Thorsen J, Stokholm J, Rasmussen MA, et al. - Researchers conducted this randomized clinical trial for analyzing the influence of the airway microbiota on the effect of azithromycin treatment during acute episodes of asthma-like symptoms. As previously reported, children from the Copenhagen Prospective Studies on Asthma in Childhood 2010 cohort with recurrent asthma-like symptoms aged 12–36 months were randomized to azithromycin or placebo during acute episodes. In preschool children with recurrent asthma-like symptoms, the airway microbiota is associated with episode duration and modifies the effect of azithromycin treatment.