T-cell And General Immune Response to Seasonal Influenza Vaccine (SLVP018) Year 3, 2011

Inclusion Criteria:

   1. Otherwise healthy, ambulatory adults, ages 18-30 years (identical or fraternal twin
   pairs), 40-64 years (identical or fraternal twin pairs) or 65-100 years (identical
   twin pairs).

   2. Willing to complete the informed consent process.

   3. Availability for follow-up for the planned duration of the study at least 28 days
   after immunization.

   4. Acceptable medical history and vital signs.

Exclusion Criteria:

   1. Prior off-study vaccination with trivalent inactivated influenza vaccine (TIV) or live
   attenuated influenza vaccine (LAIV) in Fall 2011

   2. Allergy to egg or egg products, or to vaccine components, including thimerosal (if TIV
   multidose vials used)

   3. Allergy to latex (for Group F only - may be assigned to Fluzone High-Dose). Review
   with investigator.

   4. Life-threatening reactions to previous influenza vaccinations

   5. Active systemic or serious concurrent illness, including febrile illness on the day of
   vaccination

   6. History of immunodeficiency (including HIV infection)

   7. Known or suspected impairment of immunologic function, including, but not limited to,
   clinically significant liver disease, diabetes mellitus treated with insulin, moderate
   to severe renal disease or any other chronic disorder which, in the opinion of the
   investigator, might jeopardize volunteer safety or compliance with the protocol.

   8. Blood pressure >150 systolic or > 95 diastolic at Visit 1

   9. Hospitalization in the past year for congestive heart failure or emphysema.

10. Chronic Hepatitis B or C

11. Recent or current use of immunosuppressive medication, including glucocorticoids
   (corticosteroid nasal sprays, topical steroids and inhaled steroids are permissible).
   Use of oral steroids (<20mg prednisone-equivalent/day) may be acceptable after review
   by the investigator.

12. Malignancy, other than squamous cell or basal cell skin cancer (includes solid tumors
   such as breast cancer or prostate cancer with recurrence in the past year, and any
   hematologic cancer such as leukemia).

13. Autoimmune disease (including rheumatoid arthritis treated with immunosuppressive
   medication such as Plaquenil, methotrexate, prednisone, Enbrel) which, in the opinion
   of the investigator, might jeopardize volunteer safety or compliance with the
   protocol.

14. History of blood dyscrasias, renal disease, or hemoglobinopathies requiring regular
   medical follow up or hospitalization during the preceding year

15. Use of any anti-coagulation medication such as Coumadin or Lovenox, or anti-platelet
   agents such as aspirin (except aspirin up to 325 mg.day), Plavix, or Aggrenox must be
   reviewed by investigator to determine if this would affect the volunteer's safety.

16. Receipt of blood or blood products within the past 6 months

17. Medical or psychiatric condition or occupational responsibilities that preclude
   participant compliance with the protocol

18. Inactivated vaccine 14 days prior to vaccination

19. Live, attenuated vaccine within 60 days of vaccination

20. History of Guillain-Barre Syndrome

21. Pregnant or lactating woman

22. Use of investigational agents within 30 days prior to enrollment

23. Donation of the equivalent of a unit of blood within 6 weeks prior to enrollment

24. Any condition which, in the opinion of the investigator, might interfere with
   volunteer safety, study objectives or the ability of the participant to understand or
   comply with the study protocol.