Examining the promise of HIV elimination by 'test and treat' in hyperendemic settings

Rapid HIV self-testing: long in coming but opportunities beckon

The recent approval by the United States Food and Drug Administration of a rapid HIV self-test marks a significant milestone in the evolution of HIV testing approaches. With nearly one in five people living with HIV in the United States still undiagnosed and an even higher proportion unaware of their infection globally, this decision reflects a new willingness to offer diverse options to get tested for HIV. Rapid self-testing offers several distinct opportunities to improve testing among those with undiagnosed HIV: to encourage testing among those who might not otherwise be tested, to increase the frequency of testing among persons at highest risk for new infection, and to facilitate mutual HIV testing with sex partners. To date, the path to regulatory approval has been long but instructive. The studies and clinical trials required for regulatory approval in the United States provide insight into the performance and potential implications of HIV self-tests as they become available for sale directly to consumers. Although some persistent reservations about self-testing for HIV remain, including the 'window period' of the current test kit, its cost, and its effectiveness for facilitating entry to medical care, others have been dispelled. Self-testing in resource-constrained settings is also promising, including self-testing of health professionals. At present, although the impact has yet to be determined, availability of this new option might offer potential opportunities to improve HIV diagnosis and facilitate both treatment and prevention.

Should home-based HIV testing and counseling services be offered periodically in programs of ARV treatment as prevention? A case study in Likoma (Malawi)

To reduce HIV incidence, prevention programs centered on the use of antiretrovirals require scaling-up HIV testing and counseling (HTC). Home-based HTC services (HBHTC) increase HTC coverage, but HBHTC has only been evaluated during one-off campaigns. Two years after an initial HBHTC campaign ("round 1"), we conducted another HBHTC campaign ("round 2") in Likoma (Malawi). HBHTC participation increased during round 2 among women (from 74 to 83%, P < 0.01). New HBHTC clients were recruited, especially at ages 25 and older. Only 6.9% of women but 15.9% of men remained unreached by HBHTC after round 2. HIV prevalence during round 2 was low among clients who were HIV-negative during round 1 (0.7%), but high among women who received their first ever HIV test during round 2 (42.8%). The costs per newly diagnosed infection increased significantly during round 2. Periodically conducting HBHTC campaigns can further increase HTC, but supplementary interventions to enroll individuals not reached by HBHTC are needed.

Failure to test for HIV in rural Ethiopia: knowledge and belief correlates and implications for universal test and treat strategies

Goals of universal "test and treat" will never be fully realized if testing acceptance remains low, including rural areas, where HIV is increasingly recognized. We surveyed 250 randomly selected households from a rural Ethiopian town (Arba Minch) and surrounding villages about HIV testing experience, knowledge, and attitudes. Of the 558 adults, 45% were never HIV tested. Those never tested for HIV were more likely to be (P < .05) ≥45 years, rural villagers, and unaware of the benefits of antiretroviral therapy treatment and that persons with HIV can appear healthy; they were more likely to believe HIV-infected persons would be stigmatized and unsupported by their communities. Of those never tested, 70% were interested in HIV testing if offered. Despite recommendations that all persons be HIV tested, almost half of the adult residents in this rural community were never tested. Programs to increase HIV testing must include measures to address stigma/discrimination and knowledge deficits including benefits of early diagnosis and treatment.

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.

Clinical uncertainties, health service challenges, and ethical complexities of HIV "test-and-treat": a systematic review

Despite the HIV "test-and-treat" strategy's promise, questions about its clinical rationale, operational feasibility, and ethical appropriateness have led to vigorous debate in the global HIV community. We performed a systematic review of the literature published between January 2009 and May 2012 using PubMed, SCOPUS, Global Health, Web of Science, BIOSIS, Cochrane CENTRAL, EBSCO Africa-Wide Information, and EBSCO CINAHL Plus databases to summarize clinical uncertainties, health service challenges, and ethical complexities that may affect the test-and-treat strategy's success. A thoughtful approach to research and implementation to address clinical and health service questions and meaningful community engagement regarding ethical complexities may bring us closer to safe, feasible, and effective test-and-treat implementation.

Test-and-treat in Los Angeles: a mathematical model of the effects of test-and-treat for the population of men who have sex with men in Los Angeles County

BACKGROUND

There is evidence to suggest that antiretroviral therapy (ART) and testing for human immunodeficiency virus (HIV) reduce the probability of transmission of HIV. This has led health officials across the United States to take steps toward a test-and-treat policy. However, the extent of the benefits generated by test-and-treat is debatable, and there are concerns, such as increased multidrug resistance (MDR), that remain unaddressed.

METHODS

We developed a deterministic epidemiologic model to simulate the HIV/AIDS epidemic for men who have sex with men (MSM) in Los Angeles County (LAC). We calibrated the model to match the HIV surveillance data from LAC across a 10-year period, starting in 2000. We then modified our model to simulate the test-and-treat policy and compared epidemiologic outcomes under the test-and-treat scenario to the status quo scenario over the years 2012-2023. Outcome measures included new infections, deaths, new AIDS cases, and MDR.

RESULTS

Relative to the status quo, the test-and-treat model resulted in a 34% reduction in new infections, 19% reduction in deaths, and 39% reduction in new AIDS cases by 2023. However, these results are counterbalanced by a near doubling of the prevalence of MDR (9.06% compared to 4.79%) in 2023. We also found that the effects of increasing testing and treatment were not complementary.

CONCLUSIONS

Although test-and-treat generates substantial benefits, it will not eliminate the epidemic for MSM in LAC. Moreover, these benefits are counterbalanced by large increases in MDR.

