In May 2003, the US Congress approved, and President George W. Bush signed into law, the United States Leadership Against HIV/AIDS, Tuberculosis, and Malaria Act of 20031 (Public Law 108-25). The Act authorized $15 billion over the 5-year period fiscal year (FY) 2004–2008 to combat HIV/AIDS through an initiative known as the President's Emergency Plan for AIDS Relief (PEPFAR). A remarkable coalition of government, nongovernmental organizations, civil society, the faith sector, and others came together to support this massive increase in foreign aid funding for HIV prevention, care, and treatment. PEPFAR began with the 3 following goals: treatment for 2 million people living with HIV (PLWH), the prevention of 7 million new infections, and provision of care for 10 million people infected and affected by HIV/AIDS, including orphans and vulnerable children, by 2008 (the “2-7-10” goals).
At the beginning of PEPFAR, little was known about the dynamics of the HIV pandemic, especially in the generalized epidemics of sub-Saharan Africa. Before 2003, only 3 countries had conducted surveys that provided population-based estimates of HIV prevalence.2–4 Limited routine antenatal surveillance data were available, and detailed epidemiologic information was often lacking. Additionally, the toolbox for prevention of sexual transmission was largely limited to behavioral strategies and to use of condoms. Interventions in countries such as Cambodia, the Dominican Republic, Thailand, and Uganda indicated that promoting behaviors aimed at risk avoidance and risk reduction would likely avert new infections and reduce the spread of HIV.5,6 The measurable declines achieved through local behavior change efforts in these countries and elsewhere informed the commitment of PEPFAR to implement prevention strategies responsive to local needs, local epidemiology, and distinctive social and cultural patterns.
PEPFAR'S INITIAL STRATEGY FOR PREVENTION OF SEXUALLY TRANSMITTED HIV: THE “ABSTINENCE, BE FAITHFUL, AND CORRECT AND CONSISTENT CONDOM USE” APPROACH
The first phase of PEPFAR sought to prevent 7 million HIV infections by 2010 in 15 “focus” countries. Young people were an important initial focus of PEPFAR prevention efforts because many of these countries have a youthful population profile and young people represent a window of opportunity for reversing the epidemic. Early evidence suggested that girls and young women in countries with high HIV prevalence tended to be at significantly elevated risk compared with their male peers.7,8 In some communities, as many as 20% of girls aged 15–19 were infected, compared with 5% of boys the same age.9 Coupled with high prevalence among older men, this pattern pointed to transmission fueled by cross-generational sex, a pattern which persists today.10,11,12 These data also came to influence PEPFAR investments in the first phase of the program.
To “jump-start” the scale-up of programs, PEPFAR fast-tracked a set of programs in priority areas. These included abstinence-focused HIV prevention for youth; blood and injection safety; antiretroviral treatment (ART); and care for orphans and vulnerable children. In the area of sexual prevention, in 2004–2005, PEPFAR made multicountry awards through the US Agency for International Development totaling over $100 million to 14 nongovernmental and faith-based organizations for abstinence-focused youth programs.13 These programs were focused on 14 high prevalence countries in sub-Saharan Africa and the Caribbean that, together with Vietnam, were originally designated as focus countries for scale-up of PEPFAR prevention, care, and treatment activities. These centrally funded youth programs prioritized abstinence, delay of first sex and fidelity and monogamous relationships among youth in the general population, and sought to foster collective social norms emphasizing avoidance of risky sexual behavior. They also sought to reduce sexual coercion and violence, transactional and cross-generational sex, and other behaviors that increase vulnerability to HIV, especially among young women.
In the original legislation, a directive stipulated that of the 20% of overall funds that were allocated for prevention, 33% of prevention funds should be used to promote “abstinence-until-marriage”.1 PEPFAR interpreted this to encompass not only premarital abstinence (primarily aimed at youth), but also promotion of marital fidelity for adult populations across all generalized epidemic countries, contributing to the coining of the term “abstinence and be faithful” or “AB.” Later on in PEPFAR, centrally funded programs supported with “AB” funds piloted programs focused on changing male norms, reducing vulnerability of adolescent girls, and addressing alcohol abuse.
