Safety and Immunogenicity of GPO Seasonal Tetravalent Inactivated Split Virion Influenza Vaccine in Healthy Thais

Inclusion Criteria: Aged 18 years and above Having Thai ID card or equivalent Able to read and provide written informed consent prior to performance of any study-specific procedure Healthy as defined by no clinically significant acute medical condition, and no chronic medical condition that has not been controlled within 90 days of randomization, as determined by medical history, physical examination, screening laboratory test results, and clinical assessment of the investigator. All hematology, biochemistry and urine analysis are within normal range or of no clinical significance (not higher than 1.5 time of normal value without any clinical finding from history and physical examination) Exclusion Criteria: Known history of egg allergy Having had recently influenza infection confirmed as H1N1, H3N2, or Flu B within 3 months preceding enrollment to the trial Vaccination against influenza in the past 6 months preceding enrollment to the trial History of bronchial asthma, chronic lung diseases, chronic rhinitis History of immunodeficiency state History of immunosuppression < 6 months prior to immunization History of anaphylactic or other allergic reactions to influenza vaccine or any vaccine component or excipient (e.g. gentamicin or thimerosal) Acute infectious with fever > 38 degree Celsius and noninfectious diseases (within 72 hours) preceding enrollment in the trial The participants who have been taking immunoglobulin products or have had a blood transfusion during past 3 months before the beginning of the experiment Participation in other research study Pregnancy or plan to become pregnant for 60 days after enrollment or breast feeding Current alcohol abuse or drug addiction that might interfere with the ability to comply with trial procedures Any condition that in the opinion of the investigator would pose a health risk to the subject if enrolled, or could interfere with the evaluation of the vaccine Employee of any person employed by the Sponsor, the contract research organization (CRO), the PI, study site personnel, or site. Any test for HIV, HBsAg, Hep C antibody shows positive results with clinically significance