Severe Influenza Trial of ARbidol

Inclusion criteria

• Hospitalized males or females with a positive antigen or PCR test for influenza virus infection
• Age ≥16 years at the time of signing Informed Consent Form
• Arterial oxygen saturation (SaO2)/ pulse oxygen saturation (SPO2) ≤94% in room air condition
• ≤ 7 days since symptom onset. The onset of symptoms is defined as either: Time of the first increase in body temperature (an increase of at least 1ºC from normal body temperature- ≥38℃); Time when the patient experiences at least one general or respiratory symptom.
• Willingness to use contraception for 7 days after the end of treatment

Exclusion criteria

• Physicians make a decision that trial involvement is not in patients' best interest, or any condition that does not allow the protocol to be followed safely.
• Patient refusal to accept invasive organ support treatment if needed
• More than 3 consecutive doses of NAIs within 2 days before enrolment (including oseltamivir, zanamivir, peramivir)
• Women who are pregnant (including a positive pregnancy test at enrolment), breastfeeding, or within 2 weeks post-partum.

The following female subjects do not need to undergo a pregnancy test at enrolment: a. Postmenopausal (defined as cessation of regular menstrual periods for 2 years or more and confirmed by a follicle-stimulating hormone test) women. b. Women who are surgically sterile by hysterectomy, bilateral oophorectomy, or tubal ligation.

• Any condition requiring renal replacement therapy
• Severe liver disease (Child-Pugh score ≥ C)
• A history of hypersensitivity to arbidol or oseltamivir (Tamiflu®)
• Currently or have been involved in another anti-influenza treatment trial in the last 28 days
• Patients who, in the opinion of the investigator, would be unlikely to comply with required study visits, self-assessments, and interventions