Papadaki M, Marmarinos A, Tsolia M, et al. - Researchers performed a prospective single pediatric tertiary care center cohort study to examine the correlation of serum vitamin D and nasal secretion antimicrobial peptides (AMPs) levels with the severity of acute bronchiolitis. The sample consisted of inpatients aged 0‐18 months with a first episode of acute bronchiolitis from November 1, 2014, to April 30, 2017. Participants in the study were 153 infants and toddlers with a median age of 3.1 months (IQR:1.6‐4.9). There was no connection found between serum 25(OH)D and AMPs nasal secretions levels. In hospitalized infants and toddlers, an important link between LL37 nasal secretions levels and the severity of acute bronchiolitis was discovered. Further research into the role of LL37 in the pathogenesis of bronchiolitis is required.