Safety and Immunogenicity of a Tetravalent Dengue Vaccine in HIV-Positive Adults

The aim of the study was to evaluate the safety and immunogenicity of the Dengue vaccine in a population of special interest, such as HIV-positive adults previously exposed to dengue.

Primary Objective:

* To describe the safety of each injection of CYD dengue vaccine in HIV-positive adults previously exposed to dengue.

Secondary Objectives:

* To describe the humoral immune response to each dengue serotype at baseline and after each injection of CYD dengue vaccine in HIV-positive adults previously exposed to dengue.
* To detect the CYD dengue vaccinal viremia post-Inj 1 in HIV-positive adults previously exposed to dengue.
* To describe changes in CD4 count and HIV RNA viral load after each injection of CYD dengue vaccine in HIV-positive adults previously exposed to dengue.

Observational Objective:

* To describe the FV (YF, Dengue, Zika) serological status in the study population at baseline.

Eligible subjects were randomized in a 2:1 ratio into 1 of 2 groups to receive 3 injections of either CYD dengue vaccine or placebo at 0, 6, and 12 months. The enrollment of subjects was carried out in two steps, including an early safety data review before the second step. The duration of each subject's participation in the study was approximately 18 months.

Eligibility Criteria:
Inclusion Criteria:

* Aged 18 to 50 years on the day of first study vaccination (study product administration) ("18 to 50" means from the day of the 18th birthday to the day before the 51th birthday)
* Inform concent form has been signed and dated
* Able to attend all scheduled visits and to comply with all trial procedures
* Documented seropositivity for HIV-1 infection based on the Brazilian HIV Guidelines' laboratory criteria (i.e., two positive results obtained from different and independent determination methods) or detectable HIV-1 viral load results in the past
* Stable HIV condition according to Brazilian HIV Guidelines (i.e., with both CD4 count \> 350 cells/mm3 and sustainable and undetectable HIV viral load \[\< 50 copies/mL\]) for at least 1 year before consent
* Stable antiretroviral (ART) regimen based on local HIV protocol for at least 1 year before consent.
* Previous exposure to dengue confirmed by rapid diagnostic test (RDT) or dengue IgG ELISA

Exclusion Criteria:

* Subject is pregnant, or lactating, or of childbearing potential (to be considered of non-childbearing potential, a female must be pre-menarche or post-menopausal for at least 1 year, surgically sterile, or using an effective method of contraception or abstinence from at least 4 weeks prior to the first vaccination until at least 4 weeks after the last vaccination)
* Participation at the time of study enrollment (or in the 4 weeks preceding the first trial vaccination) or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure
* Receipt of any vaccine in the 4 weeks preceding the first trial vaccination or planned receipt of any vaccine in the 4 weeks following any trial vaccination
* Previous vaccination against dengue disease with either the trial vaccine or another vaccine
* Receipt of immune globulins, blood or blood-derived products in the past 3 months
* Self-reported or suspected congenital or acquired immunodeficiency, except HIV; or receipt of immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
* Previous acquired immunodeficiency syndrome (AIDS), defined as the occurrence of opportunistic infection in the last 2 years before consent
* Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccines used in the trial or to a vaccine containing any of the same substances
* Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
* Current alcohol abuse or drug addiction
* Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
* Moderate or severe acute illness/infection (according to investigator judgment) or febrile illness (temperature ≥ 38.0°C) on the day of vaccination. A prospective subject should not be included in the study until the condition has resolved or the febrile event has subsided
* Identified as an Investigator or employee of the Investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (i.e., parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study
* Previous CD4 count \< 200 cells/mm3 (nadir) since diagnosis of HIV
* History of chronic and active hepatitis B infection or HBsAg-positive
* History of chronic and active hepatitis C infection or HCV Ab-positive
* Aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine \> 3 times the upper limit of normal range (ULN)
* Hemoglobin (Hb) \< 10 g/dL
* White blood cell count (WBC) \< 1500 cells/mm3
* Platelets \< 100,000 cells/mm3.