Re-licensing Study to Assess Virosomal Influenza Vaccine Formulated With WHO Recommended Influenza Strains

Inclusion Criteria: * Healthy female and male adults aged ≥18 on Day 1 * 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 * Acute febrile illness (≥38.0 °C) * Prior vaccination with an influenza vaccine in the past 330 days * Known hypersensitivity to any vaccine component * Previous history of a serious adverse reaction to influenza vaccine * 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), cancer * Investigational medicinal product received in the past 3 months (90 days) starting from the first day of the month following the last visit in a previous study * Treatment with immunoglobulins or blood transfusion(s) received in the past 3 months (90 days) * Pregnancy or lactation * Participation in another clinical trial * Employee at the investigational site, or relative of the investigator * Subjects who in the view of the investigator will not comply with study procedures and/or visit requirements as per protocol