Evaluation of Large-Scale Combination HIV Prevention Programs: Essential Issues

Assessing Direct and Spillover Effects of Intervention Packages in Network-randomized Studies

BACKGROUND

Intervention packages may result in a greater public health impact than single interventions. Understanding the separate impact of each component on the overall package effectiveness can improve intervention delivery.

METHODS

We adapted an approach to evaluate the effects of a time-varying intervention package in a network-randomized study. In some network-randomized studies, only a subset of participants in exposed networks receive the intervention themselves. The spillover effect contrasts average potential outcomes if a person was not exposed to themselves under intervention in the network versus no intervention in a control network. We estimated the effects of components of the intervention package in HIV Prevention Trials Network 037, a Phase III network-randomized HIV prevention trial among people who inject drugs and their risk networks using marginal structural models to adjust for time-varying confounding. The index participant in an intervention network received a peer education intervention initially at baseline, then boosters at 6 and 12 months. All participants were followed to ascertain HIV risk behaviors.

RESULTS

There were 560 participants with at least one follow-up visit, 48% of whom were randomized to the intervention, and 1,598 participant visits were observed. The spillover effect of the boosters in the presence of initial peer education training was a 39% rate reduction (rate ratio = 0.61; 95% confidence interval = 0.43, 0.87).

CONCLUSIONS

These methods will be useful for evaluating intervention packages in studies with network features.

Assessing Direct and Spillover Effects of Intervention Packages in Network-Randomized Studies

Intervention packages may result in a greater public health impact than single interventions. Understanding the separate impact of each component in the overall package effectiveness can improve intervention delivery. We adapted an approach to evaluate the effects of a time-varying intervention package in a network-randomized study. In some network-randomized studies, only a subset of participants in exposed networks receive the intervention themselves. The spillover effect contrasts average potential outcomes if a person was not exposed themselves under intervention in the network versus no intervention in a control network. We estimated effects of components of the intervention package in HIV Prevention Trials Network 037, a Phase III network-randomized HIV prevention trial among people who inject drugs and their risk networks using Marginal Structural Models to adjust for time-varying confounding. The index participant in an intervention network received a peer education intervention initially at baseline, then boosters at 6 and 12 months. All participants were followed to ascertain HIV risk behaviors. There were 560 participants with at least one follow-up visit, 48% of whom were randomized to the intervention, and 1,598 participant-visits were observed. The spillover effect of the boosters in the presence of initial peer education training was a 39% rate reduction (Rate Ratio = 0.61; 95% confidence interval= 0.43, 0.87). These methods will be useful to evaluate intervention packages in studies with network features.

Programme science: a route to effective coverage and population-level impact for HIV and sexually transmitted infection prevention

Improvements in context-specific programming are essential to address HIV and other sexually transmitted and blood-borne infection epidemics globally. A programme science approach emphasises the need for context-specific evidence and knowledge, generated on an ongoing basis, to inform timely and appropriate programmatic decisions. We aim to accelerate and improve the use of embedded research, inquiry, and learning to optimise population-level impact of public health programmes and to introduce an effective programme coverage framework as one tool to facilitate this goal. The framework was developed in partnership with public health experts in HIV and sexually transmitted and blood-borne infections through several workshops and meetings. The framework is a practice-based tool that centres on the use of data from iterative cycles of programme-embedded research and learning, as well as routine programme monitoring, to refine the strategy and implementation of a programme. This programme science approach aims to reduce programme coverage gaps, to optimise impact at the population level, and to achieve effective coverage. This framework should facilitate the generation of programme-embedded research and learning agendas to inform resource allocation, optimise population-level impact, and achieve equitable and effective programme coverage.

The First 40 Years of AIDS: Promising Programs, Limited Success

HIV-prevention program planning, implementation, and evaluation began in the United States shortly after reports of a mysterious, apparently acquired, immune deficiency syndrome appeared in summer 1981. In San Francisco, New York City, and elsewhere, members of LGBT communities responded by providing accurate information, giving support, and raising money. During the first decade of the AIDS pandemic (1981-1990), social and behavioral scientists contributed by designing theory-based and practical interventions, combining interventions into programs, and measuring impact on behavior change and HIV incidence. In the second decade (1991-2000), federal, state, and local agencies and organizations played a more prominent role in establishing policies and procedures, funding research and programs, and determining the direction of intervention efforts. In the third decade (2001-2010), biomedical interventions were prioritized over behavioral interventions and have dominated attempts in the fourth decade (2011-2020) to integrate biomedical, behavioral, and structural interventions into coherent, efficient, and cost-effective programs to end AIDS.

A longitudinal qualitative evaluation of an economic and social empowerment intervention to reduce girls' vulnerability to HIV in rural Mozambique

PURPOSE

An intervention including business training and health education was implemented in Mozambique, where girls are at elevated risk for acquiring HIV. As part of a mixed-methods evaluation, we describe perceived effects of the intervention on girls' sexual behavior and school attendance.

METHODS

We conducted 49 in-depth interviews (IDIs) with girl intervention participants (ages 13-19), 24 IDIs with heads of girls' households, 36 IDIs with influential males identified by girls, and 12 focus group discussions with community members after the intervention ended and one year later.