As US Government country teams received their first allocations of PEPFAR resources, they too expanded funding for similar programs in their respective countries.14 Interventions included mobilization of communities through peer education and school-based and workplace programs, engagement of local leaders, including the faith community, and the development and use of multiple targeted media channels, including television, radio, and print.
In early 2005, the PEPFAR program issued the first PEPFAR prevention guidance, reflecting the Abstinence, Be Faithful, and correct and consistent Condom use (“ABC”) approach to HIV/AIDS sexual prevention.15 The ABC approach was developed with the principles of being responsive to local needs and epidemiology and to social and cultural patterns. It employed population-specific interventions that emphasized abstinence for youth and other unmarried persons, including delay of sexual debut; mutual faithfulness and partner reduction for sexually active adults regardless of their marital or relationships status; and correct and consistent use of condoms by those whose behavior placed them at risk for transmitting or becoming infected with HIV.
The ABC approach was distinctive in that specific populations, the circumstances they faced, and specific behaviors were targeted for change. This targeted approach was designed to result in comprehensive and effective country prevention programs that helped individuals personalize risk and develop strategies to avoid risky behaviors. According to the ABC guidance, every PEPFAR-funded country program had to include all 3 elements of “ABC,” promoted strategically to appropriate populations and epidemic drivers.15 Thus, the optimal balance of ABC activities varied across countries according to the patterns of HIV transmission, identification of core transmitters, cultural and social norms, and other contextual factors.16
Key Populations in Concentrated Epidemic Countries
During the first phase of PEPFAR, activities in generalized epidemics emphasized risk avoidance especially among youth. However, in countries with lower HIV prevalence in the general population, PEPFAR continued to prioritize key populations among whom HIV was concentrated, including sex workers (SWs) and their clients, mobile male populations, men who have sex with men (MSM), and people who inject drugs. The experiences of Thailand, Cambodia, the Dominican Republic, Senegal, and other countries illustrated that targeted efforts to promote correct and consistent condom use with specific high-risk groups could help contain and even reverse concentrated epidemics.17,18 Effective programs for at-risk populations provided outreach, comprehensive prevention messages, condom information and provision, and referrals to HIV counseling and testing and other services. As rapid testing technologies for HIV became available, some of these programs were able to provide HIV counseling and testing directly. During this period, PEPFAR also continued to procure unprecedented numbers of condoms for distribution in highly-affected countries (Fig. 1). The US Government supplied a total of more than 2.2 billion condoms worldwide for HIV prevention from 2004 to 2008.19
Gender in HIV Prevention
PEPFAR recognized early the centrality of gender issues to HIV prevention.1,20 In many countries with generalized epidemics, women's lower social and economic status combined with their vulnerability to violence and their increased biological susceptibility to the virus set up a chain reaction of risk for HIV infection.21 PEPFAR staff quickly came to understand that these dynamics, although generating an extraordinary threat to women, were also placing men at risk, and thus focused investments in gender programming not only on addressing women's needs but also on mobilizing changes in norms for men and boys. Programs to address these gender dynamics sought to ensure gender equity in existing prevention, care, and treatment programs and also to address the underlying causes of gender disparity through increasing women's legal rights and protection, addressing gender norms with both male and female audiences, increasing women's access to income and productive resources, and reducing violence and coercion.22–24
Gender issues also shaped the dynamics of concentrated epidemics, especially where the key populations at risk were MSM and other sexual minorities, as well as SWs. Much of the stigma associated with these behaviors is derived from cultural norms about gender and sexuality. Indeed, MSM,25 transgendered individuals,26 and commercial SWs27 have been shown to be at increased risk for gender-based violence, and this combination of stigma and risk conspired to limit both access to and seeking of critical HIV prevention, care, and treatment. Although programs in the first phase of PEPFAR were acutely aware of the stigma and discrimination facing key populations, the links between these factors and broader gender issues gained more attention in later years, when the focus on gender-based violence expanded to include key populations.28
