T-cell And General Immune Response to Seasonal Influenza Vaccine (SLVP018) - Year 1, 2009

Inclusion Criteria:

   1. Otherwise healthy, ambulatory children or adults, ages 8-17 years (identical twin
   pairs), 18-30 years (identical or fraternal twin pairs), 40-49 years (identical or
   fraternal twin pairs) or 70-100 years (twin or non-twin adults).

   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.

   5. Negative urine pregnancy test for women of childbearing potential

   6. If the subject is female and of childbearing potential, she must use an acceptable
   method of contraception and not become pregnant for the duration of the study.
   (Acceptable contraception includes implants, injectables, combined oral
   contraceptives, effective intrauterine devices (IUDs), sexual abstinence, or a
   vasectomized partner).

Exclusion Criteria:

   1. Prior vaccination with TIV or LAIV in Fall 2009

   2. Allergy to egg or egg products, or to vaccine components, including gentamicin,
   gelatin, arginine or MSG (for LAIV only), or thimerosal (TIV multidose vials only).

   3. Life-threatening reactions to previous influenza vaccinations

   4. Asthma (LAIV groups only)

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

   6. History of immune deficiency

   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, blood pressure >150/95 at screening, or any other chronic
   disorder which, in the opinion of the investigator, might jeopardize volunteer safety
   or compliance with the protocol.

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

   9. Chronic Hepatitis B or C

10. Recent or current use of immunosuppressive medication, including glucocorticoids
   (corticosteroid nasal sprays are permissible).

11. Subjects in close contact with anyone who has a severely weakened immune system should
   not receive LAIV.

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, Plavix, Aggrenox may be acceptable after review by
   investigator.

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

17. Medical or psychiatric condition or occupational responsibilities that preclude
   subject 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.