RESULTS

Informants said the primary intervention benefit was realized when girls had money to stay in or return to school and/or to buy necessities for themselves and their households-reducing their need for transactional or intergenerational sex. However, some girls did not make a profit and some businesses were not sustainable. Sometimes the intervention appeared to be implemented in a way to reinforce inequitable gender norms resulting in some girls feeling shame when they reengaged in risky sex after their businesses failed.

CONCLUSIONS

Earning money enabled girls to potentially reduce their vulnerability to HIV. We offer recommendations for future multi-sector interventions, including the need to address potential harms in programs serving vulnerable girls.

Quasi-experimental evaluation using confirmatory procedures: A case study of an economic and social empowerment intervention to reduce girls' vulnerability to HIV in rural Mozambique

PURPOSE

Our goal was to determine whether an economic and social empowerment intervention implemented in Zambézia Province, Mozambique reduced girls' vulnerability to HIV. We use this experience to discuss challenges of evaluating real-world interventions.

METHODS

Two rounds of data were collected from 885 girls, 13-19 years, for this clustered, non-equivalent (two-stage) cohort trial. We used multi-level exact matching and difference-in-differences estimation to estimate intervention effects on two outcomes: girls' knowledge of gender-based violence and school attendance.

RESULTS

Estimates of two outcomes analysed indicated no statistically significant intervention effects. Preliminary analysis of data from the intervention group revealed this study was unable to obtain accurate measures for five outcomes related to HIV vulnerability.

CONCLUSIONS

Although our study did not find evidence of impact on the a priori selected outcomes, we report on our experience implementing this robust methodologic design and describe how the challenges encountered in this program setting affected our ability to attain results. We recommend prospective evaluation designs with random allocation be accommodated early during planning. When not possible, quasi-experimental studies should collect data from large samples. To reduce measurement bias, biological endpoints such sexually transmitted infections should serve as primary outcomes for programs intending to reduce sexual behaviors.

Altered Toll-Like Receptor-4 Response to Lipopolysaccharides in Infants Exposed to HIV-1 and Its Preventive Therapy

Pathogen sensing and recognition through pattern recognition receptors, and subsequent production of pro-inflammatory cytokines, is the cornerstone of the innate immune system. Despite the fact that HIV-exposed uninfected (HEU) infants are prone to serious bacterial infections, no study has focused on the functionality of their bacteria recognition system. This is the first study to investigate baseline levels of three critically important immune response molecules in this population: complement component (C)-3, toll-like receptor (TLR)-4, and C-reactive protein (CRP). We enrolled 16 HEU and 6 HIV-unexposed (HU) infants. TLR4 function was investigated by stimulating whole blood with increasing concentrations of TLR4-agonist ultrapure lipopolysaccharides. TLR4/TLR4-agonist dose response were assessed by measuring IL-6 secretion. Complement C3 and CRP were measured by photo spectrometry. Data showed no significant differences in baseline concentration of CRP between HEU and HU infants. Complement C3 was significantly higher in HEU infants than HU infants. TLR4 anergy was observed in 7 of 12 HEU infants, whereas the rest of HEU infants (n = 4) and the control HU infants tested (n = 3) showed responsive TLR4. None of the HEU infants investigated in this study had severe infections in the year after their birth. In conclusion, TLR4 anergy can occur in HEU infants without necessarily translating to increased vulnerability to infectious diseases.

Mother-to-child HIV-transmission prevention programs in a sub-Saharan African setting: The Gabonese experience

In many developing countries, mothers' awareness remains a challenge despite the scaling up of antenatal care and programs preventing mother-to-child (MTC) HIV transmission. The present study was done in Libreville, Gabon where all antenatal care (delivery included) is free of charge. Here we assessed the timing of antenatal antiretroviral (ARV) prophylaxis initiation, HIV-exposed infants' age at their first postnatal HIV check visit and investigated the association between mothers' awareness or knowledge on their ARV therapy and infants' HIV infection. We interviewed HIV-positive mothers on their first and subsequent laboratory visits to investigate infants' HIV status and tested infants for HIV RNA and antibody between 2012 and 2014. We established that (1) of 718 HIV-positive mothers, only 6% were fully aware and knew what ARV treatment they were on during pregnancy; (2) half of the women (54%) start their antenatal ARV prophylaxis initiation during the second trimester of pregnancy; (3) 64% of HIV-exposed infants had their first HIV infection screening between birth and three months of age; (4) the overall prevalence of HIV infection in infants born from infected mothers was 8.9%; and (5) infants born from mothers uncertain about taking prophylactic ARV therapy were 13.3 times more likely to be infected by HIV than infants born from mothers certain about taking prophylactic ARV therapy. In conclusion, the study showed that despite free antenatal care, early access and adherence to components of MTC, HIV transmission preventive care remains unsatisfactory.

Effectiveness of combination packages for HIV-1 prevention in sub-Saharan Africa depends on partnership network structure: a mathematical modelling study

OBJECTIVES

Combination packages for HIV prevention can leverage the effectiveness of biomedical and behavioural elements to lower disease incidence with realistic targets for individual and population risk reduction. We investigated how sexual network structures can maximise the effectiveness of a package targeting sexually active adults in sub-Saharan Africa (SSA) with intervention components for medical male circumcision (MMC) and sexual partnership concurrency (having >1 ongoing partner).

