Patient description: A 42-year-old healthy woman came to the clinic to have her flu shot in early October. She works in a rehab center and has no underlying disease. It's her first time getting the vaccine this year. She is married for 5 years and uses barrier methods of contraception. Her menstrual cycle is irregular. She does not smoke. She is not on any medications. She exercises regularly for 30 minutes a day at least 5 days a week. She has no history of allergies to any food or drugs. Her past surgical history is significant for tonsillectomy and she is otherwise healthy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-40.0,  Influenza Male or non-pregnant female (as indicated by a negative urine pregnancy test immediately prior to vaccine administration) between the ages of 18 and 40 years, inclusive Women of childbearing potential (not surgically sterile or postmenopausal for greater than or equal to 1 year) who are at risk of becoming pregnant must agree to practice adequate contraception (i.e., barrier method, abstinence, intrauterine devices, and licensed hormonal methods) for the entire study period Is in good health, as determined by vital signs (heart rate < 100 beats per minute, blood pressure: systolic less than or equal to 140 mm Hg and greater than or equal to 90 mm Hg, diastolic less than or equal to 90 mm Hg; oral temperature < 100 degrees Fahrenheit), medical history to ensure stable* medical condition and a targeted physical examination based on medical history. (*A stable medical condition is defined as no recent change in prescription medication, dose, or frequency of medication in the last 3 months and health outcomes of the specific disease are considered to be within acceptable limits in the last 6 months. Any change that is due to change of health care provider, insurance company, etc, or is done for financial reasons, as long as in the same class of medication, will not be considered a violation of the criterion. Any change to prescription medication due to improvement of a disease outcome will not be considered a violation of the criterion.) Able to understand and comply with planned study procedures Provide informed consent prior to initiation of any study procedures and are available for all study visits  Have a known allergy to eggs or other components of the vaccine (including gelatin, formaldehyde, octoxinol, aluminum hydroxide, and chicken protein) Have a positive urine or serum pregnancy test prior to vaccination (if female of childbearing potential) or women who are breastfeeding Have immunosuppression as a result of an underlying illness or treatment with immunosuppressive or cytotoxic drugs, or use of anticancer chemotherapy or radiation therapy within the preceding 36 months Have an active neoplastic disease or a history of any hematologic malignancy Have long-term use of oral steroids, parenteral steroids, or high-dose inhaled steroids (>800 micrograms/day of beclomethasone dipropionate or equivalent) within the preceding 6 months (nasal and topical steroids are allowed.) Have a history of receiving immunoglobulin or other blood product within the 3 months prior to enrollment in this study Have received any other licensed vaccines within 2 weeks (for inactivated vaccines) or 4 weeks (for live vaccines) prior to vaccination in this study Have an acute or chronic medical condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the evaluation of responses. (This includes, but is not limited to: known chronic liver disease, significant renal disease, unstable or progressive neurological disorders, diabetes mellitus, and transplant recipients) Have a history of severe reactions following immunization with contemporary influenza virus vaccines Have an acute illness, including an oral temperature greater than 100.4 degrees Fahrenheit, within 1 week of vaccination