Safety and Immunogenicity of 3 Lots of Cell-derived Subunit Influenza Vaccine as Compared to 1 Lot to Egg-derived Subunit Influenza Vaccine in Healthy Adults (>=18 to <=60)

Inclusion Criteria:

1. 18 to <61 years of age
2. mentally competent to understand the nature, the scope and the consequences of the study
3. able and willing to give written informed consent prior to study entry

4. in good health as determined by:

   1. medical history,
   2. physical examination,
   3. clinical judgment of the Investigator.

Exclusion Criteria:

1. unwilling or unable to give written informed consent to participate in the study
2. participation in another clinical trial of an investigational agent within 90 days prior to Visit 1 and throughout the entire study
3. currently experiencing an acute infectious disease

4. any serious disease, such as, for example:

   1. cancer,
   2. autoimmune disease (including rheumatoid arthritis),
   3. advanced arteriosclerotic disease or complicated diabetes mellitus,
   4. chronic obstructive pulmonary disease (COPD) requiring oxygen therapy,
   5. acute or progressive hepatic disease,
   6. acute or progressive renal disease,
   7. congestive heart failure
5. surgery planned during the study period
6. bleeding diathesis
7. history of hypersensitivity to any component of the study medication or chemically related substances
8. history of any anaphylaxis, serious vaccine reactions, or allergy to any of the vaccine component

9. known or suspected impairment/alteration of immune function, for example resulting from:

   1. receipt of immunosuppressive therapy (any corticosteroid therapy or cancer chemotherapy),
   2. receipt of immunostimulants,
   3. receipt of parenteral immunoglobulin preparation, blood products, and/or plasma derivates within 3 months prior to Visit 1 or planned during the full length of the study,
   4. high risk for developing an immunocompromising disease
10. history of drug or alcohol abuse
11. laboratory-confirmed influenza disease within 6 months prior to Visit 1
12. receipt of influenza vaccine within 6 months prior to Visit 1
13. receipt of another vaccine within 60 days prior to Visit 1, or planned vaccination within 3 weeks following study vaccination
14. any acute respiratory disease or infections requiring systemic antibiotic or antiviral therapy (chronic antibiotic therapy for urinary tract prophylaxis is acceptable) or experienced fever (i.e., axillary temperature ≥ 38 degree C) within 5 days prior to Visit 1
15. if female, pregnant or breastfeeding
16. if female, refusal to use a reliable contraceptive method during the three weeks following vaccination
17. planned relocation abroad during the study period
18. any condition that, in the opinion of the Investigator, might interfere with the evaluation of the study objectives.