METHODS

Network-based mathematical models of HIV type 1 (HIV-1) transmission dynamics among heterosexual couples were used to explore how changes to MMC alone and in combination with changes to concurrency impacted endemic HIV-1 prevalence and incidence. Starting from a base model parameterised from empirical data from West Africa, we simulated the prevalence of circumcision from 10% to 90% and concurrency was modelled at four discrete levels corresponding to values observed across SSA.

RESULTS

MMC and concurrency could contribute to the empirical variation in HIV-1 disease prevalence across SSA. Small reductions in concurrency resulted in large declines in HIV-1 prevalence. Scaling up circumcision in low-concurrency settings yields a greater relative benefit, but the absolute number of infections averted depends on both the circumcision coverage and baseline incidence. Epidemic extinction with this package will require substantial scale-up of MMC in low-concurrency settings.

CONCLUSIONS

Dynamic sexual network structure should be considered in the design and targeting of MMC within combination HIV-1 prevention packages. Realistic levels of coverage for these packages within southern Africa could lead to a reduction of incidence to the low levels observed in western Africa, and possibly, epidemic extinction.

A Rights-Based Sexuality Education Curriculum for Adolescents: 1-Year Outcomes From a Cluster-Randomized Trial

PURPOSE

The purpose of this study was to evaluate the impact of a rights-based sexuality education curriculum on adolescents' sexual health behaviors and psychosocial outcomes 1 year after participation.

METHODS

Within 10 urban high schools, ninth-grade classrooms were randomized to receive a rights-based curriculum or a basic sex education (control) curriculum. The intervention was delivered across two school years (2011-2012, 2012-2013). Surveys were completed by 1,447 students at pretest and 1-year follow-up. Multilevel analyses examined curriculum effects on behavioral and psychosocial outcomes, including four primary outcomes: pregnancy risk, sexually transmitted infection risk, multiple sexual partners, and use of sexual health services.

RESULTS

Students receiving the rights-based curriculum had higher scores than control curriculum students on six of nine psychosocial outcomes, including sexual health knowledge, attitudes about relationship rights, partner communication, protection self-efficacy, access to health information, and awareness of sexual health services. These students also were more likely to report use of sexual health services (odds ratio, 1.37; 95% confidence interval, 1.05-1.78) and more likely to be carrying a condom (odds ratio, 1.97; 95% confidence interval, 1.39-2.80) relative to those receiving the control curriculum. No effects were found for other sexual health behaviors, possibly because of low prevalence of sexual activity in the sample.

CONCLUSIONS

The curriculum had significant, positive effects on psychosocial and some behavioral outcomes 1 year later, but it might not be sufficient to change future sexual behaviors among younger adolescents, most of whom are not yet sexually active. Booster education sessions might be required throughout adolescence as youth initiate sexual relationships.

Advances in HIV prevention for serodiscordant couples

Serodiscordant couples play an important role in maintaining the global HIV epidemic. This review summarizes biobehavioral and biomedical HIV prevention options for serodiscordant couples focusing on advances in 2013 and 2014, including World Health Organization guidelines and best evidence for couples counseling, couple-based interventions, and the use of antiviral agents for prevention. In the past few years, marked advances have been made in HIV prevention for serodiscordant couples and numerous ongoing studies are continuously expanding HIV prevention tools, especially in the area of pre-exposure prophylaxis. Uptake and adherence to antiviral therapy remains a key challenge. Additional research is needed to develop evidence-based interventions for couples, and especially for male-male couples. Randomized trials have demonstrated the prevention benefits of antiretroviral-based approaches among serodiscordant couples; however, residual transmission observed in recognized serodiscordant couples represents an important and resolvable challenge in HIV prevention.

The promises and challenges of pre-exposure prophylaxis as part of the emerging paradigm of combination HIV prevention

INTRODUCTION

Towards the end of the twentieth century, significant success was achieved in reducing incidence in several global HIV epidemics through ongoing prevention strategies. However, further progress in risk reduction was uncertain. For one thing, it was clear that social vulnerability had to be addressed, through research on interventions addressing health systems and other structural barriers. As soon as antiretroviral treatment became available, researchers started to conceive that antiretrovirals might play a role in decreasing either susceptibility in uninfected people or infectiousness among people living with HIV. In this paper we focus on the origin, present status, and potential contribution of pre-exposure prophylaxis (PrEP) within the combination HIV prevention framework.

DISCUSSION

After a phase of controversy, PrEP efficacy trials took off. By 2015, daily oral PrEP, using tenofovir alone or in combination with emtricitabine, has been proven efficacious, though efficacy seems heavily contingent upon adherence to pill uptake. Initial demonstration projects after release of efficacy results have shown that PrEP can be implemented in real settings and adherence can be high, leading to high effectiveness. Despite its substantial potential, beliefs persist about unfeasibility in real-life settings due to stigma, cost, adherence, and potential risk compensation barriers.