Controlling the HIV Epidemic with Antiretrovirals

In the context of emerging evidence related to preexposure prophylaxis and HIV treatment as prevention, an evidence summit was held in mid-2012 to discuss the current state of the science and to provide a platform for consensus building around whether and how these prevention strategies might be implemented globally. Health care providers, researchers, policy makers, people living with HIV/AIDS, and representatives of government authorities, donor agencies, pharmaceutical companies, advocacy organizations, and professional associations attended from 52 countries. An international advisory committee was convened to identify key messages and recommendations based upon the data presented and discussed at the summit. The advisory committee further worked to develop this consensus statement meant to assist relevant stakeholders in taking stock and mapping out a route forward to enhance the HIV prevention armamentarium.

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.

Clinician practices and attitudes regarding early antiretroviral therapy in the United States

BACKGROUND

Use of antiretroviral therapy (ART) to prevent HIV transmission has received substantial attention after a recent trial demonstrating efficacy of ART to reduce HIV transmission in HIV-discordant couples.

OBJECTIVE

To assess practices and attitudes of HIV clinicians regarding early initiation of ART for treatment and prevention of HIV at sites participating in the HIV Prevention Trials Network 065 study.

DESIGN

Cross-sectional internet-based survey.

METHODS

: ART-prescribing clinicians (n = 165 physicians, nurse practitioners, physician assistants) at 38 HIV care sites in Bronx, NY, and Washington, DC, completed a brief anonymous Internet survey, before any participation in the HIV Prevention Trials Network 065 study. Analyses included associations between clinician characteristics and willingness to prescribe ART for prevention.

RESULTS

: Almost all respondents (95%), of whom 59% were female, 66% white, and 77% HIV specialists, "strongly agreed/agreed" that early ART can decrease HIV transmission. Fifty-six percent currently recommend ART initiation for HIV-infected patients with CD4+ count <500 cells per cubic millimeter, and 14% indicated that they initiate ART irrespective of CD4+ count. Most (75%) indicated that they would consider initiating ART earlier than otherwise indicated for patients in HIV-discordant sexual partnerships, and 40% would do so if a patient was having unprotected sex with a partner of unknown HIV status. There were no significant differences by age, gender, or clinician type in likelihood of initiating ART for reasons including HIV transmission prevention to sexual partners.

CONCLUSIONS

This sample of US clinicians indicated support for early ART initiation to prevent HIV transmission, especially for situations where such transmission would be more likely to occur.

Adaptation of a U.S. evidence-based Positive Prevention intervention for youth living with HIV/AIDS in Kinshasa, Democratic Republic of the Congo

Effective HIV prevention programs for people living with HIV/AIDS (PLWH) are important to reduce new infections and to ensure PLWH remain healthy. This paper describes the systematic adaptation of a U.S.-developed Evidence Based Intervention (EBI) using the Centers for Disease Control and Prevention (CDC) Map of Adaption Process for use at a Pediatric Hospital in Kinshasa, Democratic Republic of the Congo (DRC). The adapted intervention, Supporting Youth and Motivating Positive Action or SYMPA, a six-session risk reduction intervention targeted for youth living with HIV/AIDS (YLWH) in Kinshasa was adapted from the Healthy Living Project and guided by the Social Action Theory. This paper describes the process of implementing the first four steps of the ADAPT framework (Assess, Select, Prepare, and Pilot). Our study has shown that an EBI developed and implemented in the U.S. can be adapted successfully for a different target population in a low-resource context through an iterative process following the CDC ADAPT framework. This process included reviewing existing literature, adapting and adding components, and focusing on increasing staff capacity. This paper provides a rare, detailed description of the adaptation process and may aid organizations seeking to adapt and implement HIV prevention EBIs in sub-Saharan Africa and beyond.

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.

Barriers to Provider-Delivered Sexual Behavior Counseling for Youth Living with HIV/AIDS in the Democratic Republic of the Congo

AIMS

The study aimed to understand providers' role in delivering HIV transmission prevention counseling to youth living with HIV (YLWH).

METHODS

We conducted 14 in-depth interviews with providers in Kinshasa, DRC.

RESULTS

Providers' lack of knowledge and comfort in talking to youth about sex because of cultural and religious beliefs about sexuality, coupled with confusion about legal issues related to youth and contraception, made it difficult for them to effectively counsel youth.

IMPLICATIONS FOR PRACTICE AND POLICY

In order for providers to deliver effective prevention counseling to YLWH, clinics should follow adolescent-friendly clinic standards, provide counseling in an adolescent-friendly style, and institute an effective referral system for additional prevention services.

CONCLUSION

HIV prevention services can be improved through the creation of an adolescent-friendly environment and by providing "values clarification" and skill-based trainings so that providers are able to assess the role of their own beliefs and learn new skills.

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.

Predictors of late presentation for HIV diagnosis: a literature review and suggested way forward

Early commencement of antiretroviral treatment can be beneficial and economical in the long run. Despite global advances in access to care, a significant proportion of adults presenting at HIV/AIDS care facilities present with advanced HIV disease. Understanding factors associated with late presentation for HIV/AIDS services is critical to the development of effective programs and treatment strategies. Literature on factors associated with late presentation for an HIV diagnosis is reviewed. Highlighted is the current emphasis on socio-demographic factors, the limited exploration of psychosocial correlates, and inconsistencies in the definition of late presentation that make it difficult to compare findings across different studies. Perspectives based on experiences from resource limited settings are underreported. Greater exploration of psychosocial predictors of late HIV diagnosis is advocated for, to guide future intervention research and to inform public policy and practice targeted at 'difficult to reach' populations.

