• Number of Participants in the CD4 Less Than 200/mL Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 10 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 10 days after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 10 post first H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 10 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 21 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 21 days after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 21 post first H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 21 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 10 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 10 days after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 10 post second H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 10 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 21 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 21 days after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 21 post second H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 21 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 180 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 180 days after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 180 post second H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 180 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 10 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 10 days after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 10 post first H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 10 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 CD4 200/mL or Greater Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 21 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 21 days after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 21 post first H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 21 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 10 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 10 days after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 10 post second H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 10 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 21 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 21 days after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 21 post second H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 21 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With 4-Fold or Greater Hemagglutination Inhibition Assay (HAI) Antibody Titer Increases Against the Influenza H1N1 2009 Virus 180 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 180 days after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from participants for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. A participant met the threshold of a 4-fold rise in titer if the Day 0 titer was less than 1:10 (the assay's lowest level of detection) and the Day 180 post second H1N1 vaccination titer was 1:40 or greater, or the Day 0 titer was greater than or equal to 1:10 and the Day 180 titer was an increase by 4-fold or more.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus at Baseline and 10 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to vaccination and 10 days after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants at Day 0 prior to vaccination and 10 days after the first vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 21 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 21 after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 21 days after the first vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 10 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 10 after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 10 days after the second vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 21 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 21 after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 21 days after the second vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 Less Than 200/mL Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 180 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 180 after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 180 days after the second vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus at Baseline Prior to the First Dose of H1N1 Vaccine [ Time Frame: Day 0 prior to the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants at Day 0 prior to the first vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 10 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 10 after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 10 days after the first vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 21 Days Following the First Dose of H1N1 Vaccine [ Time Frame: Day 21 after the first vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 21 days after the first vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 10 and 21 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 10 and Day 21 after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 10 and 21 days after the second vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants in the CD4 200/mL or Greater Stratum With a Serum Hemagglutination Inhibition Assay (HAI) Antibody Titer of 1:40 or Greater Against the H1N1 2009 Virus 180 Days Following the Second Dose of H1N1 Vaccine [ Time Frame: Day 180 after the second vaccination ] [ Designated as safety issue: No ]
  Blood was collected from all participants 180 days after the second vaccination for testing in the HAI assay with Influenza H1N1 2009 virus as the assay antigen. Each sample was tested at least twice according to standard operating procedures and the result of each replicate reported. A participant is counted if the geometric mean of the replicate values was 1:40 or greater.
  
  
• Number of Participants Reporting Solicited Subjective Systemic Reactions After the First Vaccination [ Time Frame: Within 8 days post first vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants maintained a memory aid to record daily the occurrence of systemic symptoms of feverishness, malaise, myalgia, headache, and nausea for 8 days (Day 0-7) after vaccination based on their interference with daily activities. Participants are counted if they reported experiencing the symptom at any severity on any of the 8 days.
  
  
• Number of Participants Reporting Solicited Subjective Systemic Reactions After the Second Vaccination [ Time Frame: Within 8 days post second vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants maintained a memory aid to record daily the occurrence of systemic symptoms of feverishness, malaise, myalgia, headache, and nausea for 8 days (Day 0-7) after vaccination based on their interference with daily activities. Participants are counted if they reported experiencing the symptom at any severity on any of the 8 days.
  
  
• Number of Participants Reporting Fever After the First Vaccination [ Time Frame: Within 8 days post first vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants were provided a thermometer and a memory aid to record daily oral temperatures for 8 days (Day 0-7) after vaccination. Participants are counted as experiencing fever if they reported oral temperatures of 38 degrees Celsius or higher on any of the 8 days.
  
  
• Number of Participants Reporting Fever After the Second Vaccination [ Time Frame: Within 8 days post second vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants were provided a thermometer and a memory aid to record daily oral temperatures for 8 days (Day 0-7) after vaccination. Participants are counted as experiencing fever if they reported oral temperatures of 38 degrees Celsius or higher on any of the 8 days.
  
  
• Number of Participants Reporting Solicited Subjective Local Reactions After the First Vaccination [ Time Frame: Within 8 days post first vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants maintained a memory aid to record daily the occurrence of local symptoms of pain, tenderness and swelling for 8 days (Day 0-7) after vaccination based on their interference with daily activities. Participants are counted if they reported experiencing the symptom at any severity on any of the 8 days.
  
  
• Number of Participants Reporting Solicited Subjective Local Reactions After the Second Vaccination [ Time Frame: Within 8 days post second vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants maintained a memory aid to record daily the occurrence of local symptoms of pain, tenderness and swelling for 8 days (Day 0-7) after vaccination based on their interference with daily activities. Participants are counted if they reported experiencing the symptom at any severity on any of the 8 days.
  
