Evaluation of Priming Effects by PLAI Vaccine on the Subsequent Response to Inactivated H5N1 Vaccine

Inclusion Criteria: * Participated in the Phase II study Protocol No.: GPO AVIAN FLU Vaccine-V02-2 * Healthy * Age 18-49 years old * Having Thai ID card or equivalent * Anti HIV - Negative * 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) * Able to read and write and sign written informed consent. Exclusion Criteria: * Known history of egg allergy * Having had recently influenza infection confirmed as H5 * Receiving other vaccination against H5N1 * History of bronchial asthma * History of chronic lung diseases * History of chronic rhinitis * History of immunodeficiency state * History of immunosuppression\< 6 months prior to immunization * History of heavy smoking (more than 5 packs per day) * History of alcoholic (pure drink 200 ml per day) * Acute infectious and noninfectious diseases (within 2 weeks) * HIV positives * The volunteers who have been taking immunoglobulin products or have had a blood transfusion during past three months before the beginning of the experiment * Participation in other research study or stop participant less than 1 month * Pregnancy or plan to become pregnant for 60 days after enrollment or breast feeding * Poultry workers