Antiretroviral-based HIV-1 prevention: antiretroviral treatment and pre-exposure prophylaxis

Antiretroviral-based HIV-1 prevention strategies - including antiretroviral treatment (ART) to reduce the infectiousness of individuals with HIV-1 and oral and topical pre-exposure prophylaxis (PrEP) for uninfected individuals to prevent HIV-1 acquisition - are the most promising new approaches for decreasing HIV-1 spread. Observational studies among HIV-1 serodiscordant couples have associated ART initiation with a reduction in HIV-1 transmission risk of 80-92%, and a recent randomized trial demonstrated that earlier initiation of ART (that is, at CD4(+) T-cell counts between 350 and 550 cells/mm(3)), in the context of virological monitoring and adherence support, resulted in a 96% reduction in HIV-1 transmission. A number of ongoing and recently-completed clinical trials have assessed the efficacy of PrEP for HIV-1 prevention as pericoitally administered or daily-administered 1% tenofovir gel and daily oral tenofovir disoproxil fumarate (TDF) and combination emtricitabine (FTC)/TDF. Completed studies have demonstrated HIV-1 protection efficacies ranging from 39% to 75%. However, two trials in African women have shown no HIV-1 protection with TDF and FTC/TDF PrEP; the reasons for lack of efficacy in those trials are being investigated. Adherence is likely the key to efficacy of antiretrovirals for HIV-1 prevention, both as ART and PrEP. Critical unanswered questions for successful delivery of antiretroviral-based HIV-1 prevention include how to target ART and PrEP to realize maximum population benefits, whether HIV-1-infected individuals at earlier stages of infection would accept ART to reduce their risk for transmitting HIV-1 and whether highest-risk HIV-1-negative persons would use PrEP, and whether high adherence could be sustained to achieve high effectiveness.

Using plasma viral load to guide antiretroviral therapy initiation to prevent HIV-1 transmission

BACKGROUND

Current WHO guidelines recommend antiretroviral therapy (ART) initiation at CD4 counts ≤350 cells/µL. Increasing this threshold has been proposed, with a primary goal of reducing HIV-1 infectiousness. Because the quantity of HIV-1 in plasma is the primary predictor of HIV-1 transmission, consideration of plasma viral load in ART initiation guidelines is warranted.

METHODS

Using per-sex-act infectivity estimates and cross-sectional sexual behavior data from 2,484 HIV-1 infected persons with CD4 counts >350 enrolled in a study of African heterosexual HIV-1 serodiscordant couples, we calculated the number of transmissions expected and the number potentially averted under selected scenarios for ART initiation: i) CD4 count <500 cells/µL, ii) viral load ≥10,000 or ≥50,000 copies/mL and iii) universal treatment. For each scenario, we estimated the proportion of expected infections that could be averted, the proportion of infected persons initiating treatment, and the ratio of these proportions.

RESULTS

Initiating treatment at viral load ≥50,000 copies/mL would require treating 19.8% of infected persons with CD4 counts >350 while averting 40.5% of expected transmissions (ratio 2.0); treating at viral load ≥10,0000 copies/mL had a ratio of 1.5. In contrast, initiation at CD4 count <500 would require treating 41.8%, while averting 48.4% (ratio 1.1).

CONCLUSION

Inclusion of viral load in ART initiation guidelines could permit targeting ART resources to HIV-1 infected persons who have a higher risk of transmitting HIV-1. Further work is needed to estimate costs and feasibility.

Nested model reveals potential amplification of an HIV epidemic due to drug resistance

The use of antiretroviral therapy (ART) is the most efficient measure in controlling the HIV epidemic. However, emergence of drug-resistant strains can reduce the potential benefits of ART. The viral dynamics of drug-sensitive and drug-resistant strains at the individual level may play a crucial role in the emergence and spread of drug resistance in a population. We investigate the effect of the viral dynamics within an infected individual on the epidemiological dynamics of HIV using a nested model that links both dynamical levels. A time-dependent between-host transmission rate that receives feedback from a model of two-strain virus dynamics within a host is incorporated into an epidemiological model of HIV. We analyze the resulting dynamics of the model and identify model parameters such as time when ART is initiated, fraction of cases treated, and the probability that a patient develops drug resistance, as having the greatest impact on total infection and prevalence of drug resistance. Importantly, for small values of the risk of a patient developing drug resistance, increasing the fraction of cases treated can increase the cumulative number of infected individuals. Such a pattern is the result of the balance between not treating a patient and having future cases still sensitive to treatment, and treating the patient and increasing the chances for future (untreatable) drug-resistant infections. The current modeling framework incorporates important aspects of virus dynamics within a host into an epidemic model. This approach provides useful insights on the drug resistance dynamics of an epidemic of HIV, which may assist in identifying an optimal use of ART.

Human resources needs for universal access to antiretroviral therapy in South Africa: a time and motion study

BACKGROUND

Although access to life-saving treatment for patients infected with HIV in South Africa has improved substantially since 2004, treating all eligible patients (universal access) remains elusive. As the prices of antiretroviral drugs have dropped over the past years, availability of human resources may now be the most important barrier to achieving universal access to HIV treatment in Africa. We quantify the number of HIV health workers (HHWs) required to be added to the current HIV workforce to achieve universal access to HIV treatment in South Africa, under different eligibility criteria.

METHODS

We performed a time and motion study in three HIV clinics in a rural, primary care-based HIV treatment program in KwaZulu-Natal, South Africa, to estimate the average time per patient visit for doctors, nurses, and counselors. We estimated the additional number of HHWs needed to achieve universal access to HIV treatment within one year.

