The purpose of this study is to assess the safety and immunogenicity of three seasonal trivalent influenza vaccines (TIVs)manufactured by Glaxosmith Kline (GSK), Beijing Sinovac Biotech (Sinovac) and Shenzhen Sanofi Pasteur (Pasteur) in Chinese healthy servicemen. Using imported GSK's TIV as control, to compare it with other two domestic TIVs in Chinese healthy servicemen.

This study is a 1:1:1 randomized, double-blinded, controlled phase Ⅳ clinical trial in a military command in Beijing. Healthy individuals aged between 18～34 years who had not received any influenza vaccine during recent three years will be enrolled and administrated one dose TIV. Safety data will be collected for whole study (Day 0 to Day 30).Blood samples will be collected for immunogenicity assessments before injection and 21 days after vaccination.

Inclusion Criteria:

• Healthy servicemen aged between 18-34 years ,who had not received any influenza vaccine during recent three years;
• Proven legal identity;
• Written informed consent;
• Complying with the requirement of the study protocol;

Exclusion Criteria:

• Pregnant, breast feeding women;
• History of allergy to any vaccine or vaccine ingredient;
• Receipt of any immunosuppressant within 6 month prior to study entry;
• Congenital malformation, developmental disorders, serious chronic diseases, autoimmune disease, immunodeficiency, serious cardiovascular disease, diabetes, Guillain-Barré syndrome, hypertension that cannot be stabilized by medication, liver or kidney disease, or malignant tumor;
• Acute disease or acute stage of chronic disease within 7 days prior to study entry;
• Axillaty temperature > 37.0 °C;
• Any other factor that in the opinion of the investigator suggesting the volunteer is unsuitable for this study;