CONCLUSIONS

The strategic synergy of behavioural change communication, biomedical strategies (including PrEP), and structural programmes is providing the basis for the combination HIV prevention framework. If PrEP is to ever become a key component of that framework, several negative beliefs must be confronted based on emerging evidence; moreover, research gaps regarding PrEP implementation must be filled, and appropriate prioritization strategies must be set up. Those challenges are significant, proportional to the impact that PrEP implementation may have in the global response to HIV.

Effectiveness of a combination prevention strategy for HIV risk reduction with men who have sex with men in Central America: a mid-term evaluation

BACKGROUND

Despite over a decade of research and programming, little evidence is available on effective strategies to reduce HIV risks among Central American men who have sex with men (MSM). The Pan-American Social Marketing Organization (PASMO) and partners are implementing a HIV Combination Prevention Program to provide key populations with an essential package of prevention interventions and services: 1) behavioral, including interpersonal communications, and online outreach; 2) biomedical services including HIV testing and counseling and screening for STIs; and 3) complementary support, including legal support and treatment for substance abuse. Two years into implementation, we evaluated this program's effectiveness for MSM by testing whether exposure to any or a combination of program components could reduce HIV risks.

METHODS

PASMO surveyed MSM in 10 cities across Guatemala, El Salvador, Nicaragua, Costa Rica, and Panama in 2012 using respondent-driven sampling. We used coarsened exact matching to create statistically equivalent groups of men exposed and non-exposed to the program, matching on education, measures of social interaction, and exposure to other HIV prevention programs. We estimated average treatment effects of each component and all combined to assess HIV testing and condom use outcomes, using multivariable logistic regression. We also linked survey data to routine service data to assess program coverage.

RESULTS

Exposure to any program component was 32% in the study area (n = 3531). Only 2.8% of men received all components. Men exposed to both behavioral and biomedical components were more likely to use condoms and lubricant at last sex (AOR 3.05, 95% CI 1.08, 8.64), and those exposed to behavioral interventions were more likely to have tested for HIV in the past year (AOR 1.76, 95% CI 1.01, 3.10).

CONCLUSIONS

PASMO's strategies to reach MSM with HIV prevention programming are still achieving low levels of population coverage, and few men are receiving the complete essential package. However, those reached are able to practice HIV prevention. Combination prevention is a promising approach in Central America, requiring expansion in coverage and intensity.

The heterogeneous effects of HIV testing

An extensive multi-disciplinary literature examines the effects of learning one's HIV status on subsequent risky sexual behaviors. However, many of these studies rely on non-experimental designs; use self-reported outcome measures; or both. In this study, we investigate the effects of a randomly assigned home based HIV testing and counseling (HTC) intervention on risky sexual behaviors and schooling investments among school-age females in Malawi. We find no overall effects on HIV, Herpes Simplex Virus (HSV-2), or achievement test scores at follow-up. However, among the small group of individuals who tested positive for HIV, we find a large increase in the probability of HSV-2 infection, with this effect being stronger among those surprised by their test results. Similarly, those surprised by HIV-negative test results have significantly higher achievement test scores at follow-up, consistent with increased returns to investments in human capital.

Transformation of HIV from pandemic to low-endemic levels: a public health approach to combination prevention

Large declines in HIV incidence have been reported since 2001, and scientific advances in HIV prevention provide strong hope to reduce incidence further. Now is the time to replace the quest for so-called silver bullets with a public health approach to combination prevention that understands that risk is not evenly distributed and that effective interventions can vary by risk profile. Different countries have different microepidemics, with very different levels of transmission and risk groups, changing over time. Therefore, focus should be on high-transmission geographies, people at highest risk for HIV, and the package of interventions that are most likely to have the largest effect in each different microepidemic. Building on the backbone of behaviour change, condom use, and medical male circumcision, as well as expanded use of antiretroviral drugs for infected people and pre-exposure prophylaxis for uninfected people at high risk of infection, it is now possible to consider the prospect of what would be one of the most remarkable achievements in the history of public health: reduction of HIV transmission from a pandemic to low-level endemicity.

Incarceration is associated with used syringe lending among active injection drug users with detectable plasma HIV-1 RNA: a longitudinal analysis

Background

Informed by recent studies demonstrating the central role of plasma HIV-1 RNA viral load (VL) on HIV transmission, interventions to employ HIV antiretroviral treatment as prevention (TasP) are underway. To optimize these efforts, evidence is needed to identify factors associated with both non-suppressed VL and HIV risk behaviours. Thus, we sought to assess the possible role played by exposure to correctional facilities on VL non-suppression and used syringe lending among HIV-seropositive people who use injection drugs (PWID).

Methods

We used data from the ACCESS study, a community-recruited prospective cohort. We used longitudinal multivariate mixed-effects analyses to estimate the relationship between incarceration and plasma HIV-1 RNA > 500 copies/mL among antiretroviral therapy (ART)-exposed active PWID and, during periods of non-suppression, the relationship between incarceration and used syringe lending.

Results

Between May 1996 and March 2012, 657 ART-exposed PWID were recruited. Incarceration was independently associated with higher odds of VL non-suppression (Adjusted Odds Ratio [AOR] = 1.54, 95% Confidence Interval [95% CI]: 1.10, 2.16). In a separate multivariate model restricted to periods of VL non-suppression, incarceration was independently associated with lending used syringes (AOR = 1.81, 95% CI: 1.03, 3.18).