RESULTS

For universal access to HIV treatment for all patients with a CD4 cell count of ≤350 cells/μl, an additional 2,200 nurses, 3,800 counselors, and 300 doctors would be required, at additional annual salary cost of 929 million South African rand (ZAR), equivalent to US$ 141 million. For universal treatment ('treatment as prevention'), an additional 6,000 nurses, 11,000 counselors, and 800 doctors would be required, at an additional annual salary cost of ZAR 2.6 billion (US$ 400 million).

CONCLUSIONS

Universal access to HIV treatment for patients with a CD4 cell count of ≤350 cells/μl in South Africa may be affordable, but the number of HHWs available for HIV treatment will need to be substantially increased. Treatment as prevention strategies will require considerable additional financial and human resources commitments.

The prevalence and correlates of receiving confirmatory HIV test results among newly diagnosed HIV-positive individuals at a community-based testing center

This study examined the prevalence and correlates of completing the HIV testing process-specifically receiving a confirmatory HIV test and returning for the results-in a sample of newly diagnosed HIV-positive individuals at an HIV testing center in New York City. Of the 213 individuals who received a reactive rapid HIV test result, 82% received a confirmatory HIV test. Of the 236 individuals who received a positive result on a rapid or traditional HIV test that was validated by a positive confirmatory HIV test, 65% returned for the confirmatory test results. Multivariate analyses revealed that being a non-U.S. citizen, homeless/living in transitional housing, being uninsured, and testing off-site were significantly associated with completing the HIV testing process. The findings indicate the need to explore strategies that address obstacles to receiving confirmatory HIV testing and returning for the results, in addition to the feasibility of a rapid confirmatory HIV test.

Universal access to HIV treatment versus universal 'test and treat': transmission, drug resistance & treatment costs

In South Africa (SA) universal access to treatment for HIV-infected individuals in need has yet to be achieved. Currently ∼1 million receive treatment, but an additional 1.6 million are in need. It is being debated whether to use a universal ‘test and treat’ (T&T) strategy to try to eliminate HIV in SA; treatment reduces infectivity and hence transmission. Under a T&T strategy all HIV-infected individuals would receive treatment whether in need or not. This would require treating 5 million individuals almost immediately and providing treatment for several decades. We use a validated mathematical model to predict impact and costs of: (i) a universal T&T strategy and (ii) achieving universal access to treatment. Using modeling the WHO has predicted a universal T&T strategy in SA would eliminate HIV within a decade, and (after 40 years) cost ∼$10 billion less than achieving universal access. In contrast, we predict a universal T&T strategy in SA could eliminate HIV, but take 40 years and cost ∼$12 billion more than achieving universal access. We determine the difference in predictions is because the WHO has under-estimated survival time on treatment and ignored the risk of resistance. We predict, after 20 years, ∼2 million individuals would need second-line regimens if a universal T&T strategy is implemented versus ∼1.5 million if universal access is achieved. Costs need to be realistically estimated and multiple evaluation criteria used to compare ‘treatment as prevention’ with other prevention strategies. Before implementing a universal T&T strategy, which may not be sustainable, we recommend striving to achieve universal access to treatment as quickly as possible. We predict achieving universal access to treatment would be a very effective ‘treatment as prevention’ approach and bring the HIV epidemic in SA close to elimination, preventing ∼4 million infections after 20 years and ∼11 million after 40 years.

Plasma HIV viral rebound following protocol-indicated cessation of ART commenced in primary and chronic HIV infection

Objectives

The magnitude of HIV viral rebound following ART cessation has consequences for clinical outcome and onward transmission. We compared plasma viral load (pVL) rebound after stopping ART initiated in primary (PHI) and chronic HIV infection (CHI).

Design

Two populations with protocol-indicated ART cessation from SPARTAC (PHI, n = 182) and SMART (CHI, n = 1450) trials.

Methods

Time for pVL to reach pre-ART levels after stopping ART was assessed in PHI using survival analysis. Differences in pVL between PHI and CHI populations 4 weeks after stopping ART were examined using linear and logistic regression. Differences in pVL slopes up to 48 weeks were examined using linear mixed models and viral burden was estimated through a time-averaged area-under-pVL curve. CHI participants were categorised by nadir CD4 at ART stop.

Results

Of 171 PHI participants, 71 (41.5%) rebounded to pre-ART pVL levels, at a median of 50 (95% CI 48–51) weeks after stopping ART. Four weeks after stopping treatment, although the proportion with pVL≥400 copies/ml was similar (78% PHI versus 79% CHI), levels were 0.45 (95% CI 0.26–0.64) log₁₀ copies/ml lower for PHI versus CHI, and remained lower up to 48 weeks. Lower CD4 nadir in CHI was associated with higher pVL after ART stop. Rebound for CHI participants with CD4 nadir >500 cells/mm³ was comparable to that experienced by PHI participants.

Conclusions

Stopping ART initiated in PHI and CHI was associated with viral rebound to levels conferring increased transmission risk, although the level of rebound was significantly lower and sustained in PHI compared to CHI.

Antiviral agents and HIV prevention: controversies, conflicts, and consensus

Antiviral agents can be used to prevent HIV transmission before exposure as preexposure prophylaxis (PrEP), after exposure as postexposure prophylaxis, and as treatment of infected people for secondary prevention. Considerable research has shed new light on antiviral agents for PrEP and for prevention of secondary HIV transmission. While promising results have emerged from several PrEP trials, the challenges of poor adherence among HIV-negative clients and possible increase in sexual risk behaviors remain a concern. In addition, a broader pipeline of antiviral agents for PrEP that focuses on genital tract pharmacology and safety and resistance issues must be developed. Antiretroviral drugs have also been used to prevent HIV transmission from HIV-infected patients to their HIV-discordant sexual partners. The HIV Prevention Trials Network 052 trial demonstrated nearly complete prevention of HIV transmission by early treatment of infection, but the generalizability of the results to other risk groups - including intravenous drug users and MSM - has not been determined. Most importantly, the best strategy for use of antiretroviral agents to reduce the spread of HIV at either the individual level or the population level has not been developed, and remains the ultimate goal of this area of investigation.