  
• Number of Participants Reporting Solicited Quantitative Local Reactions After the First Vaccination [ Time Frame: Within 8 days post first vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants maintained a memory aid to record daily the occurrence of local reactions of swelling and redness for 8 days (Day 0-7) after vaccination. If the reaction was present, the maximum diameter was measured in millimeters (mm). Participants are counted if they were reported as experiencing the reaction with any measurement greater than 0 mm on any of the 8 days.
  
  
• Number of Participants Reporting Solicited Quantitative Local Reactions After the Second Vaccination [ Time Frame: Within 8 days post second vaccination (Day 0-7). ] [ Designated as safety issue: Yes ]
  Participants maintained a memory aid to record daily the occurrence of local reactions of swelling and redness for 8 days (Day 0-7) after vaccination. If the reaction was present, the maximum diameter was measured in millimeters (mm). Participants are counted if they were reported as experiencing the reaction with any measurement greater than 0 mm on any of the 8 days.
  
  
• Number of Participants Reporting Vaccine-Associated Serious Adverse Events (SAEs) [ Time Frame: Day 0 through Day 180 after the last vaccination ] [ Designated as safety issue: Yes ]
  Serious adverse events included any untoward medical occurrence that resulted in death; was life threatening; was a persistent/significant disability/incapacity; required in-patient hospitalization or prolongation thereof; resulted in a congenital anomaly/birth defect; may have jeopardized the participant or required intervention to prevent one of these outcomes; or was described as Guillain-Barré Syndrome. Association to vaccination was determined by a study clinician licensed to make medical diagnosis.
  
  

Recently, a novel swine-origin influenza A/H1N1 virus was identified as a significant cause of febrile respiratory illnesses in Mexico and the United States. It rapidly spread to many countries around the world, prompting the World Health Organization (WHO) to declare a pandemic on June 11, 2009. The immunosuppression associated with human immunodeficiency virus (HIV)-infection has been related to diminished immune responses to vaccination against multiple pathogens, including influenza. The widespread use of antiretroviral therapy has resulted in a significant decrease in the mortality from HIV/acquired immune deficiency syndrome (AIDS) and, as a result, HIV-infected subjects constitute a demographically growing subpopulation in the United States. Currently, novel H1N1 vaccines are being evaluated in the general population. Researchers propose to evaluate the safety and immunogenicity of the novel H1N1 vaccines in HIV-infected subjects, because the data from clinical trials enrolling healthy subjects may not apply to immunosuppressed individuals; and an evaluation of the immune responses to vaccination against new, pandemic influenza viruses has never been performed in HIV-infected subjects. This is a randomized, open label, Phase II study in HIV seropositive males and non-pregnant females, aged 18-64 years. This study is designed to investigate the safety, reactogenicity, and immunogenicity of an inactivated influenza H1N1 virus vaccine at 2 dose levels. Subjects will be randomized into 2 dose groups, stratified by cluster of differentiation (CD4) cell count at enrollment (120 subjects per dose group with 60 subjects per CD4 cell count stratum, <200/mL or greater than or equal to 200/mL) to receive intramuscular (IM) inactivated influenza H1N1 vaccine at 15 mcg (Group 1) or 30 mcg (Group 2). The H1N1 vaccine will be administered at Day 0 and Day 21. Following immunization, safety will be measured by assessment of adverse events through 21 days following the last vaccination (Day 42 for those receiving both doses and Day 21 for those who do not receive the second dose), serious adverse events and new-onset chronic medical conditions through 7 months post first vaccination (Day 201), and reactogenicity to the vaccine for 8 days following each vaccination (Day 0-7). A CD4/CD8 panel and viral load will be measured prior to first vaccination on Day 0 and at Day 10 post the second vaccination. Immunogenicity testing will include hemagglutination inhibition assay (HAI) and neutralizing antibody testing on serum obtained on the day of each vaccination (prior to vaccination), on Day 10 after each vaccination, 21 days following the second vaccination (Day 42) and 6 months after the second vaccination (Day 201). The primary objectives of this study are: (safety), to assess the safety of the unadjuvanted, inactivated H1N1 vaccine in HIV-1 seropositive adults when administered at the 15 mcg or 30 mcg dose and (immunogenicity) to assess the antibody response following 1 and 2 doses of inactivated H1N1 vaccine administered intramuscularly at the 15 mcg or 30 mcg dose levels in HIV-1 seropositive adults stratified by CD4 count at enrollment.