Timeline depicting longitudinal changes in butyrate-producing bacteria abundance and viral LRTI events following engraftment. Patients are sorted into 3 groups, depending on the abundance of butyrate-producing bacteria in the engraftment sample (triangle). For the most part, abundances were high at the start of allo-HCT, but declined as antibiotics (green lines) were administered. Viral lower respiratory tract events are depicted with their associated respiratory viruses by the purple lines following engraftment. Adeno, adenovirus; Corona, coronavirus; FluA, influenza virus type A; FluB, influenza virus type B; Metapneumo, human metapneumovirus; Paraflu1, parainfluenza virus type 1; Paraflu3, parainfluenza virus type 3; Rhino, rhino-/enterovirus; RSV, respiratory syncytial virus.