nasal swab for RSV fluorescent antibody or via multiplex assay or culture; * Requiring intensive respiratory support defined as either mechanical ventilation or NIV (BiPAP or CPAP) or HFNC (at \>1 L/kg/min of flow * Enrollment into the study within 48 hours of ICU admission and placement on intensive respiratory support; * Onset of RSV-related symptoms must be less than 5 days * Age: Neonates-2 years. For those less than 1 week of age, they must have been discharged home from the hospital after their birth. Exclusion criteria: * AZM use within 7 days of ICU admission; * Contraindication to AZM use including known hypersensitivity to AZM, erythromycin, any macrolide, or ketolide drug, patients with significant hepatic impairment (direct bilirubin \>1.5 mg/dL or ALT ≥ 10 times the upper limits of normal); * Patients with known cardiac disease, cardiac arrhythmia or with electrocardiogram QT interval corrected for heart rate (QTc) ≥ 450 milisecond (ms); * Intensive respiratory support greater than 48 hours prior to ICU admission; * Chronic ventilation or supplemental oxygen need at home; * Immunosuppressive conditions such as those post heart or hematopoietic stem cell transplant or receiving chemotherapy and chronic steroids; * History of pyloric stenosis; * AZM is deemed necessary for clinical treatment (for instance, if patient has pertussis).