Conclusions

The current findings demonstrate that incarceration is associated with used syringe lending among active PWID with detectable plasma HIV-1 RNA. Our results provide a possible pathway for the commonly observed association between incarceration and increased risk of HIV transmission. Our results suggest that alternatives to incarceration of non-violent PWID and evidence-based combination HIV prevention interventions for PWID within correctional facilities are urgently needed.

Sexual behaviour in a rural high HIV prevalence South African community: time trends in the antiretroviral treatment era

Objectives:

Data from generalized epidemic settings have consistently found that patients on antiretroviral therapy (ART) reduce sexual risk behaviours, but how sexual behaviour changes in the general population in response to ART availability, including amongst HIV-uninfected and undiagnosed adults, has not been characterized in these settings.

Design:

General population open cohort.

Methods:

We report trends in sexual behaviour indicators for men aged 17–54 years and women aged 17–49 years in rural KwaZulu-Natal province, based on annual sexual behaviour surveys during ART scale-up from 2005 to 2011. Estimates are adjusted for survey nonparticipation and nonresponse to individual survey items using inverse probability weighting and multiple imputation. Trends are presented by HIV status, knowledge of status, age and marital status.

Results:

Reports of condom use at last sex with a regular partner increased by 2.6% points per year [95% confidence interval (CI) 1.5%, 3.7%] for men and 4.1% per year (3.0%, 5.3%) for women. Condom use at last sex with a casual partner was high and did not change significantly over the period for both sexes. There were statistically significant declines in the percentage reporting multiple partnerships in the last year and the point prevalence of concurrency. Trends within subgroups were generally consistent with overall estimates.

Conclusion:

We find no evidence of increased sexual risk-taking following ART availability and protective changes in some behaviours, suggesting that general trends in sexual behaviour are not counter-acting preventive effects of HIV treatment. Continued monitoring of population-level sexual behaviour indicators will be essential to interpret the success of combination-prevention programmes.

Novel directions in HIV-1 vaccines revealed from clinical trials

PURPOSE OF REVIEW

Considerable HIV-1 vaccine development efforts have been deployed over the past decade. Put into perspective, the results from efficacy trials and the identification of correlates of risk have opened large and unforeseen avenues for vaccine development.

RECENT FINDINGS

The Thai efficacy trial, RV144, provided the first evidence that HIV-1 vaccine protection against HIV-1 acquisition could be achieved. The correlate of risk analysis showed that IgG antibodies against the gp120 V2 loop inversely correlated with a decreased risk of infection, whereas Env-specific IgA directly correlated with risk. Further clinical trials will focus on testing new envelope subunit proteins formulated with adjuvants capable of inducing higher and more durable functional antibody responses (both binding and broadly neutralizing antibodies). Moreover, vector-based vaccine regimens that can induce cell-mediated immune responses in addition to humoral responses remain a priority.

SUMMARY

Future efficacy trials will focus on prevention of HIV-1 transmission in heterosexual population in Africa and MSM in Asia. The recent successes leading to novel directions in HIV-1 vaccine development are a result of collaboration and commitment among vaccine manufacturers, funders, scientists and civil society stakeholders. Sustained and broad collaborative efforts are required to advance new vaccine strategies for higher levels of efficacy.

Can combination prevention strategies reduce HIV transmission in generalized epidemic settings in Africa? The HPTN 071 (PopART) study plan in South Africa and Zambia

The HIV Prevention Trials Network (HPTN) is conducting the HPTN 071 (PopART) study in 21 communities in Zambia and South Africa with support from a consortium of funders. HPTN 071 (PopART) is a community-randomized trial of a combination prevention strategy to reduce HIV incidence in the context of the generalized epidemic of southern Africa. The full PopART intervention strategy is anchored in home-based HIV testing and facilitated linkage of HIV-infected persons to care through community health workers and universal antiretroviral therapy for seropositive persons regardless of CD4+ cell count or HIV viral load. To further reduce the risk of HIV acquisition among uninfected individuals, the study aims to expand voluntary medical male circumcision, diagnosis and treatment of sexually transmitted infections, behavioral counseling, and condom distribution. The full PopART intervention strategy also incorporates promotion of other interventions designed to reduce HIV and tuberculosis transmission, including optimization of the prevention of mother-to-child HIV transmission and enhanced individual and public health tuberculosis services. Success for the PopART strategy depends on the ability to increase coverage for the study interventions whose uptake is a necessary antecedent to a prevention effect. Processes will be measured to assess the degree of penetration of the interventions into the communities. A randomly sampled population cohort from each community will be used to measure the impact of the PopART strategy on HIV incidence over 3 years. We describe the strategy being tested and progress to date in the HPTN 071 (PopART) study.

An HIV Vaccine for South-East Asia-Opportunities and Challenges

Recent advances in HIV vaccine development along with a better understanding of the immune correlates of risk have emerged from the RV144 efficacy trial conducted in Thailand. Epidemiological data suggest that CRF01_AE is still predominant in South-East Asia and is spreading in China with a growing number of circulating recombinant forms due to increasing human contact, particularly in large urban centers, tourist locations and in sites of common infrastructure. A vaccine countering CRF01_AE is a priority for the region. An Asia HIV vaccine against expanding B/E or BCE recombinant forms should be actively pursued. A major challenge that remains is the conduct of efficacy trials in heterosexual populations in this region. Men who have sex with men represent the main target population for future efficacy trials in Asia. Coupling HIV vaccines with other prevention modalities in efficacy trials might also be envisaged. These new avenues will only be made possible through the conduct of large-scale efficacy trials, interdisciplinary teams, international collaborations, and strong political and community commitments.