Using laboratory surveillance data to estimate engagement in care among persons living with HIV in Los Angeles County, 2009

Poor engagement in HIV care has been associated with delayed access to antiretroviral treatment and increased HIV transmission. Using viral load (VL) results from HIV laboratory surveillance data to conduct longitudinal and cross-sectional analyses, we examined linkage to care, retention in care, and their associated factors in 37,325 persons living with HIV (PLWH) in Los Angeles County (LAC). Linkage to care was considered timely if a VL test result was present ≤3 months of diagnosis. Successful retention in care was defined as having two or more VL test results ≥90 days apart during 2009. Of 6841 persons newly diagnosed with HIV in 2007-2009, 67% were linked to care within 3 months of diagnosis. Factors associated with delayed linkage to care included being African American, Latino, and Asian/Pacific Islander (adjusted hazard ratio [AHR]=0.81; 95% CI=0.75-0.87, AHR=0.83; 95% CI=0.77-0.89, AHR=0.82; 95% CI=0.71-0.94, respectively). Of the 37,325 PLWH, 52% were retained in care during 2009. Factors associated with lack of retention in care included injection drug use (adjusted prevalence ratio [APR]=0.88; 95% CI=0.84-0.93), incarceration at diagnosis (APR=0.56; 95% CI=0.51-0.61), being diagnosed in pre-highly active antiretroviral therapy (HAART) era (APR=0.94; 95% CI=0.92-0.96) or at a public facility (APR=0.97; 95% CI=0.95-1.00), age <45 years (APR=0.87; 95% CI=0.86-0.89), and having concurrent HIV/AIDS diagnoses (APR=0.94; 95% CI=0.92-0.96). This study demonstrates the value of using VL surveillance data to monitor engagement in care among PLWH, and its potential to improve linkage and retention efforts where disparities in care are observed.

Operationalizing treatment as prevention in Los Angeles County: antiretroviral therapy use and factors associated with unsuppressed viral load in the Ryan White system of care

Despite extensive prevention efforts, an estimated 21% of individuals with HIV/AIDS in the United States are unaware of their status, placing them at greater risk for spreading the virus to others. HIV treatment as prevention (TasP) is rapidly becoming an important public health strategy to reduce HIV transmission at the population level. Data for this study were collected on a sample of 11,397 HIV-positive individuals in the Ryan White system, a publicly funded system of care for HIV-positive individuals in Los Angeles County who are uninsured, in 2009 to examine two components of TasP: baseline rates and factors associated with antiretroviral therapy (ART) use and viral load (VL) suppression in a publicly funded system of care. ART coverage among our sample was 90%. In multivariate analyses, those with a higher odds of having unsuppressed VL included: females compared to males (adjusted odds ratio [AOR]=1.25; 95% confidence interval [CI]=1.06, 1.47); African Americans compared to whites (AOR=1.42; 95% CI=1.24, 1.62); men who have sex with men compared to heterosexuals (AOR=1.15; 95% CI=1.00, 1.32); recent substance abusers compared to nonsubstance abusers (AOR=1.35; 95% CI=1.17, 1.55); those recently incarcerated or ever incarcerated compared to those never incarcerated (AOR=1.37; 95% CI=1.15, 1.63; and AOR=1.28; 95% CI=1.09, 1.50); and those retained in care compared to those not retained in care (AOR=1.98; 95% CI=1.76, 2.22). Understanding the key sociodemographic, geographic and behavioral factors associated with ART use as well as HIV VL suppression will be useful for informing the development and deployment of targeted programming and policies that may further enhance the implementation of the TasP approach in communities across the United States.

Switch from 200 to 350 CD4 baseline count: what it means to HIV care and treatment programs in Kenya

INTRODUCTION

With the increasing population of infected individuals in Africa and constrained resources for care and treatment, antiretroviral management continues to be an important public health challenge. Since the announcement of World Health Organization recommendation and guidelines for initiation of antiretroviral Treatment at CD4 count below 350, many developing countries are adopting this strategy in their country specific guidelines to care and treatment of HIV and AIDS. Despite the benefits to these recommendations, what does this switch from 200 to 350 CD4 count mean in antiretroviral treatment demand?

METHODS

A Multi-centre study involving 1376 patients in health care settings in Kenya. CD4 count was carried out by flow cytometry among the HIV infected individuals in Kenya and results analyzed in view of the In-country and the new CD4 recommendation for initiation of antiretroviral treatment.

RESULTS

Across sites, 32% of the individual required antiretroviral at <200 CD4 Baseline, 40% at <250 baseline count and 58% based on the new criteria of <350 CD4 Count. There were more female (68%) than Male (32%).Different from <200 and <250 CD4 baseline criteria, over 50% of all age groups required antiretroviral at 350 CD4 baseline. Age groups between 41-62 led in demand for ART.

CONCLUSION

With the new guidelines, demand for ARVs has more than doubled with variations noted within regions and age groups. As A result, HIV Care and Treatment Programs should prepare for this expansion for the benefits to be realized.