Given the biological and cultural risk factors for HIV acquisition among women, PEPFAR has invested in existing and new women-controlled technologies for HIV prevention. These include the purchase of nearly 55 million female condoms between 2004 and 2011 and major investments in microbicide research.29 Both of these methods hold promises and challenges as follows: correct and consistent condom use has proven difficult to maintain in established relationships and trials for microbicides have had conflicting results and await further studies to clarify their efficacy.30–32
Lessons Learned From PEPFAR's Early Prevention Approach
PEPFAR investments in sexual prevention contributed to the rapid scale-up of prevention efforts at the community-level. In FY 2004, PEPFAR reached an estimated 35.9 million people through community outreach programs to prevent sexual transmission using the ABC approach.33 In FY 2008, this number increased to a total of 58.3 million individuals reached through community outreach activities to prevent sexual transmission of HIV.34
Early prevention efforts were often uneven. Local partners often lacked the absorptive capacity and technical expertise to achieve sufficient coverage and quality of interventions. In some countries, the emphasis on abstinence for youth also resulted in a lack of strategic focus on the highest transmission areas and key epidemic drivers. Although youth remain an important target group in many generalized epidemics, the emphasis on youth prevention in the early years of PEPFAR was not always aligned with the country-specific epidemiology, sometimes resulting in inadequate attention to important adult populations. Moreover, early PEPFAR prevention efforts did not always adequately support the condom and partner reduction programming appropriate to older sexually-active populations, especially in contexts where marriage and cohabitation rates are low, relationships remain fluid.
Another key challenge facing PEPFAR were the innate tensions—politically and culturally, at home and abroad—surrounding HIV prevention. Navigating these effectively, especially in the absence of substantive data on incidence, has been complex and difficult; this challenge remains front and center for PEPFAR as it moves to bring newer interventions to scale.
Additionally, PEPFAR did not initially identify PLWH as a priority target group for prevention, although in domestic US programs, the Centers for Disease Control and Prevention had long designated this population as the highest priority for HIV prevention efforts.35 In 2006, PEPFAR provided funding to support the implementation and evaluation of pilot “positive health dignity and prevention” (PHDP) interventions aimed at providing comprehensive HIV prevention programs for PLWH and their partners in 3 countries, and has expanded these efforts since then. Bringing effective PHDP programs to scale continues to be a challenge, though the pace is increasing.
Condom availability also remained a challenge. Male and female condoms remain a highly efficacious option for prevention of sexual transmission, but consistent condom use is predicated upon a reliable widely available and accessible supply of condoms. In late 2010, a PEPFAR desk review of data on condom stockouts and shortages in high burden African countries identified large variations in condom availability among the 14 African countries for which data were available.36 The review also identified weaknesses in public sector supply chains, with frequent stockouts and/or shortages of condoms in the central medical warehouses over an 18-month period between 2008 and 2010 in the majority of countries for which data were available.
Finally, since 2004, there have been significant advances in understanding country-specific epidemics. These have resulted from availability of new epidemiological data on incidence and prevalence of HIV, the geographic hotspots of the epidemic, the drivers of transmission, the populations at highest risk of acquiring HIV, and HIV prevalence and incidence within specific subpopulations (Fig. 2). These data come from population-based surveys, modes of transmission studies, modeling, size estimation studies for key populations, and other qualitative and quantitative research, much of it supported by PEPFAR. For example, the recognition that in some parts of Africa an important source of new infections is transmission within long-standing serodiscordant couples emerged from population-based HIV prevalence surveys.37