Combination prevention: new hope for stopping the epidemic

HIV research has identified approaches that can be combined to be more effective in transmission reduction than any 1 modality alone: delayed adolescent sexual debut, mutual monogamy or sexual partner reduction, correct and consistent condom use, pre-exposure prophylaxis with oral antiretroviral drugs or vaginal microbicides, voluntary medical male circumcision, antiretroviral therapy (ART) for prevention (including prevention of mother to child HIV transmission [PMTCT]), treatment of sexually transmitted infections, use of clean needles for all injections, blood screening prior to donation, a future HIV prime/boost vaccine, and the female condom. The extent to which evidence-based modalities can be combined to prevent substantial HIV transmission is largely unknown, but combination approaches that are truly implementable in field conditions are likely to be far more effective than single interventions alone. Analogous to PMTCT, "treatment as prevention" for adult-to-adult transmission reduction includes expanded HIV testing, linkage to care, antiretroviral coverage, retention in care, adherence to therapy, and management of key co-morbidities such as depression and substance use. With successful viral suppression, persons with HIV are far less infectious to others, as we see in the fields of sexually transmitted infection control and mycobacterial disease control (tuberculosis and leprosy). Combination approaches are complex, may involve high program costs, and require substantial global commitments. We present a rationale for such investments and cite an ongoing research agenda that seeks to determine how feasible and cost-effective a combination prevention approach would be in a variety of epidemic contexts, notably that in a sub-Saharan Africa.

Assessing priorities for combination HIV prevention research for men who have sex with men (MSM) in Africa

A consultation was hosted in South Africa (March 2011) to assess the combination HIV prevention research priorities of academics, implementers and MSM community leaders. Sixty-nine participants, representing 17 African countries, participated. Interactive strategies were used to present current data on HIV interventions and discussions on research possibilities were facilitated with research priorities identified using the nominal group technique. Data were analysed using directed content analysis. Health worker training, social mobilisation, and community engagement were prioritised as structural interventions. Comprehensive counselling was identified as the most important behavioural intervention, with adherence, mental health, and risk reduction counselling identified as key counselling topics. Rectal microbicides, oral pre-exposure prophylaxis and condom and lubricant distribution were the most important biomedical interventions. This consultation resulted in the first combination HIV prevention research agenda for MSM in Africa. Outcomes will inform future research and be used to advocate for combination approaches to HIV prevention for MSM.

North-South Corridor Demonstration Project: Ethical and Logistical Challenges in the Design of a Demonstration Study of Early Antiretroviral Treatment for Long Distance Truck Drivers along a Transport Corridor through South Africa, Zimbabwe, and Zambia

Background. Long-distance truck drivers are at risk of acquiring and transmitting HIV and have suboptimal access to care. New HIV prevention strategies using antiretroviral drugs to reduce transmission risk (early antiretroviral therapy (ART) at CD4 count >350 cells/μL) have shown efficacy in clinical trials. Demonstration projects are needed to evaluate “real world” programme effectiveness. We present the protocol for a demonstration study to evaluate the feasibility, acceptability, and cost of an early ART intervention for HIV-positive truck drivers along a transport corridor across South Africa, Zimbabwe, and Zambia, as part of an enhanced strategy to improve treatment adherence and retention in care. Methods and Analysis. This demonstration study would follow an observational cohort of truck drivers receiving early treatment. Our mixed methods approach includes quantitative, qualitative, and economic analyses. Key ethical and logistical issues are discussed (i.e., choice of drug regimen, recruitment of participants, and monitoring of adherence, behavioural changes, and adverse events). Conclusion. Questions specific to the design of tailored early ART programmes are amenable to operational research approaches but present substantial ethical and logistical challenges. Addressing these in demonstration projects can inform policy decisions regarding strategies to reduce health inequalities in access to HIV prevention and treatment programmes.

Understanding the potential impact of a combination HIV prevention intervention in a hyper-endemic community

OBJECTIVES

Despite demonstrating only partial efficacy in preventing new infections, available HIV prevention interventions could offer a powerful strategy when combined. In anticipation of combination HIV prevention programs and research studies we estimated the population-level impact of combining effective scalable interventions at high population coverage, determined the factors that influence this impact, and estimated the synergy between the components.

METHODS

We used a mathematical model to investigate the effect on HIV incidence of a combination HIV prevention intervention comprised of high coverage of HIV testing and counselling, risk reduction following HIV diagnosis, male circumcision for HIV-uninfected men, and antiretroviral therapy (ART) for HIV-infected persons. The model was calibrated to data for KwaZulu-Natal, South Africa, where adult HIV prevalence is approximately 23%.