'Slipping through the cracks': policy implications of delays in HIV treatment seeking

Public health initiatives to 'test and treat' HIV-infected persons require understanding HIV care seeking. A study of 101 HIV-infected women receiving anti-retroviral medications in Kampala, Uganda, examined barriers to HIV care. Participants entered HIV/AIDS care late, despite knowing their risk and having sought care for symptoms. Over half of the participants (51%) reported delays of up to 5 years from when they suspected they were infected to seeking an HIV test. Some women reported that they did not perceive a need to be tested because they 'knew' they had HIV due to their partner's death from AIDS. Once tested, delays in entering HIV specific care ranged from less than 6 months to over 5 years. The most common reason reported for entering HIV care was the occurrence of serious or persistent symptoms. Late presentation for HIV care in this cohort is due to the inability of the medical system to link women to appropriate care. Women 'slip through the cracks' of this system, despite their care seeking behaviours. The inability to provide linkage to care is a challenge at the health system level that threatens the success of 'test and treat' protocols.

Viral load monitoring of antiretroviral therapy, cohort viral load and HIV transmission in Southern Africa: a mathematical modelling analysis

OBJECTIVES

In low-income settings, treatment failure is often identified using CD4 cell count monitoring. Consequently, patients remain on a failing regimen, resulting in a higher risk of transmission. We investigated the benefit of routine viral load monitoring for reducing HIV transmission.

DESIGN

Mathematical model.

METHODS

We developed a stochastic mathematical model representing the course of individual viral load, immunological response and survival in a cohort of 1000 HIV-infected patients receiving antiretroviral therapy (ART) in southern Africa. We calculated cohort viral load (CVL; sum of individual viral loads) and used a mathematical relationship between individual viral load values and transmission probability to estimate the number of new HIV infections. Our model was parameterized with data from the International epidemiologic Databases to Evaluate AIDS Southern African collaboration. Sensitivity analyses were performed to assess the validity of the results in a universal 'test and treat' scenario, wherein patients start ART earlier after HIV infection.

RESULTS

If CD4 cell count alone was regularly monitored, the CVL was 2.6 × 10 copies/ml and the treated patients transmitted on average 6.3 infections each year. With routine viral load monitoring, both CVL and transmissions were reduced by 31% to 1.7 × 10 copies/ml and 4.3 transmissions, respectively. The relative reduction of 31% between monitoring strategies remained similar for different scenarios.

CONCLUSION

Although routine viral load monitoring enhances the preventive effect of ART, the provision of ART to everyone in need should remain the highest priority.

Projecting the benefits of antiretroviral therapy for HIV prevention: the impact of population mobility and linkage to care

BACKGROUND

Recent mathematical models suggested that frequent human immunodeficiency virus (HIV) testing with immediate initiation of antiretroviral therapy (ART) to individuals with a positive test result could profoundly curb transmission. The debate about ART as prevention has focused largely on parameter values. We aimed to evaluate structural assumptions regarding linkage to care and population mobility, which have received less attention.

METHODS

We modified the linkage structure of published models of ART as prevention, such that individuals who decline initial testing or treatment do not link to care until late-stage HIV infection. We then added population mobility to the models. We populated the models with demographic, clinical, immigration, emigration, and linkage data from a South African township.

RESULTS

In the refined linkage model, elimination of HIV transmission (defined as an incidence of <0.1%) did not occur by 30 years, even with optimistic assumptions about the linkage rate. Across a wide range of estimates, models were more sensitive to structural assumptions about linkage than to parameter values. Incorporating population mobility further attenuated the reduction in incidence conferred by ART as prevention.

CONCLUSIONS

Linkage to care and population mobility are critical features of ART-as-prevention models. Clinical trials should incorporate relevant data on linkage to care and migration to evaluate the impact of this strategy.

Treatment as prevention: translating efficacy trial results to population effectiveness

PURPOSE OF REVIEW

The understanding that antiretroviral treatment prevents HIV transmission through suppression of viral load provides significant new opportunities in HIV prevention. However, knowledge of efficacy is only a first step to having an impact on the spread of HIV at a population level, the ultimate goal of all primary prevention modalities. This review explores what we know about treatment as prevention and how it could be used as a tool, as part of a combination approach, in the global response to HIV.

RECENT FINDINGS

Efficacy data show that treatment as prevention works at high levels in trial conditions in stable serodiscordant couples; a finding that can reasonably be generalized to other populations at risk of transmitting the virus. Modelling shows that treatment as prevention should have an impact, but the extent of this depends primarily upon whether optimistic or pessimistic assumptions are made about the programmatic use of antiretrovirals (ARVs).

SUMMARY

We describe research questions that need to be addressed in developing optimal programmatic public health treatment strategies including how best to target and implement the use of treatment as prevention, how to balance the needs of treatment for the individual patients' clinical benefit against population level benefits, and how to create programmes that are able to link people to and retain them in care.

Reaping the prevention benefits of highly active antiretroviral treatment: policy implications of HIV Prevention Trials Network 052

PURPOSE OF REVIEW

This review explores the policy implications of findings from the HIV Prevention Trials Network (HPTN 052) treatment as prevention (TasP) study.

RECENT FINDINGS

To date, the potential of antiretrovirals to prevent sexual transmission of HIV by infected persons has been grounded in observational cohort, ecological, mathematical modeling, and meta-analytic studies. HPTN 052 represents the first randomized controlled trial to test the secondary prevention benefit of HIV transmission using antiretroviral treatment in largely asymptomatic persons with high CD4 cell counts.