In growing collaboration with partner countries, PEPFAR country teams have recognized and responded to identified drivers of infections and programmatic gaps, taking steps to better align their sexual prevention efforts with country epidemiology. In response to new data, country programs have increased attention to key populations and epidemic drivers and are working toward coordinating more systematic coverage through mapping exercises focusing on geographic hot spots.38 They are also working to improve the quality of behavioral prevention efforts, by adopting evidence-based or best practice and standardized behavioral interventions, and by building local capacity in prevention. A number of countries have addressed gaps in programming for high-risk populations and for prevention for PLWH and discordant couples; several have systematically integrated PHDP programs within HIV care and treatment services nationally.39,40
Measurement has remained a key challenge for PEPFAR behavioral prevention programs. Program monitoring has largely focused on outputs, measuring numbers “reached.” The second generation of PEPFAR indicators sought to incorporate parameters to ensure that programs are reaching people with interventions that meet minimum standards of quality, but the essential challenge of better understanding program effectiveness remains. More rigorous evaluation of outcomes and impacts and better tools to assess program quality and coverage are needed to advance the field of HIV prevention, especially with respect to behavioral interventions for the general population.41,42 PEPFAR has made a substantial investment in 3 rigorously designed community trials of prevention to measure the impact of combination prevention interventions. These trials will assist in improved approaches to program design and monitoring in the future.43
At a higher level, the question of impact of particular programs on reducing incidence is unknown. Absent an effective incidence marker, it has been difficult to assess progress on PEPFAR's original goal of preventing 7 million new infections. According to analysis by UNAIDS, incident HIV infections peaked in 1999 in much of sub-Saharan Africa.44 This has been followed by declines in overall prevalence, culminating in greater than 25% declines in prevalence among young people in 15 high-burden countries by 2009.45 Further analyses using the GOALS model46 also show substantial decreases in incidence in the most heavily burdened African countries, though whether these decreases result from interventions or arise naturally as the epidemics run their course is difficult to say (Figs. 2, 3). Prevalence remained relatively steady in most of these countries, a finding that could result in part from a combined effect of reduced incidence and mortality. Zimbabwe is an exception; recent modeling suggests that the reductions in both incidence and prevalence there result from changes in behavior during the recent period of social and economic unrest.47 Some data suggest that changes in behavior played a role in incidence declines. A recent analysis by the International Group on Analysis of Trends in HIV Prevalence and Behaviors among Young People found delayed onset of sexual activity, reduction in the number of sexual partners, and increased condom use in some of the countries that saw declines in incidence.48 PEPFAR's prevention programs were active in many of these countries and self-reports of behavior change from DHS+ surveys in those countries suggest the possibility that these programs did influence sexual debut, number of partners, and use of condoms. However, the evidential links from self-reported behavior to actual behavior to incidence reduction are difficult to make.49 The scale-up of ART likely also played a role in declining incidence. The lack of incidence data at the onset of PEPFAR programs means we may never know conclusively the contribution of these activities to reduced infections (Fig. 4).
PEPFAR'S SECOND PHASE STRATEGY: COMBINATION PREVENTION
In July 2008, PEPFAR was reauthorized with important modifications to the legislative language on prevention.50 Most significantly, the overarching abstinence-until-marriage budgetary requirement was dropped. The revised legislation stipulates that when PEPFAR programs in countries with generalized epidemics spend less than 50% of their sexual prevention budget on abstinence and faithfulness programming, they must submit a justification in their country operational plan. In 2009, PEPFAR issued its second 5-Year HIV Prevention Strategy, which seeks to support the prevention of more than 12 million new HIV infections, and endorses a combination prevention approach for all PEPFAR country programs to achieve this goal.51 Predicated on the idea that no single intervention is efficacious enough to bring an HIV epidemic under control on its own, the combination prevention approach reflects both the recognition that there is no “silver bullet” for HIV prevention and a growing emphasis on the importance of an optimal set of interventions to reduce HIV incidence.
