The purpose of this study is to compare the efficacy and safety of BCT197 when added on to standard of care in adult subjects with acute respiratory exacerbations of chronic obstructive pulmonary disease requiring hospitalization. Additionally, the study will characterize the pharmacokinetics of BCT197 in adults with COPD. The total duration of the study will be 26 weeks. Subjects will receive study treatment administration over a period of 5 days after randomization. It is expected that approximately 255 subjects will complete the study and follow-up.