The purpose of this study is to evaluate the antibody response to each of the three influenza vaccine strains included in the seasonal flu vaccine(AdimFlu-S), as measured by hemagglutination inhibition (HAI) at 4 weeks after two doses of study vaccine, 4 weeks apart, in infants between 6 and 12 months of age.

Inclusion Criteria:

• Boys or girls and aged >= 6 months old to <= 12 months old on the day of first vaccination;
• Subject's parent(s) or legal guardian(s) must be willing to comply with planned study procedures and be available for all study visits;
• Subject must be in good physical health on the basis of medical history, physical examination;
• Subject's parent(s) or legal guardian(s) must read and signed the study-specific informed consent prior to initiation of any study procedure.

Exclusion Criteria:

• Subjects had received influenza vaccine;
• History of hypersensitivity to eggs or egg protein or similar pharmacological effects to study medication;
• Personal or family history of Guillain- Barre' Syndrome;
• An acute febrile illness within 1 week prior to vaccination;
• Current upper respiratory illness (URI), including the common cold or nasal congestion within 72 hours;
• Subjects with influenza-like illness as defined by the presence of fever (temperature >= 38'C) and at least two of the following four symptoms: headache, muscle/joint aches and pains (e.g. myalgia/arthralgia), sore throat and cough;Treatment with an investigational drug or device, or participation in a clinical study, within 3 months before consent;
• Immunodeficiency, immunosuppressive or significant chronic illness not suitable for inactivated influenza vaccination;
• History of wheezing or bronchodilator use within 3 months prior to study vaccine;
• Receipt of live virus vaccine within 1 month prior to study vaccine or expected receipt vaccination before the last blood sampling for immunogenicity evaluation;
• Receipt of any inactivated vaccine within 2 weeks prior to study vaccination or expected receipt vaccination before the last blood sampling for immunogenicity evaluation;
• Receipt of any blood products, including immunoglobulin in the prior 3 months;
• Underlying condition in the investigators' opinion may interfere with evaluation of the vaccine.