• Patients ≥18 years of age

• Admitted to hospital for a suspected or confirmed diagnosis of CAP defined by:

‣ Radiographic evidence of new or worsening infiltrate

⁃ One or more of the following signs and/or symptoms of lower respiratory tract infection

• i. New or increased cough or sputum production ii. Fever of \> 37.8C or temperature \< 36C iii. WBC \> 11 x 109/L or \< 4 x 109/L c. The primary diagnosis is believed to be CAP as per the attending physician

• Requires supplemental oxygen to treat hypoxemia (or requires an increased level of supplemental oxygen if on chronic oxygen therapy)

• Hospital admission anticipated to last ≥72 hours from randomization