SUMMARY

The US National HIV/AIDS Strategy has among its key goals the reduction of incident HIV infections, improved access to quality care and associated outcomes, and the reduction in HIV-associated health disparities and inequities. HPTN 052 demonstrates that providing TasP, in combination with other effective prevention strategies offers the promise of achieving these life-saving goals. But HPTN 052 also highlights the need for cautious optimism and underscores the importance of addressing current gaps in the HIV prevention, treatment, and care continuum in order for 'TasP' strategies to achieve their full potential. Among these are necessary improvements in the capacity to expand HIV testing, facilitate effective linkage and retention in care, and improve treatment initiation, maintenance, and virus suppression.

Early identification of HIV: empirical support for jail-based screening

BACKGROUND

Although routine HIV testing is recommended for jails, little empirical data exist describing newly diagnosed individuals in this setting.

METHODS

Client-level data (CLD) are available on a subset of individuals served in EnhanceLink, for the nine of the 10 sites who enrolled newly diagnosed persons in the client level evaluation. In addition to information about time of diagnosis, we analyzed data on initial CD4 count, use of antiretroviral therapy (ART), and linkage to care post discharge. Baseline data from newly diagnosed persons were compared to data from persons whose diagnoses predated jail admission.

RESULTS

CLD were available for 58 newly diagnosed and 708 previously diagnosed individuals enrolled between 9/08 and 3/11. Those newly diagnosed had a significantly younger median age (34 years) when compared to those previously diagnosed (41 years). In the 30 days prior to incarceration, 11% of those newly diagnosed reported injection drug use and 29% reported unprotected anal intercourse. Median CD4 count at diagnosis was 432 cells/mL (range: 22-1,453 cells/mL). A minority (21%, N = 12) of new diagnoses started antiretroviral treatment (ART) before release; 74% have evidence of linkage to community services.

CONCLUSION

Preliminary results from a cross-sectional analysis of this cohort suggest testing in jails finds individuals early on in disease progression. Most HIV(+) detainees did not start ART in jail; therefore screening may not increase pharmacy costs for jails. Detainees newly diagnosed with HIV in jails can be effectively linked to community resources. Jail-based HIV testing should be a cornerstone of "test and treat" strategies.

Effective HIV prevention: the indispensable role of social science

This paper examines the ways in which HIV prevention is understood including “biomedical”, “behavioural”, “structural”, and “combination” prevention. In it I argue that effective prevention entails developing community capacity and requires that public health addresses people not only as individuals but also as connected members of groups, networks and collectives who interact (talk, negotiate, have sex, use drugs, etc.) together. I also examine the evaluation of prevention programmes or interventions and argue that the distinction between efficacy and effectiveness is often glossed and that, while efficacy can be evaluated by randomized controlled trials, the evaluation of effectiveness requires long-term descriptive strategies and/or modelling. Using examples from a number of countries, including a detailed account of the Australian HIV prevention response, effectiveness is shown to be dependent not only on the efficacy of the prevention technology or tool but also on the responses of people – individuals, communities and governments – to those technologies. Whether a particular HIV prevention technology is adopted and its use sustained depends on a range of social, cultural and political factors. The paper concludes by calling on biomedical and social scientists to work together and describes a “social public health”.

Late entry into HIV care: lessons from Brazil, 2003 to 2006

Background

To ascertain the population rates and proportion of late entry into HIV care, as well as to determine whether such late entry correlates with individual and contextual factors.

Methods

Data for the 2003–2006 period in Brazil were obtained from public health records. A case of late entry into HIV care was defined as one in which HIV infection was diagnosed at death, one in which HIV infection was diagnosed after the condition of the patient had already been aggravated by AIDS-related diseases, or one in which the CD4⁺ T-cell count was ≤ 200 cells/mm³ at the time of diagnosis. We also considered extended and stricter sets of criteria (in which the final criterion was ≤ 350 cells/mm³ and ≤ 100 cells/mm³, respectively). The estimated risk ratio was used in assessing the effects of correlates, and the population rates (per 100,000 population) were calculated on an annual basis.

Results

Records of 115,369 HIV-infected adults were retrieved, and 43.6% (50,358) met the standard criteria for late entry into care. Diagnosis at death accounted for 29% (14,457) of these cases. Late entry into HIV care (standard criterion) was associated with certain individual factors (sex, age, and transmission category) and contextual factors (region with less economic development/increasing incidence of AIDS, lower local HIV testing rate, and smaller municipal population). Use of the extended criteria increased the proportion of late entry by 34% but did not substantially alter the correlations analyzed. The overall population rate of late entry was 9.9/100,000 population, specific rates being highest for individuals in the 30–59 year age bracket, for men, and for individuals living in regions with greater economic development/higher HIV testing rates, collectively accounting for more than half of the cases observed.

Conclusions

Although the high proportion of late entry might contribute to spreading the AIDS epidemic in less developed regions, most cases occurred in large cities, with broader availability of HIV testing, and in economically developed regions.

Operational research to improve HIV prevention in the United States

The HIV/AIDS epidemic in the United States continues despite several recent noteworthy advances in HIV prevention. Contemporary approaches to HIV prevention involve implementing combinations of biomedical, behavioral, and structural interventions in novel ways to achieve high levels of impact on the epidemic. Methods are needed to develop optimal combinations of approaches for improving efficiency, effectiveness, and scalability. This article argues that operational research offers promise as a valuable tool for addressing these issues. We define operational research relative to domestic HIV prevention, identify and illustrate how operational research can improve HIV prevention, and pose a series of questions to guide future operational research. Operational research can help achieve national HIV prevention goals of reducing new infections, improving access to care and optimization of health outcomes of people living with HIV, and reducing HIV-related health disparities.

HIV treatment as prevention and HPTN 052

PURPOSE OF REVIEW

This review summarizes the development and implementation of a large clinical trial, HIV Prevention Trials Network (HPTN) 052, whose initial results were recently presented and published.