RESULTS

Compared to current levels of HIV testing, circumcision, and ART, the combined intervention with ART initiation according to current guidelines could reduce HIV incidence by 47%, from 2.3 new infections per 100 person-years (pyar) to 1.2 per 100 pyar within 4 years and by almost 60%, to 1 per 100 pyar, after 25 years. Short-term impact is driven primarily by uptake of testing and reductions in risk behaviour following testing while long-term effects are driven by periodic HIV testing and retention in ART programs. If the combination prevention program incorporated HIV treatment upon diagnosis, incidence could be reduced by 63% after 4 years and by 76% (to about 0.5 per 100 pyar) after 15 years. The full impact of the combination interventions accrues over 10-15 years. Synergy is demonstrated between the intervention components.

CONCLUSION

High coverage combination of evidence-based strategies could generate substantial reductions in population HIV incidence in an African generalized HIV epidemic setting. The full impact could be underestimated by the short assessment duration of typical evaluations.

Combination implementation for HIV prevention: moving from clinical trial evidence to population-level effects

The promise of combination HIV prevention-the application of multiple HIV prevention interventions to maximise population-level effects-has never been greater. However, to succeed in achieving significant reductions in HIV incidence, an additional concept needs to be considered: combination implementation. Combination implementation for HIV prevention is the pragmatic, localised application of evidence-based strategies to enable high sustained uptake and quality of interventions for prevention of HIV. In this Review, we explore diverse implementation strategies including HIV testing and counselling models, task shifting, linkage to and retention in care, antiretroviral therapy support, behaviour change, demand creation, and structural interventions, and discusses how they could be used to complement HIV prevention efforts such as medical male circumcision and treatment as prevention. HIV prevention and treatment have arrived at a pivotal moment when combination efforts might result in substantial enough population-level effects to reverse the epidemic and drive towards elimination of HIV. Only through careful consideration of how to implement and operationalise HIV prevention interventions will the HIV community be able to move from clinical trial evidence to population-level effects.

An assessment of the likely acceptability of vaginal microbicides for HIV prevention among women in rural Ghana

BACKGROUND

The findings of the CAPRISA tenofovir studies have raised expectations that soon an approved microbicide would be available. However it is in only a limited number of countries in sub-Saharan Africa that the acceptability of microbicides has been evaluated. We conducted a study to assess the acceptability of vaginal microbicides among women in rural Ghana.

METHODS

The study employs a mixed method design, using cross-sectional survey and focus group discussions to further understand issues related to awareness and attitudes towards microbicide development, acceptability and perceived partner attitudes among pregnant women attending antenatal clinic in two health facilities in the Kintampo North municipality of Ghana. We used logistic regression to identify possible predictors of microbicide acceptability among the women surveyed.

RESULTS

Although only 2% of the 504 women were aware of the development of microbicides, 95% were willing to use one when it became available. The cost of a microbicide that will be considered affordable to 50% of women was US$0.75. Although there were concerns about possible wetting effect, gel or creams were the most preferred (68% of women) formulation. Although 71% thought their partners will find microbicide acceptable, apprehensions about the feasibility of and consequences of failed discreet use were evident. 49% of women were concerned about possible negative effect of microbicide on sexual pleasure. Perceived partner acceptability (O.R. =17.7; 95%C.I. 5.03-62.5) and possibility of discreet use (O.R. =8.9 95%C.I. 2.63-30.13) were the important predictors of microbicide acceptability.

CONCLUSION

Achieving microbicide acceptability among male partners should be made a part of the promotive interventions for ensuring effective use among women in rural Ghana.

The future of HIV prevention

In the decades since the emergence of HIV, numerous approaches to prevent transmission have been tested with varying degrees of success. Because a highly effective vaccine will not be available within the next decade, it is increasingly clear that preventing new HIV infections will require successful implementation of promising behavioral and biomedical interventions in combination. These prevention packages must be sufficiently flexible to include a variety of evidence-based interventions that serve each dynamic population they target, particularly those who are most vulnerable. To optimize the impact of combination intervention packages, well-designed implementation science studies are vital. Efficacy in a clinical trial does not necessarily translate to effectiveness at the population-level, and prioritized research studies should investigate programmatic implementation and operations scale-up and new methods to monitor and evaluate these processes both for organization and cost-effectiveness. With an estimated 2.7 million people becoming newly infected with HIV in 2010, the prevention of HIV remains an urgent global health priority. Since the emergence of HIV/AIDS more than 30 years ago, the evidence base for HIV prevention has expanded and evolved. Here we explore the status of evidence-based HIV prevention, describing both the continuing challenges and the emerging opportunities to reduce HIV incidence.

Successes and challenges of HIV prevention in men who have sex with men

Men who have sex with men (MSM) have been substantially affected by HIV epidemics worldwide. Epidemics in MSM are re-emerging in many high-income countries and gaining greater recognition in many low-income and middle-income countries. Better HIV prevention strategies are urgently needed. Our review of HIV prevention strategies for MSM identified several important themes. At the beginning of the epidemic, stand-alone behavioural interventions mostly aimed to reduce unprotected anal intercourse, which, although somewhat efficacious, did not reduce HIV transmission. Biomedical prevention strategies reduce the incidence of HIV infection. Delivery of barrier and biomedical interventions with coordinated behavioural and structural strategies could optimise the effectiveness of prevention. Modelling suggests that, with sufficient coverage, available interventions are sufficient to avert at least a quarter of new HIV infections in MSM in diverse countries. Scale-up of HIV prevention programmes for MSM is difficult because of homophobia and bias, suboptimum access to HIV testing and care, and financial constraints.

