Could a common antibiotic ease severe wheezing in young children?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age 18 months to \<60 months. * The presence of expiratory wheezing as ascertained by a physician or nurse practitioner at admission to the ED. * A Pediatric Respiratory Assessment Measurement (PRAM) score of greater than or equal to 4 at any time during the ED admission. Exclusion Criteria: * Presence of acute infection that requires systemic antibiotics, as determined by the physician. * Current or previous use of systemic antibiotics within the last 2 weeks. * Current or previous use of a steroid for wheezing within the last 2 weeks. * Suspected foreign body induced aspiration during the last 2 weeks. * A known systemic illness (other than allergy) including but not limited to: * Recurrent seizures * Gastroesophageal reflux (GER) requiring medical treatment * Major congenital anomalies * Physical and intellectual delay * Cerebral palsy * A history of chest surgery * Tuberculosis or other chronic infections * Primary or secondary immunodeficiency * Gastrointestinal malformation or disease * Cardiac disorder (except for a hemodynamically insignificant atrial septal defect (ASD), ventricular septal defect (VSD) or benign heart murmur) * Born at less than 36 weeks estimated gestational age. * Received oxygen for more than 5 days in the neonatal period, or received invasive mechanical ventilation. * Significant developmental delay / failure to thrive, defined as a child plotting less than 3rd percentile. * Any chronic lung disease. * The study intervention poses undue risk to patient in the opinion of the treating physician * Known sensitivity or allergy to AZ. * Participation in the evaluation of a drug or medical device currently or within the last 30 days. * Previous enrollment into this trial. * Inability of the parent or guardian to speak English or Spanish. * Positive PCR or antigen test for COVID-19 from hospital/doctor's office/testing center within the past 30 days.