['influenza, human']
['celecoxib', 'oseltamivir', 'placebo']

        Inclusion Criteria:

        1) Male or female patients ≥18 years 2) Written informed consent by patient or next-of kin
        (if patient is too ill to consent) 3) Presumptive diagnosis of influenza A satisfying both
        clinical and laboratory criteria. The laboratory criteria are defined as at least one
        RT-PCR positive for influenza A (H1N1, H3N2, H5N1 and H7N9) from respiratory clinical
        specimens including nasopharyngeal samples and endotracheal aspirates. The clinical
        criteria are defined as hospitalization with fever or one of the symptoms suggestive of
        influenza infection including sore throat, rhinorrhea, cough or shortness of breath 2)
        Desaturation to <90% in room air by pulse oximetry and required oxygen supplement 3) Within
        7 days of onset of symptoms. Patients have to fulfil all the aforementioned criteria.

        Exclusion Criteria:

        1) Age <18 years. 2) A known hypersensitivity to celecoxib, oseltamivir or zanamivir 3)
        Unable to obtain informed consents 4) Influenza A infection diagnosed beyond 7 days from
        symptom onset 5) Patients receiving other antiviral treatment (apart from oseltamivir or
        zanamivir), N-acetylcystiene, statins and tradition Chinese medicine during the current
        admission 6) Patients with renal impairment of creatinine clearance < 30mL/min
      