The Surprising Role of Amyloid Fibrils in HIV Infection

Despite its discovery over 30 years ago, human immunodeficiency virus (HIV) continues to threaten public health worldwide. Semen is the principal vehicle for the transmission of this retrovirus and several endogenous peptides in semen, including fragments of prostatic acid phosphatase (PAP248-286 and PAP85-120) and semenogelins (SEM1 and SEM2), assemble into amyloid fibrils that promote HIV infection. For example, PAP248-286 fibrils, termed SEVI (Semen derived Enhancer of Viral Infection), potentiate HIV infection by up to 105-fold. Fibrils enhance infectivity by facilitating virion attachment and fusion to target cells, whereas soluble peptides have no effect. Importantly, the stimulatory effect is greatest at low viral titers, which mimics mucosal transmission of HIV, where relatively few virions traverse the mucosal barrier. Devising a method to rapidly reverse fibril formation (rather than simply inhibit it) would provide an innovative and urgently needed preventative strategy for reducing HIV infection via the sexual route. Targeting a host-encoded protein conformer represents a departure from traditional microbicidal approaches that target the viral machinery, and could synergize with direct antiviral approaches. Here, we review the identification of these amyloidogenic peptides, their mechanism of action, and various strategies for inhibiting their HIV-enhancing effects.

Views of policymakers, healthcare workers and NGOs on HIV pre-exposure prophylaxis (PrEP): a multinational qualitative study

OBJECTIVES

To examine policymakers and providers' views on pre-exposure prophylaxis (PrEP) and their willingness to support its introduction, to inform policy and practice in this emerging field.

DESIGN

Semistructured qualitative interview study.

SETTING

Peru, Ukraine, India, Kenya, Uganda, Botswana and South Africa.

PARTICIPANTS

35 policymakers, 35 healthcare workers and 21 non-governmental organisation representatives involved in HIV prevention.

RESULTS

Six themes emerged from the data: (1) perceived HIV prevention landscape: prevention initiatives needed to be improved and expanded; (2) PrEP awareness: 50 of 91 participants had heard of PrEP; (3) benefits of PrEP: one component of the combination prevention arsenal that could help prioritise HIV prevention, empower key populations and result in economic gains; (4) challenges of PrEP: regimen complexity, cost and cost-effectiveness, risk compensation, efficacy and effectiveness, stigmatisation and criminalisation, information and training and healthcare system capacity; (5) programmatic considerations: user eligibility, communication strategy, cost, distribution, medication and HIV testing compliance and (6) early versus late implementation: participants were divided as to whether they would support an early introduction of PrEP in their country or would prefer to wait until it has been successfully implemented in other countries, with around half of those we spoke to supporting each option. Very few said they would not support PrEP at all.

CONCLUSIONS

Despite the multiple challenges identified, there was general willingness to support the introduction of PrEP. Yet, strengthening existing HIV prevention efforts was also deemed necessary. Our results suggest that an effective PrEP programme would be delivered in healthcare facilities and involve non-governmental organisations and the community and consider the needs of mobile populations. Comprehensive information packages and training for users and providers would be critical. The cost of PrEP would be affordable and possibly segmented. Extensive counselling and innovative monitoring measures ought to be considered.

Antiretroviral therapy in prevention of HIV and TB: update on current research efforts

There is considerable scientific evidence supporting the use of antiretroviral therapy (ART) in prevention of human immunodeficiency virus (HIV) and tuberculosis (TB) infections. The complex nature of the HIV and TB prevention responses, resource constraints, remaining questions about cost and feasibility, and the need to use a solid evidence base to make policy decisions, and the implementation challenges to translating trial data to operational settings require a well-organised and coordinated response to research in this area. To this end, we aimed to catalogue the ongoing and planned research activities that evaluate the impact of ART plus other interventions on HIV- and/or TB-related morbidity, mortality, risk behaviour, HIV incidence and transmission. Using a limited search methodology, 50 projects were identified examining ART as prevention, representing 5 regions and 52 countries with a global distribution. There are 24 randomised controlled clinical trials with at least 12 large randomised individual or community cluster trials in resource-constrained settings that are in the planning or early implementation stages. There is considerable heterogeneity between studies in terms of methodology, interventions and geographical location. While the identified studies will undoubtedly advance our understanding of the efficacy and effectiveness of ART for prevention, some key questions may remain unanswered or only partially answered. The large number and wide variety of research projects emphasise the importance of this research issue and clearly demonstrate the potential for synergies, partnerships and coordination across funding agencies.

HIV prevention transformed: the new prevention research agenda

We have entered a new era in HIV prevention whereby priorities have expanded from biomedical discovery to include implementation, effectiveness, and the effect of combination prevention at the population level. However, gaps in knowledge and implementation challenges remain. In this Review we analyse trends in the rapidly changing landscape of HIV prevention, and chart a new path for HIV prevention research that focuses on the implementation of effective and efficient combination prevention strategies to turn the tide on the HIV pandemic.