The study is to assess whether the influenza vaccine Inflexal V for season 2013/2014 fulfills the EMA requirements for re-registration of influenza vaccines.

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)
• 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