Influenza poses a significant threat to individual and public health, and influenza vaccination with a trivalent inactivated influenza vaccine is widely recommended to children, adults at risks and elderly. Due to antigenic changes of influenza viruses, the virus strains used in interpandemic influenza vaccines are adjusted every year according to WHO (World Health Organization) and CHMP (Committee for Medicinal Products for Human Use) recommendations. Following a change in the vaccine antigen composition recommendation from the previous season, immunogenicity and tolerability of the newly composed vaccines are subject of evaluation in an annual clinical trial in non-elderly adult and elderly subjects according to the guidelines set by EMEA (CPMP/BWP/214/96).

Inclusion Criteria:

1. Male and female volunteers of 18 years of age and older, mentally competent, willing and able to give written informed consent prior to study entry;
2. Individuals able to comply with all the study requirements;
3. Individuals in good health as determined by medical history, physical examination and clinical judgment of the investigator.

Exclusion Criteria:

1. Individuals with behavioral or cognitive impairment or psychiatric disease that, in the opinion of the investigator, may interfere with the subject's ability to participate in the study;

2. Individuals with any serious chronic or acute disease (in the judgment of the investigator), including but not limited to:

   1. Cancer, except for localized skin cancer;
   2. Advanced congestive heart failure;
   3. Chronic obstructive pulmonary disease (COPD);
   4. Autoimmune disease (including rheumatoid arthritis);
   5. Acute or progressive hepatic disease;
   6. Acute or progressive renal disease;
   7. Severe neurological or psychiatric disorder;
   8. Severe asthma;

3. Individuals with history of any anaphylactic reaction and/or serious allergic reaction following a vaccination, a proven hypersensitivity to any component of the study vaccine (e.g. to ovalbumin, chicken protein, chicken feathers, influenza viral protein, polymyxin, neomycin);

4. Individuals with known or suspected (or have a high risk of developing) impairment/alteration of immune function (excluding that normally associated with advanced age) resulting, for example, from:

   1. receipt of immunosuppressive therapy (any parenteral or oral corticosteroid or cancer chemotherapy/radiotherapy) within the past 60 days and for the full length of the study;
   2. receipt of immunostimulants;
   3. receipt of parenteral immunoglobulin preparation, blood products and/or plasma derivates within the past 3 months and for the full length of the study;
   4. suspected or known HIV infection or HIV-related disease;

5. Individuals with known or suspected history of drug or alcohol abuse;

6. Individuals with a bleeding diathesis or conditions associated with prolonged bleeding time that in the investigator's opinion would interfere with the safety of the subject;

7. Female who are pregnant or nursing (breastfeeding) mothers or females of childbearing age do not plan to use acceptable birth control measures, for the duration of the study. Adequate contraception is defined as hormonal (e.g., oral, injection, transdermal patch, implant, cervical ring), barrier (e.g., condom with spermicide or diaphragm with spermicide), intrauterine device (IUD), or monogamous relationship with vasectomized partner who has been vasectomized for 6 months or more prior to the subject's study entry;

8. Individuals who are not able to comprehend and to follow all required study procedures for the whole period of the study;

9. Individuals that within the past 12 months have received more than one injection of influenza vaccine;

10. Individuals that within the past 6 months have:

    1. had laboratory confirmed seasonal or pandemic influenza disease;
    2. received seasonal or pandemic influenza vaccine;

11. Individuals with any acute or chronic infections requiring systemic antibiotic treatment or antiviral therapy within the last 7 days;

12. Individuals that have experienced fever (i.e., axillary temperature ≥38°C) within the last 3 days of intended study vaccination;

13. Individuals participating in any clinical trial with another investigational product 4 weeks prior to first study visit or intent to participate in another clinical study at any time during the conduct of this study;

14. Individuals who received any other vaccines within 4 weeks prior to enrollment in this study or who are planning to receive any vaccine within 4 weeks from the study vaccines;

15. Individuals who have received blood, blood products and/or plasma derivatives or any parenteral immunoglobulin preparation in the past 12 weeks and for the full length of the study;

16. Individuals who are part of study personnel or close family members conducting this study;

17. Individuals with history or any illness that, in the opinion of the investigator, might interfere with the results of the study or pose additional risk to the subjects due to participation in the study;

18. BMI > 35 kg/m2.