The overall goal of this study is to study influenza vaccine responses in HIV infected individuals. Immunocompromised individuals require special protection from influenza, but may not respond appropriately to the standard killed vaccine. Patients who receive the H1N1 flu vaccine as part of their standard of care will be asked to donate blood samples for immunologic studies. These studies will determine whether participants were able to produce the appropriate antibodies to the vaccine and possibly identify predictors of vaccine responsiveness.

Our hypothesis is that vaccine responsiveness to the new H1N1 influenza vaccine will be compromised in HIV infected patients.

Inclusion Criteria:

1. A confirmed diagnosis of HIV-1 infection as documented by any licensed ELISA test kit and confirmed by Western blot at any time prior to study entry or any measurable HIV RNA viral load in the chart. Serum HIV-1 antigen, plasma HIV-1 RNA, or a second antibody test by a method other than ELISA is acceptable as an alternative confirmatory test.
2. > 18 years
3. Able to understand and comply with planned study procedures.
4. Provides written informed consent prior to initiation of any study procedures.
5. Subject should be 1) on stable antiretroviral therapy as outlined in the DHHS treatment guidelines for HIV-1 infected individuals OR 2) not on antiretroviral therapy and not intending to start treatment within the next 30 days.

Exclusion Criteria:

1. Has a known allergy to eggs or other components in the vaccines (these may include, but are not limited to: gelatin, formaldehyde, octoxinol and chicken protein).
2. Has a history, in the opinion of the site investigator, of severe reactions following previous immunization with seasonal TIV.
3. Participation in a novel H1N1 influenza vaccine study in the past two years.
4. Proven history, by RT-PCR, of novel influenza H1N1 infection, or, has a positive influenza diagnostic testing since June 2009 (specificity to H1N1 not required) prior to study entry.
5. Received any other live licensed vaccine within 4 weeks or inactivated licensed vaccine within 1 week prior to study entry.
6. Scheduled administration of any live virus vaccine or inactivated vaccine at or between entry and the Day 21 visit. NOTE: Live or inactivated vaccines expected to be administered between study entry and the Day 21 visit should be excluded to prevent potential interference with immunogenicity responses and confounding safety results. Regular seasonal flu vaccination will be allowed if is separated more than 7 days from the administration of the H1N1 vaccine.
7. Received a non-licensed agent (vaccine, drug, biologic, device, blood product, or medication) within 4 weeks prior to vaccination in this study
8. An acute illness and/or an oral temperature greater than or equal to 100.0 degrees F within 24 hours prior to study entry.
9. Use of anti-cancer chemotherapy or radiation therapy within the preceding 36 months of study enrollment, or has immunosuppression as a result of an underlying illness or treatment (other than HIV-1 infection).
10. Active neoplastic disease (excluding non-melanoma skin cancer, and HPV-related cervical dysplasia, CIN grades 1, 2 or 3).
11. Long term use of glucocorticoids, including oral or parenteral prednisone or equivalent (more than 2.0 mg/kg per day or more than 20 mg total dose) for more than 2 consecutive weeks (or 2 weeks total) in the past 3 months, or high-dose inhaled steroids (>800 mcg/day of beclomethasone dipropionate or equivalent) within the past 3 months (nasal and topical steroids are allowed).
12. Received immunoglobulin or other blood products
13. Current diagnosis of uncontrolled major psychiatric disorder.
14. History of Guillain-Barré Syndrome in the subject or subject's family (parents, siblings, half siblings, or children).
15. Any condition that would, in the opinion of the site investigator, place the subject at an unacceptable risk of injury or render the subject unable to meet the requirements of the protocol.

Duration of the study (21-28 days)

Serious adverse events include all Grade 3 or greater adverse events

Single Arm Study