Clinical Study for Safety and Immunogenicity Study of Influenza Vaccine

Inclusion Criteria: * Healthy male and female adults * Aged ≥ 18 to ≤ 50 years on the day of enrollment * Written informed consent * Female subjects of childbearing potential using and willing to continue using an acceptable method of contraception unless surgically sterilized/hysterectomized or post-menopausal for more than 2 years Exclusion Criteria: * Acute exacerbation of bronchopulmonary infection (cough, sputum, lung findings) or other acute disease * Body weight below 40 kg at any visit during the study * Acute febrile illness (≥ 38.0°C) * Known hypersensitivity to any vaccine component * Previous history of a serious adverse reaction to influenza vaccine * Previous vaccination with a seasonal influenza vaccine for season 2011-2012 or a virosomal formulation of seasonal influenza vaccine in any season * History of egg protein allergy or severe atopy * Known blood coagulation disorder * Chronic (longer than 14 days) administration of immunosuppressants or other immune-modifying drugs within 6 months before the first dose of the study vaccine, including oral corticosteroids in dosages of ≥ 0.5 mg/kg/d prednisolone or equivalent (inhaled or topical steroids are allowed) * Known immunodeficiency (incl. leukemia, HIV seropositivity) or cancer * Known history of psychiatric diseases, particularly dementia * Investigational medicinal product received in the past 3 months (90 days) * Treatment with immunoglobulins or blood transfusion(s) received in the past 3 months (90 days) * Pregnancy or lactation * Participation in another clinical trial for the entire duration of this trial * Employee at the investigational site or relative of the investigator * Subjects who in the view of investigator will not comply with study procedure and/or visit requirements as per protocol