Immunogenicity, Safety, and Tolerability of MF59-Adjuvanted Versus Non-Adjuvanted Influenza Vaccines in Patients With HIV-1 Infection

Inclusion Criteria: For HIV-1 Infected Subjects: * Adults between 18-60 years old (inclusive) * Any sex or ethnicity * Confirmed Diagnosis of HIV-1 infection * CD4+ cells count \>200 per mm3 within 3 months prior to inclusion in the study * HIV-1 viral load below 200 copies/mL within 90 days prior to inclusion in the study * Childbearing potential women must be willing to use an acceptable contraceptive method. Acceptable contraceptive methods are defined as one or more of the following: 1. Hormone contraceptive (such as oral, injectable, transdermal patch, subcutaneous implant, cervical ring) 2. Barrier (condom with spermicide or diaphragm with spermicide) at each intercourse and during the whole intercourse 3. Intra-uterine device (IUD) 4. Monogamous relation with vasectomized partner (must have been vasectomized at least six months before the volunteer entered the study) * No changes in the antiviral therapy (including HAART) for the previous 4 weeks and/or change in the predicted antiviral therapy through study Day 43 (3 weeks after the second dose of the vaccine) * No use of immunomodulatory therapy, including cyclosporine, interleukins, interferons, or systemic glucocorticoids (including inhalatory) within 3 months before study inclusion * Subjects capable of respecting all the study procedures and available for all visits scheduled to the investigation site * Subjects capable of understanding the nature and risk of the study proposed and signing the consent form * The subjects may have other underlying diseases, such as, but not limited to, hypertension, diabetes, cardiac ischemic disease, or hypothyroidism, however their symptoms/signs must be currently under control with medical treatment according to the investigator's evaluation For Healthy Adults: * Adults between 18-60 years old (inclusive) * Any sex and ethnicity * Subjects with good health as determined by medical history, physical evaluation, and investigator's clinical opinion * Childbearing potential women must be willing to use an acceptable contraceptive method. Acceptable contraceptive methods are defined as one or more of the following: 1. Hormone contraceptive (such as oral, injectable, transdermal patch, subcutaneous implant, cervical ring). 2. Barrier (condom with spermicide or diaphragm with spermicide) at each intercourse and during the whole sexual intercourse 3. Intra-uterine device (IUD) 4. Monogamous relation with vasectomized partner (must have been vasectomized for at least six months before the volunteer entered the study) * Subjects capable of respecting all the study procedures and available for all the visits scheduled at the investigation site * Subjects capable of understanding the nature and risk of the study proposed and signing the consent form There will be NO blood sample collection of healthy volunteers viewing the determination of their serological status regarding the HIV virus. Exclusion Criteria: For HIV-1-Infected Subjects: * HIV-1 viral load above 500 copies/mL within 6 months prior to inclusion in the study * Previous laboratory confirmed diagnosis of an infection by the novel H1N1 virus * Receipt of another vaccine against the novel H1N1 virus within 3 months prior to inclusion in the study * Any recent vaccine given within the last 21 days (inclusive) * History of allergic reaction to an influenza vaccine in the past, or a current or previous occurrence of allergy to egg or egg protein, kanamycin, and neomycin sulfate * Acute febrile disease (vaccination may be delayed up to 3 days after the resolution of the symptoms) * History of cancer, except for skin cancer, including Kaposi's Sarcoma, basal cell carcinoma, and non-invasive malignancy related to HPV * History of cognitive disorders * History of progressive or severe neurological disorders, including Guillain-Barré Syndrome * Pregnancy or breast-feeding * Use of immunomodulatory therapy, including cyclosporin, interleukins, and interferons, within 3 months prior to inclusion in the study * Receipt of parenteral immunoglobulin, hemotherapy, and/or plasma derivatives within 3 months prior to inclusion in the study * Projected life expectancy lower than 12 months * Receipt of any investigational product within 12 months prior to inclusion in the study For Healthy Adults: * Previous laboratory confirmed diagnosis of an infection by the novel H1N1 virus * Receipt of another vaccine against the novel H1N1 virus within 3 months prior to inclusion in the study * Any recent vaccine given within the last 21 days (inclusive) * History of allergic reaction to influenza vaccine in the past, or a current or previous allergy to egg or egg protein, kanamycin, and neomycin sulfate * Acute febrile disease (the vaccination may be delayed up to 3 days after symptoms resolution) * Pregnancy or breast-feeding * Receipt of parenteral immunoglobulin, hemotherapy, and/or plasma derivatives within 3 months prior to inclusion in the study * Receipt of any investigational product within 12 months prior to inclusion in the study