This is a study to evaluate the efficacy and safety of a single dose of intravenous peramivir versus placebo in adolescents and adults with acute uncomplicated influenza.

This is a multicenter, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of a single dose of intravenous peramivir versus placebo in adolescents and adults with acute,uncomplicated influenza.

Inclusion Criteria:

• Male and non-pregnant female subjects age ≥12 years.
• Test positive for influenza A or B by Rapid Antigen Test (RAT) performed with a commercially available test on an adequate anterior nasal specimen in accordance with the manufacturer's instructions.
• Presence of at least one respiratory symptom (cough, sore throat, or nasal symptoms) of at least moderate severity.
• Presence of at least one constitutional symptom (myalgia [aches and pains], headache,feverishness, or fatigue) of at least moderate severity.
• Onset of symptoms no more than 36 hours before presentation for screening.
• Written informed consent/assent.

Exclusion Criteria:

• Women who are pregnant or breast-feeding.
• Employees of the study site, or immediate family members of study site employees.
• Presence of clinically significant signs of acute respiratory distress.
• History of severe chronic obstructive pulmonary disease (COPD) or severe persistent asthma.
• History of heart failure or angina requiring daily pharmacotherapy with symptoms consistent with New York Heart Association Class III or IV functional status within the past 12 months.
• History of chronic renal impairment requiring hemodialysis and/or known or suspected to have moderate or severe renal impairment (actual or estimated creatinine clearance <50 mL/min).
• Clinical evidence of worsening of any chronic medical condition (temporally associated with the onset of symptoms of influenza) which, in the investigator's opinion, indicates that such finding(s) could represent complications of influenza.
• Current clinical evidence, including clinical signs and/or symptoms consistent with otitis media,bronchitis, sinusitis and/or pneumonia, or active bacterial infection of any body site that requires therapy with oral or systemic antibiotics.
• Presence of immunocompromised status due to chronic illness, previous organ transplant, or use of immunosuppressive medical therapy which would include oral or systemic treatment with > 10 mg ic treatment with > 10 mg prednisone or equivalent on a daily basis within 30 days of screening.
• Presence of known HIV infection with a CD4 count <350 cell/mm3.
• Receipt of any dose of rimantadine, amantadine, zanamivir, or oseltamivir in the 7 days prior to screening.
• Immunization against influenza with live attenuated virus vaccine (FluMist®) in the previous 21 days.
• History of alcohol abuse or drug addiction within 1 year prior to admission in the study.
• Participation in a previous study of intramuscular or intravenous peramivir, or previous exposure to peramivir.
• Participation in a study of any investigational drug or device within the last 30 days.
• Presence of any pre-existing illness that, in the opinion of the investigator, would place the subject at an unreasonably increased risk through participation in this study.
• Presence of any pre-existing illness that in the opinion of the investigator would make the subject unable to comply with the protocol.