Tang HHF, Lang A, Teo SM, et al. - This study was undertaken to determine if developmental trajectories of the nasopharyngeal microbiome in early life and the composition of the microbiome during illnesses were related to the risk of childhood asthma. In the first two years of life, children partaking in the Childhood Origins of Asthma study (n = 285) provided nasopharyngeal mucus samples, during routine healthy study visits (2, 4, 6, 9, 12, 18 and 24 months of age) and episodes of respiratory illnesses, which were analyzed for respiratory viruses and bacteria. Of the four microbiome trajectories identified, a Staphylococcus-dominant microbiome in the first 6 months of life has been correlated with increased risk of recurrent wheezing by age 3 years and asthma that persisted throughout childhood. This trajectory was also associated with the early onset of allergic sensitization. During wheezing illnesses, detection of rhinoviruses and predominance of Moraxella were linked to asthma that persisted throughout later childhood. The developmental composition of the microbiome during healthy periods in infancy and the predominant microbes during acute wheezing illnesses are both related to the subsequent risk of developing persistent childhood asthma.