Study of Seasonal Influenza Vaccine Against H5N1 Avian Influenza Virus

Inclusion Criteria: 1. Aged 18-49 years. 2. Healthy as determined by the PI or designate 3. Willing to give informed consent. 4. Willing to attend follow-up appointments and undergo study procedures. 5. US passport holder residing in Bangkok 6. If military, have a letter of approval for participation from the chain of command (Unit Commander). Exclusion Criteria: 1. History of hypersensitivity to eggs, egg proteins, gentamicin, gelatin or arginine. 2. Severe or life-threatening reaction to any previous vaccine. 3. History of chronic respiratory illness, including asthma and sinusitis. 4. History of heart disease 5. History of kidney disease 6. Metabolic disease such as diabetes 7. Immunocompromised as determined by the PI, or a household contact of an immunocompromised individual. 8. History of Guillain-Barre syndrome. 9. Blood disease including sickle cell disease and/or bleeding tendency (by history or based on medical records). 10. Any influenza vaccination within the previous 6 months, or any other vaccine within 30 days of either dose of influenza vaccine. 11. Pregnant woman or nursing mother or unwilling to use reliable contraception during the study period until the final day of follow-up. 12. Blood donation within the preceding 3 months, or screening hemoglobin value of \<12.5 g/dl. 13. Receipt of blood products including immunoglobulins within the preceding 3 months. 14. Receiving any of the following therapies: aspirin, warfarin, theophylline, phenytoin, aminopyrine, immunosuppressive drugs, 15. Receipt of any antiviral agents within 48 hours of vaccine administration. 16. HIV positive on screening blood tests. 17. Any other condition that in the opinion of the study investigator warrants exclusion from the study.