Tracking Mosaico, mRNA, and Broadly Neutralizing Antibody Vaccines
Updated July 2026. After 40+ years of research and over $100 billion invested, an effective HIV vaccine remains elusive. HIV's rapid mutation rate, integration into host DNA, and ability to establish latent reservoirs present unique challenges. As of 2026, no HIV vaccine candidate is in active Phase 3 development. All prior Phase 3 efficacy trials — RV144, HVTN 702 (Uhambo), HVTN 705/706 "Imbokodo" and Mosaico, and PrEPVacc — either failed to meet endpoints or were discontinued at interim analysis. Current efforts have shifted to earlier-phase work: mRNA HIV vaccines (Moderna/IAVI, applying COVID-19 vaccine technology; noted early safety signals include skin reactions in some trials), germline-targeting immunogens designed to prime rare B cell precursors of broadly neutralizing antibodies (bNAbs), and therapeutic vaccines aimed at HIV remission. A new Phase 1 trial, IAVI G004, is planned to launch in 2026 to test a booster designed to further strengthen antibody responses toward broadly protective bNAbs.
Developer: Janssen Pharmaceuticals (Johnson & Johnson) / HVTN
Platform: Mosaic adenovirus 26 (Ad26) vector prime + clade C gp140 protein boost
Target Population: Men who have sex with men and transgender individuals in Europe and Americas
Design: Tetravalent mosaic immunogens designed to induce broad immune responses against diverse HIV-1 strains
Trial Enrollment: Phase 2b/3 trial (HVTN 706) launched 2019, enrolling 3,800 participants across 8 countries (USA, Brazil, Argentina, Italy, Poland, Spain, Peru, Mexico).
Outcome: On January 18, 2023, Janssen and HVTN announced that the Mosaico trial was discontinued after a scheduled interim analysis by the independent Data and Safety Monitoring Board found that the regimen was not effective in preventing HIV infection compared with placebo. No safety issues were identified.
Background: Follows the earlier discontinuation of the Ad26.Mos4.HIV-based Imbokodo (HVTN 705) trial in women in sub-Saharan Africa (2021), which also failed to meet its efficacy endpoint. Together, these results ended the Janssen mosaic Ad26 HIV vaccine program.
Developer: Imperial College London / MRC Clinical Trials Unit / African partners
Platform: DNA prime + MVA (modified vaccinia Ankara) boost encoding CN54 HIV-1 immunogens
Innovation: First trial combining PrEP (pre-exposure prophylaxis) with a vaccine
Trial: Phase 2b/3 trial in Uganda, Tanzania, Mozambique, and South Africa, enrolling 1,668 participants. Comparing vaccine regimens alone, PrEP alone, and combination.
Outcome: In December 2023, the independent Data Monitoring Committee recommended stopping further vaccinations after an interim analysis concluded that the vaccine regimens were unlikely to demonstrate efficacy against HIV infection. Follow-up of participants for PrEP-related endpoints continued.
Rationale: The trial was designed to test whether combining vaccine and PrEP might provide better protection than either alone, potentially reducing PrEP pill burden — a rationale that remains attractive but awaits new candidates.
Developer: Moderna / IAVI (International AIDS Vaccine Initiative)
Platform: mRNA platform encoding HIV envelope proteins
Goal: Prime B cells to generate broadly neutralizing antibodies (bNAbs) targeting conserved HIV epitopes
Innovation: Uses "germline targeting" approach to guide immune system toward producing rare bNAbs that can neutralize diverse HIV strains
Status: Phase 1 trial (IAVI G002) completed 2023, showed successful B cell priming in 97% of participants. Phase 2 trials expanding. Building on success of mRNA COVID-19 vaccine platform.
Developer: Vir Biotechnology
Platform: Long-acting broadly neutralizing antibody (bNAb)
Mechanism: Monoclonal antibody targeting HIV envelope protein, preventing viral entry
Goal: Provide passive immunity with 6-12 month protection from single injection
Status: Phase 2 trials evaluating safety, pharmacokinetics, and efficacy. Could complement or substitute for daily PrEP pills.
Developer: Scripps Research / IAVI
Platform: Protein nanoparticle designed to activate rare B cell precursors
Innovation: "Germline targeting" - trains immune system through sequential immunizations to produce bNAbs
Status: Phase 1 trial showed 97% of participants developed targeted B cells. Advancing to Phase 2 with booster components.
Goal: Induce HIV remission in infected individuals (functional cure)
Approaches:
Status: Multiple Phase 1/2 trials ongoing. Some show enhanced immune control of HIV replication off antiretroviral therapy, but sustained remission remains rare.
Developer: Janssen / HVTN
Status: Follow-up to HVTN 705 "Imbokodo" trial (discontinued 2021)
Platform: Similar Ad26 mosaic approach with modifications
Note: Learning from previous trial to optimize immunogen design and dosing schedules.
Developer: Duke University / NIAID
Platform: Consensus HIV envelope trimer protein
Goal: Induce broadly neutralizing antibodies through stabilized envelope protein presentation
Status: Phase 1 safety and immunogenicity trials ongoing.
HIV vaccine development faces unprecedented challenges: extreme viral diversity (>70 million variants per person), rapid mutation (>10,000x faster than influenza), integration into host DNA creating latent reservoirs, and destruction of CD4+ T cells (the cells that coordinate immune responses). The virus also uses glycan shields to hide conserved epitopes from antibodies. No previous HIV vaccine trial has shown >50% efficacy. However, advances in structural biology, computational design, and mRNA technology provide new tools. The path forward likely involves combinations of approaches: bNAbs for passive protection, germline-targeting vaccines for active immunity, and therapeutic vaccines to achieve functional cure.