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): 18.0-64.0,  Influenza Human immunodeficiency virus (HIV) infection defined as documented by an enzyme-linked immunosorbent assay (ELISA) and confirmed with a Western blot at any time prior to study entry. Serum HIV-1 antigen, plasma HIV-1 ribonucleic acid (RNA), or any Food and Drug Administration (FDA) approved antibody test by a method other than ELISA is acceptable as an alternative confirmatory test Males or non-pregnant females age 18-64, inclusive Women of child-bearing potential (not surgically sterile via tubal ligation, bilateral oophorectomy or hysterectomy or who are not postmenopausal for greater than or equal to 1 year) must agree to practice adequate contraception that may but is not limited to, abstinence, monogamous relationship with vasectomized partner, barrier methods such as condoms, diaphragms, spermicides, intrauterine devices, Depo-Provera injections or Implanon implants for at least 30 days following the last vaccination Are medically stable, as determined by the Investigator (based on review of health status, vital signs, medical history, and targeted physical examination. Vital signs must be within normal ranges prior to the first vaccination (heart rate 55-100, blood pressure systolic <160, blood pressure diastolic <90) Receipt of the 2009-2010 seasonal influenza vaccine at least two weeks prior to enrollment in this study Intend to be available for follow-up visits and phone call access through 7 months following receipt of H1N1 vaccine Are able to understand and comply with planned study procedures Subject receiving regular medical follow-up care for HIV Has a documented platelet count of >50,000mm^3 and an absolute neutrophil count (ANC) of >500mm^3 within the 3 months prior to study entry Provide written informed consent prior to initiation of any study procedures  Treatment for an opportunistic infection (OI) initiated within 2 weeks prior to enrollment, or have symptoms that have not stabilized Have a known allergy to eggs or other components of the vaccine (including polymyxin, neomycin, and chicken protein) Women who are pregnant or breastfeeding Have a positive urine or serum pregnancy test within 24 hours prior to vaccination Use of anticancer chemotherapy or radiation therapy (cytotoxic) within the preceding 36 months Have a neoplastic disease that will be treated with chemotherapy or radiation, or a history of any hematologic malignancy Have long term use of glucocorticoids including oral, parenteral or high-dose inhaled steroids. For oral or parenteral: prednisone or equivalent (greater than or equal to 2.0 mg/kg per day or greater than or equal to 20 mg total dose) for more than 2 consecutive weeks (or 2 weeks total) in the past 3 months. For inhaled steroids: >800 mcg/day of beclomethasone dipropionate or equivalent within the preceding 6 months. (Nasal and topical steroids are allowed.) Have an uncontrolled major psychiatric diagnosis Have a history of receiving immunoglobulin or other blood products within the 3 months prior to vaccination in this study Received an experimental agent (vaccine, drug, biologic, device, or medication) within 1 month prior to vaccination in this study or expect to receive an experimental agent during this study (prior to the Day 201 follow-up call)