This emphasis on inclusion of evidence-based interventions stems partly from a wave of new research findings demonstrating the efficacy of certain biomedical interventions. In 2007, 3 randomized controlled trials found that voluntary medical male circumcision (VMMC) has an approximately 60% protective effect against HIV acquisition in men during heterosexual intercourse.52–54 New data demonstrated that PLWH taking antiretroviral drugs correctly and consistently are 96% less likely to transmit the virus to their HIV discordant sexual partners than those not on treatment.55–57 And several studies showed partial efficacy of oral antiretroviral prophylaxis for uninfected individuals, though these data are more mixed.58
In the wake of these findings the discussion within PEPFAR turned to the appropriate allocation of resources across different prevention interventions. In November 2010, before the publication of HPTN 052 or oral PrEP studies showing the impact of ART on HIV transmission,57,59 PEPFAR convened a consultation on “unresolved issues in HIV prevention in generalized epidemics” to inform this discussion. Experts in various aspects of HIV prevention were invited to weigh the different types of evidence, and to discuss how to determine the appropriate mix and prioritization of interventions in different settings, and how to combine interventions to maximize synergies at scale.60 The consultation focused on areas where consensus was lacking either on the evidence itself or on the appropriate standard of evidence. The conference found that the evidence was strongest for a set of “core interventions”: VMMC, comprehensive programs for PLWH and key populations at high risk, and condoms [and for prevention of mother-to-child transmission (PMTCT), as an approach for nonsexual transmission prevention]. The consultation also recognized that treatment would play a critical role in reducing new infections and that behavioral interventions to support these core interventions and reduce risk are critical. PEPFAR leadership drew upon these findings to develop new PEPFAR guidance on prevention of sexual transmission,61 which translated these findings into a combination prevention approach. PEPFAR issued this “Guidance for the Prevention of Sexually Transmitted HIV Infections” in August 2011. Previous guidelines addressed combination prevention for people who inject drugs (July 2010) and men who have sex with men (May 2011).62,63
In November of 2011, Secretary of State Hillary Rodham Clinton gave a landmark speech setting the goal of an “AIDS-free generation.” She defined this as a world in which “virtually no children are born with the virus; second, as these children become teenagers and adults, they are at far lower risk of becoming infected than they would be today thanks to a wide range of prevention tools; and third, if they do acquire HIV, they have access to treatment that helps prevent them from developing AIDS and passing the virus on to others.”64 This speech was followed by President Obama's announcement on World AIDS Day, 2011, of new PEPFAR targets for PMTCT, VMMC, treatment and condom procurement.65 Together, these statements and commitments and the PEPFAR guidance reflect the current chapter on PEPFAR's efforts on HIV prevention. PEPFAR prevention portfolio in high-prevalence epidemics is shifting to focus more directly on these high-impact interventions, with programs aimed at risk reduction and condom use integrated within the behavioral demand creation messaging that supports them.
Meeting these targets presents significant challenges. The AIDS free generation goal raises many questions still unanswered and ushers in a new policy and set of challenges that will define the debate over prevention looking forward. Forging effective partnerships with countries will remain critical for sustainable success in prevention. For example, bringing VMMC, treatment and PMTCT interventions to scale will stress fragile country commodity and supply chains, and increase the burden on limited human resources for health. Yet similar challenges characterized PEPFAR's initial forays into providing treatment in low-resource settings. Nine years later, more than 4 million people living in low-resource settings are on treatment and many more are alive, thanks to PEPFAR-supported programs. Many countries are stepping up with growing commitment and capacity.
PEPFAR's history shows that major accomplishments in global health are possible with a focus on results. The next 2 years will be a critical test of this premise, as PEPFAR moves into the next chapter of HIV prevention.
2. Cellule de Planification et de Statistique, Ministère de la Santé, Direction Nationale de la Statistique et de l'Informatique (DNSI) and ORC Macro. HIV Testing in Mali: Findings From the 2001 Mali Demographic and Health Survey. MD: Cellule de Planification et de Statistique, Ministère de la Santé, Direction Nationale de la Statistique et de l'Informatique (DNSI) and ORC Macro; Bamako, Mali, 2002.
3. Shisana O, Simbayi L. Nelson Mandela/HSRC Study of HIV/AIDS: South African National HIV Prevalence, Behavioural Risks and Mass Media—Household Survey 2002. Cape Town, South Africa: Human Sciences Research Council; 2002.
4. Central Statistical Office. Central Board of Health, and ORC Macro. Zambia Demographic and Health Survey 2001–2002: Preliminary Report. Calverton, MD: Central Statistical Office, Central Board of Health, and ORC Macro; 2002.
5. Stoneburner R, Low-Beer D. Population-level HIV declines and behavioral risk avoidance in Uganda. Science. 2004;304:714–718.
6. Measure Evaluation. Sexual Behavior, HIV and Fertility Trends: A Comparative Analysis of Six Countries. Washington, DC: USAID; 2003.
7. Fylkesnes K, Musonda RM, Kasumba K, et al.. The HIV epidemic in Zambia: socio-demographic prevalence patterns and indications of trends among childbearing women. AIDS. 1997;11:339–345.
