Inclusion Criteria:

• Adult volunteers in good health aged over 18 years, both sexes;
• Full contractual capacity of the partcipants;
• Are in good health (as determined by vital signs and medical history);
• Negative urine or serum pregnancy test for females of childbearing potential;
• Are able to understand and comply with planned study procedures;
• Signed informed consent prior to initiation of study procedures;
• Absence of existence of any exclusion criteria.

Exclusion Criteria:

• Known allergy to eggs or other components of the vaccine;
• History of Guillain-Barré syndrome;
• Pregnancy or breast feeding or positive pregnancy test prior to vaccination;
• Immunosuppressive therapy in the preceeding 36 months;
• Active neoplasm (i.e. requiring any form of anti-neoplastic therapy);
• Concomitant corticosteroid therapy, including inhaled corticosteroids;
• Psychiatric illness and/or concomitant psychiatric drug therapy;
• Immunoglobulin (or similar blood product) therapy within 3 months prior to vaccination;
• Vaccine therapy within 4 weeks prior to the study;
• Influenza vaccination within 6 months prior to the study;
• Chronic illness that, in the opinion of the investigator, may interfere with the evaluation of the immune response;
• Documented HIV, HBV or HCV infection;
• Acute febrile respiratory illness within one week prior to vaccination;
• Experimental drug therapy within 1 month prior to vaccination;
• Alcohol or drug abuse.