T-cell And General Immune Response to Seasonal Influenza Vaccine (SLVP018) Year 2, 2010

Inclusion Criteria:

   1. Otherwise healthy, ambulatory children or adults, ages 8-17 years (identical twins),
   18-30 years (identical or fraternal twins), 40-59 years (identical or fraternal twins)
   or 70-100 years (identical twins).

   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. All female of childbearing potential, must use an acceptable method of contraception
   and not become pregnant for the duration of the study (approximately 1 month or to
   completion of Visit 3). (Acceptable contraception includes implants, injectables,
   combined oral contraceptives, effective intrauterine devices (IUDs), sexual
   abstinence, or a vasectomized partner).

Exclusion Criteria:

   1. Prior off-study vaccination with trivalent inactivated influenza vaccine (TIV) or live
   attenuated influenza vaccine (LAIV) in Fall 2010

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

   3. Life-threatening reactions to previous influenza vaccinations

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

   5. History of immunodeficiency

   6. 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.

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

   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 and inhaled steroids are permissible). Use of oral
   steroids (<20mg prednisone-equivalent/day) may be acceptable after review by the
   investigator.

11. 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).

12. 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.

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

14. Use of any anti-coagulation medication such as Coumadin or Lovenox, or anti-platelet
   agents such as aspirin, Plavix, Aggrenox must be reviewed by investigator to determine
   if this would affect the volunteer's safety.

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

16. Medical or psychiatric condition or occupational responsibilities that preclude
   subject compliance with the protocol

17. Inactivated vaccine 14 days prior to vaccination

18. Live, attenuated vaccine within 60 days of vaccination

19. History of Guillain-Barre Syndrome

20. Pregnant or lactating woman

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

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

23. 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.