Systems Biology of Trivalent Influenza Vaccine (TIV) in Young and Elderly

Inclusion Criteria: 1. Healthy individuals aged 25-40 years, or ≥65 years old. 2. Able to understand and give informed consent. 3. Women of child-bearing potential (not surgically sterile via tubal ligation, bilateral oophorectomy or hysterectomy or who are not postmenopausal for ≥1 year) must agree to practice adequate contraception that may include, but is not limited to, abstinence, monogamous relationship with vasectomized partner, barrier methods such as condoms, diaphragms, spermicides, intrauterine devices, and licensed hormonal methods for 30 days before and 30 days after trivalent Influenza vaccination. Exclusion Criteria: 1. Receipt of immune products: * Receipt of blood products 3 months prior to study entry or expected receipt through 6 months after study entry * Receipt of any live virus vaccines within 4 weeks prior to study entry or expected receipt within 4 weeks after study entry\* * Receipt of any inactivated vaccine within 2 weeks or expected receipt within 2 weeks after study entry\* * Receipt of the 2010-2011 influenza vaccine 2. Documented influenza infection during the 2010-2011 influenza season. Not excluded from the study, volunteers with prior upper respiratory infections during the 2010-2011 influenza illness. 3. Presence of co-morbidities or immunosuppressive states such as: * Chronic medical problems including (but not limited to) insulin dependent diabetes, severe heart disease, severe lung disease, severe liver disease, severe kidney disease, auto immune diseases, severe gastrointestinal diseases, and uncontrolled hypertension. * Alcohol or drug abuse and psychiatric conditions that in the opinion of the investigator would preclude compliance with the trial or interpretation of safety or endpoint data. * Impaired immune function or chronic infections including (but not limited to) HIV, hepatitis B or C; organ transplant; cancer; current and/or expected receipt of chemotherapy, radiation therapy or any other cytotoxic or immunosuppressive therapy \[i.e. more than 10 mg of prednisone given daily or on alternative days for 2 weeks or more in the past 3 months\*; receipt of high-dose inhaled steroids is also an exclusion criteria (nasal and topical steroids are allowed.)\], congenital immunodeficiency, anatomical or functional asplenia. * Pregnancy or breast feeding 4. Conditions that could affect the safety of the volunteers such as: * Severe reactions to prior vaccination with TIV, including anaphylaxis. * History of Guillain Barré syndrome * History of bleeding disorders * Any allergy to any component of the vaccine including egg allergy. 5. Volunteers with any acute illness, including any fever (\> 100.4 F \[\> 38.0C\], regardless of the route) within 3 days prior to study entry \*. 6. Social, occupational, or any other condition that in the opinion of the investigator might interfere with compliance with the study and vaccine evaluation. * Note: An individual who initially is excluded from study participation based on one or more of the time-limited exclusion criteria (e.g., acute illness, receipt or expected receipt of live or inactivated vaccines ) may be reconsidered for enrollment once the condition has resolved as long as the subject continues to meet all other entry criteria. Subjects receiving \> 10 mg/day of prednisone or its equivalent daily or on alternate days for more than 2 weeks may enter the study after therapy has been discontinued for more than 3 months.