Can a vaccine boost HIV immunity in people already on treatment?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Ability and willingness to provide informed consent. * Age ≥18 years at time of consent * People with HIV (PWH) with confirmed HIV-1 infection as documented by medical records and enrolled in the SHCS. * SHCS participants with known bnAb inducer- and non-neutralizing Ab inducer (nnAb inducer) status. (Note: Information on bnAb/nnAb status is available through SHCS-linked research prior to recruitment and has been obtained from analysis of SHCS biobanked plasma samples from off-ART and/or on-ART timepoints. Based on this information participant will be classified into bnAb inducers and nnAb inducers.) * On suppressive ART with plasma HIV-1 RNA \<50 copies/ml for at least 1 year prior to screening. \[Note: Intermittent blips (HIV-1 RNA between 50-200 copies) documented in prior years on ART are allowed but viral load at screening must be \<50 copies. No switch to a novel ART regimen allowed 1 month before IMP administration. Switching from TDF to TAF and vice versa is not considered as switch to a novel regimen.\] * CD4+ cell count \> 250 cells/mm3 or CD4+ cell % ≥ 15% at screening (- 90 days prior to IMP administration) * At screening: Absolute neutrophil count (ANC) ≥ 750/mm3 * At screening: Platelets ≥ 100,000/mm3 * At screening: Alanine aminotransferase (ALT) \< 2.5 x upper limit of normal (ULN) based on the institutional normal range * At screening: Haemoglobin (Hgb): * ≥ 10.0 g/dL for volunteers who were assigned female sex at birth (AFAB) * ≥ 11.0 g/dL for cisgender volunteers who were assigned male sex at birth (AMAB) and for transgender men who have been on hormone therapy for more than 6 consecutive months * ≥ 11.0 g/dL for transgender women who have been on hormone therapy for more than 6 consecutive months * For transgender volunteers who have been on hormone therapy for less than 6 consecutive months, determine Hgb eligibility based on their sex assigned at birth. Persons of pregnancy potential * Must have a negative beta human chorionic gonadotropin (β-HCG) pregnancy test (urine or serum) on day 0 before IMP administration. * All participants born female who are engaging in sexual activity that could lead to pregnancy must commit to use of an effective method of contraception from 21 days before IMP administration to week 24 of the study. * Effective contraception includes condoms (male or female) with or without spermicide, diaphragm or cervical cap with spermicide, intrauterine device, hormonal contraception, including contraceptive implant or injectable, oral contraception, successful vasectomy in the male partner. * Participants born female do not have to use birth control if they are not engaging in sexual activity that could lead to pregnancy or are not of reproductive potential such as having undergone hysterectomy, bilateral oophorectomy, or tubal ligation, postmenopausal (amenorrhea for at least 1 year), surgically sterile. Exclusion Criteria: * • Presence of other, HIV-unrelated, immunosuppression considered as relevant by the site investigator (e.g. a daily steroid intake of ≥20mg for 3 months is considered clinically relevant) * Ongoing signs and symptoms of a febrile illness at the time of the vaccination (temperature \> 37.5°, and e.g. flu-like or other symptoms of a febrile illness) * Reduced health status due to other illnesses, which would not allow to participate in this study. * Volunteer who is pregnant or breast-feeding * Previous receipt of any anti-HIV monoclonal antibody or HIV vaccine. * Receipt of a non-HIV experimental vaccine(s) received within the last 6 months before IMP administration. Exceptions include vaccines that have subsequently undergone licensure or Emergency Use Authorization (EUA) by the FDA, World Health Organization (WHO) emergency use listing (EUL), Swissmedic licensure, European Medicines Agency (EMA) licensure. * Receipt of any other vaccine within 28 days prior to IMP administration (d0) * Is currently participating in or has participated in a clinical study with an investigational compound or device from in the last 45 days prior to Day 0 and throughout the study treatment period. * History of serious reaction (e.g., hypersensitivity, anaphylaxis) to any vaccine or component of the IMP * Asplenia or functional asplenia * Site investigator concern for difficulty with venous access based on clinical history and physical examination