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Overview of HIV Prevention

Joseph J. Eron, Jr., MD
Program Director
Daniel R. Kuritzkes, MD
Program Director
Sharon L. Hillier, PhD
Released: September 17, 2020
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Introduction

Recent reports from the Joint United Nations Program on AIDS[1] and the CDC[2] indicate that, globally, the number of people with new HIV infections is declining, due to the expansion of HIV programs and the emergence of new strategies to prevent HIV transmission, although declines have slowed in recent years. These successes are tempered by the continued increasing incidence of HIV in certain countries and in certain populations in the United States.[2] The UNAIDS report has suggested that reducing the number of new HIV infections to zero will require a combination of prevention strategies including behavior change, condom provision, male circumcision, focused programs for at-risk individuals, and access to ART and pre-exposure prophylaxis (PrEP).

HIV prevention trials have been conducted assessing a range of different approaches to decrease the risk of HIV infection, including behavioral interventions in men who have sex with men (MSM), vaccination, treatment of sexually transmitted diseases (STDs), circumcision, use of cervical diaphragms, early treatment of partners with HIV in serodiscordant relationships, the use of ARV agents in uninfected individuals to prevent infection, and several microbicides (Figure). Of these, male circumcision, a vaccine combination, tenofovir gel, oral emtricitabine/tenofovir disoproxil fumarate (DF), oral emtricitabine/tenofovir alafenamide (AF), and oral tenofovir DF have been shown to reduce HIV acquisition.[3-11] Early treatment of HIV has also been demonstrated to reduce the transmission of HIV to uninfected partners, demonstrating that effective treatment is a powerful tool for prevention of HIV.[12,13] Of note, other interventions, such as behavioral interventions, have been shown to reduce risk behaviors but have not been demonstrated to reduce HIV.[14]

Figure. The spectrum of HIV prevention strategies.

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Oral and topical ARVs have emerged as tools for the prevention of HIV acquisition and several completed studies have reported very promising results in heterosexual men and women and MSM.[7-11] However, the results of the studies have not been consistently positive, suggesting that interventions that may be highly effective for some communities may not be as acceptable or as well utilized in other communities. For example, the FEM-PrEP trial[15] of high-risk women and the VOICE trial[16] of women living in high seroincidence communities did not confirm the prophylactic benefit of oral and topical ARVs reported in other studies. However, results from a study of oral tenofovir DF (with the option of daily directly observed treatment) for prevention of HIV among people who inject drugs demonstrated that this strategy was effective in reducing the risk of infection.[17] At the same time, it is now well recognized that effective treatment of persons with HIV resulting in virologic suppression reduces HIV transmission, as demonstrated in both observational studies[18-21] and a randomized controlled trial in which provision of ARV treatment substantially reduced the risk of HIV acquisition by the HIV-uninfected partner.[12]

This module reviews the recent research on various HIV prevention strategies. Although some of these interventions have been shown to substantially reduce the incidence of HIV infection, it is increasingly being recognized that for HIV prevention to be successful, a range of different strategies are needed in order to have a set of prevention options available that can be implemented in high-risk communities and effectively meet the prevention needs of individual persons at risk.

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