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.