Safety and Immunogenicity of a Subunit Trivalent Nonadjuvated Influenza Study Vaccine in Adults Aged 18 Years and Above

Inclusion Criteria: 1. Male and female volunteers of 18 years of age or older; 2. Individuals able to comply with all the study requirements; 3. Individuals in good health as determined by the outcome of 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, could have interfered 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: * Medically significant cancer (except for benign or localized skin cancer, cancer in remission for ≥10 years or localized prostate cancer that has been clinically stable for more than 2 years without treatment); * Medically significant advanced congestive heart failure (ie. NYHA class III and IV); * Chronic obstructive pulmonary disease (COPD; i.e., GOLD Stage III and IV); * Autoimmune disease (including rheumatoid arthritis, except for Hashimoto's thyroiditis that has been clinically stable for ≥5 years); * Diabetes mellitus type I; * Poorly controlled diabetes mellitus type II; * Advanced arteriosclerotic disease; * History of underlying medical condition such as major congenital abnormalities requiring surgery, chronic treatment, or associated with developmental delay (e.g., Down's syndrome); * Acute or progressive hepatic disease; * Acute or progressive renal disease; * Severe neurological (es. Guillain-Barré syndrome) or psychiatric disorder; * 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 eggs or eggs product as well as ovalbumin, chicken protein, chicken feathers, influenza viral protein, kanamycin and neomycin sulphate). 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: * 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; * receipt of immunostimulants; * receipt of parenteral immunoglobulin preparation, blood products and/or plasma derivates within the past 3 months and for the full length of the study; * 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 could have interfered with the safety of the subject. 7. Individuals who were not able to comprehend and to follow all required study procedures for the whole period of the study. 8. Individuals with history or any illness that, in the opinion of the investigator, posed additional risk to the subjects due to participation in the study. 9. Individuals who within the past 6 months have: * had any laboratory confirmed seasonal or pandemic influenza disease; * received any seasonal or pandemic influenza vaccine. 10. Individuals who received any other vaccine within 4 weeks prior to enrollment in this study or who were planning to receive any vaccine during the study. 11. Individuals with any acute or chronic infections requiring systemic antibiotic treatment or antiviral therapy within the last 7 days. 12. Individuals who 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 were part of study personnel or close family members conducting this study. 15. BMI \>35 kg/m2. 16. Females who were pregnant (confirmed by positive urine pregnancy test) or nursing (breastfeeding). Females of childbearing potential who refused to use an acceptable method of birth control for the whole duration of the study.