8. Gregson S, Nyamukapa CA, Garnett GP, et al.. HIV infection and reproductive health in teenage women orphaned and made vulnerable by AIDS in Zimbabwe. AIDS Care. 2005;17:785–794.
9. Kelly RJ, Gray RH, Sewankambo NK, et al.. Age differences in sexual partners and risk of HIV-1 infection in rural Uganda. J Acquir Immune Defic Syndr. 2003;32:446–451.
10. Glynn, Caraöl M, Auvert B, et al.. Why do young women have a much higher prevalence of HIV than young men? A study in Kisumu, Kenya and Ndola, Zambia. AIDS. 2001;15(suppl 4):S51–S60.
11. Luke N, Kurz K. Cross-Generational and Transactional Sexual Relations in Sub-Saharan Africa. Washington, DC: AIDSmark; 2002.
12. Wilson D. Partner reduction and the prevention of HIV/AIDS: the most effective strategies come from communities. BMJ. 2004;328:848–849.
13. USAID Press Release. “$100 Million in Abstinence-Focused Grants for HIV/AIDS Prevention Awarded Under President Bush's Emergency Plan for AIDS Relief: Faith-Based Community Plays Key Role in Expansion”. October 5, 2004 Washington, DC: USAID; 2004.
16. Cates W. The “ABC to Z” approach: condoms are one element in a comprehensive approach to STI/HIV prevention. Network. 2003;22:4.
17. Merson MH, Dayton JM, O'Reilly K. Effectiveness of HIV prevention interventions in developing countries. AIDS. 2000;14(suppl 2):S68–S84.
18. Stover J, Walker N, Garnett GP, et al.. Can we reverse the HIV/AIDS pandemic with an expanded response. Lancet. 2002;360:73–77.
20. Dunkle KL, Jewkes RK, Brown HC, et al.. Gender-based violence, relationship power, and risk of HIV infection in women attending antenatal clinics in South Africa. Lancet. 2004;363:1415–1421.
21. Quinn TC, Overbaugh J. HIV/AIDS in women: an expanding epidemic. Science. 2005:308;1582–1583.
22. Kim J, Pronyk P, Barnett T, et al.. Exploring the role of economic empowerment in HIV Prevention. AIDS. 2008;22(suppl 4):S57–S71.
23. Jewkes R, Nduna M, Levin J, et al.. Impact of stepping stones on incidence of HIV and HSV-2 and sexual behavior in rural South Africa: cluster randomized control trial. BMJ. 2008;337:a506.
24. Lecler-Madlala S. Age-disparate and intergenerational sex in southern Africa: the dynamics of hypervulnerability. AIDS. 2008;22(suppl 4):S17–S25.
25. Greenwood GL, Relf MV, Huang B, et al.. Battering victimization among a probability-based sample of men who have sex with men. Am J Public Health. 2002;92:1964–1969.
26. Guadamuz T, Wimonsate W, Varangrat A, et al.. Correlates of forced sex among populations of men who have sex with men in Thailand. Arch Sex Behav. 2009:40:1–8.
27. Shannon K, Csete J. Violence, condom negotiation, and HIV/STI risk among sex workers. JAMA. 2010;304:573–574.
30. Karim QA, Karim SS, Frochlich JA, et al.. Effectiveness and safety of tenofovir gel, an antiretroviral microbicide, for the prevention of HIV infection in women. Science. 2010;329:1168–1174.
31. McCormack S, Ramjee G, Kamali A, et al.. PRO2000 vaginal gel for prevention of HIV-1 infection (Microbicides Development Programme 301): a phase 3randomised, double-blind, parallel-group trial. Lancet. 2010;376:1329–1337.
32. Skoler-Karpoff S, Ramjee G, Ahmed K, et al.. Efficacy of Carraguard for prevention of HIV infection in women in South Africa: A randomised, double-blind, placebo-controlled trial. Lancet. 2008;372:1977–1987.
