Clinical Study to Evaluate Antibody and Cell Mediated Immunity of A/H1N1 Influenza Vaccine in Healthy Subjects

Inclusion Criteria: * Written informed consent obtained; * Males and females from 18 years to 60 years of age on the day of enrolment; * Subjects in good health as determined by the outcome of medical history, physical assessment and clinical judgment by the Investigator; * Subjects are able to comply with all study procedures and are available for all clinic visits scheduled in the study; * Willingness to allow for blood samples to be stored beyond the study period, for potential additional future testing to better characterize immune response. Exclusion Criteria: * Subjects who are not able to comprehend and to follow all required study procedures for the whole period of the study; * Subjects 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; * Subjects with any serious chronic or progressive disease according to judgment of the Investigator (including, but not limited to malignant neoplasm, insulin dependent diabetes, cardiac, renal or hepatic disease); * History of any anaphylaxis, serious vaccine reactions, or hypersensitivity to influenza viral proteins, to any excipients, and to eggs (including ovalbumin), and chicken proteins; * Subjects who have had seasonal influenza vaccine or documented confirmed seasonal influenza disease within 2 weeks prior to Day 1; * Receipt of another investigational agent within 4 weeks prior to enrolment, or before completion of the safety follow-up period in this or in another study; subjects unwilling to refuse participation in another clinical study throughout the end of this study; * Subjects who received any other vaccines within 4 weeks prior to enrolment in this study or who are planning to receive any vaccine within 4 weeks from the study vaccines; the only exception being plain seasonal influenza vaccines which are allowed until 2 weeks before and over 2 weeks after the study vaccination; * Subjects who have received blood, blood products and/or plasma derivatives or any parenteral immunoglobulin preparation in the past 12 weeks or plan to receive these products during the full length of the study; * Subjects with axillary temperature ≥ 38°C (≥ 100.4°F) or oral temperature ≥ 38.5°C (≥ 101.3°F) within 3 days of intended study vaccination; * Known or suspected impairment/alteration of immune function, for example resulting from: 1. receipt of immunosuppressive therapy such as systemic corticosteroids known to be associated with the suppression of hypothalamic-pituitary-adrenal (HPA) axis (10 mg/day of prednisone or its equivalent) or chronic use of inhaled high-potency corticosteroids (e.g. budesonide 800µg/day or fluticasone 750µg/day) within 60 days prior to Visit 1, 2. cancer chemotherapy within 5 years, 3. receipt of immunostimulants within 60 days prior to Visit 1, 4. history of HIV infection or HIV-related disease; * History of progressive or severe neurological disorders (including Guillain-Barré syndrome and convulsions, but excluding febrile convulsions); * History of or clinically suspected developmental delay; * Bleeding diathesis; * Surgery planned during the study period that in the Investigator's opinion would interfere with the study; * Female subjects who are pregnant or nursing (breastfeeding) mothers, or females of childbearing potential who are sexually active and have not used any of the "acceptable contraceptive methods" for the 2 months before entering the study or do not plan to use them up to the end of the study; * Members of the research staff who have direct access to any study documents containing subject information.