Based on the scientific evidence, several questions remain, say Drs. Johnston and Fauci: Can a vaccine that does not prevent HIV infection but reduces virus levels and preserves a segment of uninfected CD4+ T cells from destruction benefit the immunized individual" Might people immunized with T-cell vaccines before HIV exposure remain disease-free for a prolonged period once they are infected"
Additionally, T-cell vaccines may reduce secondary HIV transmission if they can help the immune system keep viral replication at a very low level for a long time. Studies have suggested that people with high levels of virus--namely those in the early and late stages of infection--are most likely to infect their sexual partners. A preventive vaccine given before exposure to HIV might stifle the initial burst of virus, better control virus levels and potentially reduce that person’s ability to infect other people, Drs. Johnston and Fauci assert.
Vaccines of this type present several complications, however. T-cell-mediated control of HIV infection may not stave off disease forever. Additional human studies would be needed to determine if the vaccine also reduces the spread of HIV. Finally, an HIV vaccine that delays but does not completely preve
Source:NIH/National Institute of Allergy and Infectious Diseases