Efficacy and Safety of Inhaled Zanamivir in Treatment of Influenza A and B Virus Infections in China

Inclusion Criteria: * Who had fever (\>38.0ºC) * At least two of the following symptoms: chills, headache, myalgia, fatigue, nasal symptoms, sore throat, cough * Started therapy within 48 hours of onset of influenza-like illness * Written informed consent Exclusion Criteria: * Respiratory diseases, such as asthma or COPD * Woman with a positive urine pregnancy test * Woman without contraception during the study * Allergic to zanamivir, Paracetamol or lactose * WBC ≥ 10.5×109/L; neutrophil percentage ≥ 80% * Hepatic function impairment: AST ≥ 2×ULN, ALT ≥ 2×ULN * Renal function impairment: Cr \> 221μmol/L * Influenza vaccination in the 12 months prior the beginning of the study * History of tumor, psychiatric disorders, epilepsy or drug abuse * Patients receiving corticosteroids, immunosuppressants * HIV positive