Innovative Steroid Treatment to Reduce Asthma Development in Children After First-time Rhinovirus Induced Wheezing

Inclusion Criteria: * admitted to pediatric acute wards in the participating hospitals in Norway, Finland, Sweden. * referred for first severe wheezing episode, defined as first-time acute breathing difficulty with wheezing ever, appearing less than 7 days from onset of symptoms * one or more of the following:(a) fever, (b) hypoxia (SAT O2 \<= 92%), (c) retractions (inter-, subcostal), (d) prolonged expiration (on auscultation), (e) expiratory rhonchi (on auscultation) * evidence of rhinovirus infection by PCR-test in nasopharyngeal secretions * signed informed consent and expected cooperation of the patients for the treatment and follow-up must be obtained and documented according to ICH GCP, and national/local regulations. Exclusion Criteria: * previous episodes with wheezing, defined as a history of acute breathing difficulty with wheezing in need of treatment at a general practitioner or at hospital, or parental information about similar breathing difficulties * gestational age \<37 weeks * chronic illness other than atopy (eczema), * previous systemic or inhaled corticosteroid treatment, * participation to another trial, * varicella infection or contact during the last 2-3 weeks, * need for intensive care unit treatment during the present infection, except for respiratory support with non-invasive methods (high flow nasal cannula ventilation, CPAP or BiPAP), * any reason why, in the opinion of the investigator, the patient should not participate (e.g. not able to comply with study procedures). * COVID-19 related disease.