35. Centers for Disease Prevention and Control. Incorporating HIV Prevention into the Medical Care of Persons Living with HIV: Recommendations of CDC, the Health Resources and Services Administration, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. Atlanta, GA: CDC Recommendations and Reports; 2003;52;1–24.
36. USAID. Is There a Condom Gap in 2010? A Review of Condom Availability, Accessibility and Acceptability in Sub-Saharan Africa. Washington, DC: USAID; 2010.
37. Kaiser R, Bunnell R, Hightower A, et al.. Factors associated with HIV infection in married and cohabitating couples in Kenya: Results from a nationally representative study. PLoS One. 2011;6:e17842.
39. Dunkle KM, Stephenson R, Karita E, et al.. New heterosexually transmitted HIV infections in married or cohabitating couples in urban Zambia and Rwanda: an analysis of survey and clinical data. Lancet. 2008;371:2183–2191.
40. Burton J, Dares L, et al.. Couples-focused behavioral interventions for prevention of HIV: systematic review of the state of the evidence. AIDS and Behav. 2010;14:1–10.
41. Hankins CA, de Zalduondo BO. Combination prevention: a deeper understanding of effective HIV prevention. AIDS. 2010;24:S70.
47. Halperin DT, Mugurungi O, Hallett TB, et al.. A surprising prevention success: why did the HIV epidemic decline in Zimbabwe? PLoS Med. 2011;8:e1000414.
48. Ghys PD, Gouws E, et al.. Trends in HIV prevalence and sexual behaviour among young people aged 15–24 years in countries most affected by HIV. Sex Transm Infect. 2010;86(suppl 2):ii72–ii83.
49. Padian NS, McCoy SI, et al.. Weighing the gold in the gold standard: challenges in HIV prevention research. AIDS. 2010;24:621–635.
50. H.R. 5501 (110th): Tom Lantos and Henry J. Hyde United States Global Leadership Against HIV/AIDS, Tuberculosis, and Malaria Reauthorization Act of 2008. 110th Congress, 2007–2009. Available at: http://www.govtrack.us/congress/bills/110/hr5501
. Accessed June 18, 2012.
52. Gray RH, Kigozi G, et al.. Male circumcision for HIV prevention in men in Rakai, Uganda: a randomized trial. Lancet. 2007;369:657–666.
53. Bailey RC, Moses S, Parker CB, et al.. Male circumcision for HIV prevention in young men in Kisumu, Kenya: a randomised controlled trial. Lancet. 2007;369:643–656.
54. Auvert B, Taljaard D, Lagarde E, et al.. Randomized, controlled intervention trial of male circumcision for reduction of HIV infection risk: the ANRS 1265 trial. PLoS Med. 2005;2:e298.
55. Donnell D, Baeten JM, Kiarie J, et al.. Heterosexual HIV-1 transmission after initiation of antiretroviral therapy: a prospective cohort analysis. Lancet. 2010;375:2092–2098.
56. Powers KA, Poole C, Pettifor AE, et al.. Rethinking the heterosexual infectivity of HIV-1: a systematic review and meta-analysis. Lancet Infect Dis. 2008;8:553–563.
57. Cohen MS, Chen YQ, McCauley M, et al.. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med. 2011;365:493–505.
58. Kashuba ADM, Patterson KB, Dumond JB, et al.. Pre-exposure prophylaxis for HIV prevention: How to predict success. Lancet. E-pub: December 7, 2011. doi:10.1016/S0140-6736(11)61852-7.
59. Grant RM, Lama JR, Anderson PL, et al.. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med. 2010;363:2587–2599.
60. Office of the U.S. Global AIDS Coordinator. PEPFAR Expert Consultation on Unresolved Issues in HIV Prevention Programming in Generalized Epidemics. Available at: http://www.pepfar.gov/meetings/166177.htm
. Washington, DC. Accessed November 8–9, 2010.
61. Office of the U.S. Global AIDS Coordinator. Guidance for the Prevention of Sexually Transmitted HIV Infections for the President's Emergency Plan for AIDS Relief. Washington, DC; 2011. Available at: http://www.pepfar.gov/guidance/171094.htm
. Accessed June 18, 2012.
Keywords:© 2012 Lippincott Williams & Wilkins, Inc.