Isotonic Saline for Children With Bronchiolitis

The goal of this randomized clinical trial is to investigate the optimal supportive treatment of bronchiolitis in infants from 0-12 months of age. The main question\[s\] it aims to answer are: * To investigate whether isotonic saline should be used as supportive treatment for children with bronchiolitis, and if so, identify the optimal route of administration. The primary outcome is duration of hospitalization. * To investigate the current epidemiology of the viral pathogens causing bronchitis in children in Denmark, and to assess whether children infected with specific pathogens might benefit from treatment with isotonic saline. The children are randomized after inclusion through computer randomization to one of the 3 arms in the study: 1. Nebulized isotonic saline 2. Nasal irrigation with isotonic saline 3. No treatment with saline The investigators will compare treatment with saline (both methods) with no treatment, and the investigators will also compare the two methods of delivery of saline (nebulized vs. nasal irrigation).