The HIV epidemic in the U.S. is geographically localized and is further focused in specific populations, creating “hot spots” of transmission nested within sexual and/or drug use risk networks. Two populations at highest risk are men who have sex with men (MSM), particularly Black MSM, and women of Black and Hispanic race/ethnicity.[2
] HIV transmission also persists in White MSM and substance users. The advent of antiretroviral therapy (ART) and the plummeting of HIV-related death rates in the United States have led at-risk persons to view HIV prevention to be less urgent. [4
] Failure to lower HIV incidence in the U.S. during the potent antiretroviral therapy era likely reflects this “HIV complacency” alongside a systemic failure to effectively reach the persons at highest risk with risk reduction interventions and for those with recognized or unrecognized HIV infection with ART.
In 2008, the NIH-funded HIV Prevention Trials Network (HPTN) completed a systematic review of available literature and an analysis of available data on HIV prevalence and reported new HIV infections in the U.S .[5
] Based on this review, an HPTN Domestic Prevention Research Agenda was developed (http://www.hptn.org/web%20documents/DPWG/HPTNDomesticResearchAgenda03-29-08.pdf
, accessed September 28, 2009). In addition, based on results of the analysis of available data on reported new HIV infection in the U.S., it was apparent that approximately half of the newly reported cases were detected in MSM and that one quarter of cases were occurring in women of color. Thus, clearly these populations needed to be considered as special priorities for HIV prevention efforts because of their disproportionate disease burden. For example, Black MSM represent <1% of the U.S. population but 25% of the new HIV cases.[5
] HIV in U.S. women is distributed in highly skewed geographical venues. While Black and Hispanic women constitute 24% of all U.S. women, they accounted for 82% of HIV cases in women in 2005, based on data from 33 states with confidential name-based reporting.[6
] In addition, the heightened risk among women of color is dramatically demonstrated by the nearly 23-fold higher rate of AIDS diagnoses for Black women (45.5/100,000 women) and nearly 6-fold higher rate for Hispanic women (11.2/100,000) compared to the rate for white women (2.0/100,000).[6
HPTN are also exploring new research concepts for other key populations that have a heavy HIV burden in the U.S., such as non-minority MSM. For many at-risk persons, substance use and intercurrent mental health issues (e.g., depression) may play a major role in potentiating HIV spread. Future prevention clinical trials that address these primary drivers of risk-taking behavior and poor adherence could be helpful in enhancing HIV prevention.
As a most urgent priority, HPTN investigators have focused on Black MSM and women at risk as two relatively neglected populations at highest risk in the domestic U.S. HIV epidemic. Several questions were identified that required urgent attention prior to embarking on large HIV prevention effectiveness studies in these latter populations. These included: What are accurate estimates of HIV incidence in these populations? How can persons at risk who are least likely to be engaged in HIV prevention programs be reached? What are the types of prevention interventions that are likely to be feasible, acceptable, and effective in these individuals? How can individuals with unrecognized HIV be connected to HIV testing services? How can those with known HIV infection be linked and engaged in HIV care? How can those on ART achieve complete viral suppression? To begin to address these questions, several critical feasibility studies have been designed and launched to address these knowledge gaps.