This protocol is to compare the immune response of different influenza vaccines given by two different routes of administration in healthy adults ages 18 to 64 years.

This is a multi-center, randomized, partially blinded trial to compare the safety and immunogenicity of intramuscularly versus intradermally administered influenza vaccine in healthy 18-64 year old adults. Subjects will have blood drawn immediately prior to and approximately three to four weeks after vaccination. After the completion of the trial, all subjects will be offered influenza vaccine of the 2005-2006 formulation.

Inclusion Criteria:

1. Subject is healthy, as determined by medical history
2. Over 18 years of age and not yet 65 years old
3. Provides written informed consent
4. Able to attend all scheduled visits and to comply with all trial procedures
5. Women may be menopausal of 1 year or more or sugically sterile. Women of child-bearing potential must agree to be abstinent or to use a licensed form of barrier or hormonal contraception for the entire study period, and have a negative pregnancy test within 24 hours prior to vaccination.

Exclusion Criteria:

1. Breast-feeding
2. Receipt of an investigational drug, biologic or device in the 4 weeks preceding the trial vaccination
3. Planned participation in another clinical trial during the present trial period
4. History of Guillain-Barré Syndrome
5. Congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroid therapy
6. Hypersensitivity to any of the vaccine components (including eggs or egg products or thimerosol and gelatin) or history of a life-threatening reaction to the trial vaccine or a vaccine containing the same substances
7. Chronic illness that could interfere with trial conduct or completion
8. Blood or blood-derived products received in the past 3 months
9. Has received any inactivated vaccine within 2 weeks or live vaccine within 4 weeks prior to enrollment into this study
10. Vaccination planned within the 4 weeks following the trial vaccination
11. Known current HIV, hepatitis B (HBsAg) or hepatitis C infection or seropositivity
12. Prior vaccination against influenza within the past 6 months
13. Allergy shot in the 7-day period prior to enrollment and must not be scheduled to receive any allergy shots in the 7-day period after enrollment
14. On coumadin or heparin therapy or has known thrombocytopenia or bleeding disorder contraindicating vaccination
15. Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent
16. Febrile illness temperature >= 37.5°C on Day 0, prior to enrollment and vaccination
17. Any condition, that, in the opinion of the investigator, would pose a health risk to the participant
18. History of alcohol or drug abuse in the last 5 years
19. Planned travel outside the US between vaccination and the second study visit
20. Presence of any active skin disease at the injection site that, in the opinion of the Investigator, would impact vaccine delivery or assessment of vaccination site