What HIV vaccinations are available?

Updated: Jul 01, 2019
  • Author: Nicholas John Bennett, MBBCh, PhD, MA(Cantab), FAAP; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Vaccination efforts

The initial hope of an effective vaccine against HIV has not been fulfilled. Aside from the virus being able to rapidly mutate antigenic portions of key surface proteins, HIV infection progresses despite the host’s humoral and cellular immune responses; therefore, any vaccination effect needs to surpass the normal host response to HIV.

A study from Thailand suggests a possible benefit of vaccines in heterosexuals at risk for HIV-1 transmission. [145] In the randomized, multicenter, double-blind, placebo-controlled trial by Rerks-Ngarm et al, 16,402 healthy participants aged 18-30 years received either 4 priming injections of recombinant canarypox vector vaccine (ALVAC-HIV [vCP1521]) plus 2 booster shots of recombinant glycoprotein 120 subunit vaccine (AIDSVAX B/E) or placebo.

In the per-protocol analysis, which excluded subjects who seroconverted during the vaccination series, the vaccine efficacy was 26.2%. In the modified-intention-to-treat analysis, which excluded subjects who had baseline HIV-1 infection, the vaccine efficacy was 31.2%. However, the 95% confidence intervals in these analyses were extremely wide (-13.3 to 51.9 and 1.1 to 52.1, respectively), which precludes concluding that the vaccine had proven efficacy. [145]

Among study subjects who developed HIV-1 infection, viremia and CD4+ T cell counts were unchanged by vaccination. This suggests that, if infection did occur, there was no apparent immunologic benefit from having received the vaccine.

With respect to risk behavior, a post-hoc analysis of efficacy found that the combination of the HIV vaccines, ALVAC-HIV (vCP1521) and AIDSVAX B/E, was more effective in those who maintained lower-risk sexual behavior compared to those that reported high or increasing-risk behavior. [146]


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