RECENT FINDINGS

A randomized, clinical trial demonstrated that antiretroviral therapy reduces the sexual transmission of HIV in HIV-serodiscordant couples by more than 96%. The logistical challenges in preparing for and conducting such a trial were considerable.

SUMMARY

HPTN 052 required many years of preparation, considerable collaboration between National Institute of Health and six pharmaceutical companies, and careful ongoing consideration of a large number of ethical issues. HPTN 052 revealed the magnitude of benefit when using antiretroviral therapy to prevent the transmission of HIV, and served as proof of a concept. The results have proven central to the development of new global HIV-prevention efforts.

Expanding ART for treatment and prevention of HIV in South Africa: estimated cost and cost-effectiveness 2011-2050

BACKGROUND

Antiretroviral Treatment (ART) significantly reduces HIV transmission. We conducted a cost-effectiveness analysis of the impact of expanded ART in South Africa.

METHODS

We model a best case scenario of 90% annual HIV testing coverage in adults 15-49 years old and four ART eligibility scenarios: CD4 count <200 cells/mm(3) (current practice), CD4 count <350, CD4 count <500, all CD4 levels. 2011-2050 outcomes include deaths, disability adjusted life years (DALYs), HIV infections, cost, and cost per DALY averted. Service and ART costs reflect South African data and international generic prices. ART reduces transmission by 92%. We conducted sensitivity analyses.

RESULTS

Expanding ART to CD4 count <350 cells/mm(3) prevents an estimated 265,000 (17%) and 1.3 million (15%) new HIV infections over 5 and 40 years, respectively. Cumulative deaths decline 15%, from 12.5 to 10.6 million; DALYs by 14% from 109 to 93 million over 40 years. Costs drop $504 million over 5 years and $3.9 billion over 40 years with breakeven by 2013. Compared with the current scenario, expanding to <500 prevents an additional 585,000 and 3 million new HIV infections over 5 and 40 years, respectively. Expanding to all CD4 levels decreases HIV infections by 3.3 million (45%) and costs by $10 billion over 40 years, with breakeven by 2023. By 2050, using higher ART and monitoring costs, all CD4 levels saves $0.6 billion versus current; other ART scenarios cost $9-194 per DALY averted. If ART reduces transmission by 99%, savings from all CD4 levels reach $17.5 billion. Sensitivity analyses suggest that poor retention and predominant acute phase transmission reduce DALYs averted by 26% and savings by 7%.

CONCLUSION

Increasing the provision of ART to <350 cells/mm3 may significantly reduce costs while reducing the HIV burden. Feasibility including HIV testing and ART uptake, retention, and adherence should be evaluated.

Delayed entry into HIV medical care after HIV diagnosis: risk factors and research methods

Timely linkage to HIV medical care has the potential to improve individual health outcomes and prevent secondary HIV transmission. Recent research found that estimates of delayed care entry varied by study design, with higher estimates among studies using only HIV case surveillance data. In this analysis, we compared the prevalence and risk factors for care delay using data from two studies with different designs conducted in New York City. The Medical Monitoring Project (MMP) used a retrospective design to estimate historical delay among persons currently receiving care, while the Never in Care (NIC) study used a prospective design to estimate current delay status among persons who were care-naive at baseline. Of 513 MMP subjects in 2007-2008, 23% had delayed care entry greater than three months after diagnosis. Independent risk factors for care delay were earlier year of diagnosis and testing positive in a nonmedical environment. Of 28 NIC subjects in 2008-2010, over half had tested positive in a nonmedical environment. The primary-stated reasons for delay were the same in both studies: denial of HIV status and lack of perceived need for medical care. The strengths and weaknesses of surveillance only, prospective, and retrospective study designs with respect to investigating this issue are explored. Future studies and interventions should be mindful of the common selection biases and measurement limitations with each design. A triangulation of estimates from varying designs is suggested for accurately measuring care linkage efforts over time.

The effect of changes in condom usage and antiretroviral treatment coverage on human immunodeficiency virus incidence in South Africa: a model-based analysis

This study aims to assess trends in human immunodeficiency virus (HIV) incidence in South Africa, and to assess the extent to which prevention and treatment programmes have reduced HIV incidence. Two models of the South African HIV epidemic, the STI (sexually transmitted infection)-HIV Interaction model and the ASSA2003 AIDS and Demographic model, were adapted. Both models were fitted to age-specific HIV prevalence data from antenatal clinic surveys and household surveys, using a Bayesian approach. Both models suggest that HIV incidence in 15-49 year olds declined significantly between the start of 2000 and the start of 2008: by 27 per cent (95% CI: 21-32%) in the STI-HIV model and by 31 per cent (95% CI: 23-39%) in the ASSA2003 model, when expressed as a percentage of incidence rates in 2000. By 2008, the percentage reduction in incidence owing to increased condom use was 37 per cent (95% CI: 34-41%) in the STI-HIV model and 23 per cent (95% CI: 14-34%) in the ASSA2003 model. Both models also estimated a small reduction in incidence owing to antiretroviral treatment by 2008. Increased condom use therefore appears to be the most significant factor explaining the recent South African HIV incidence decline.

Advances in the Diagnosis, Treatment and Control of HIV Associated Tuberculosis

There has been an increase in the number of published tuberculosis/HIV (TB/HIV) research findings in recent times. The potential impact of these findings on routine care has informed this review which aims at discussing current concepts and practices underpinning TB/HIV care and control. Any HIV infected person with a cough of any duration is currently considered a TB suspect. Preliminary results also show that the diagnostic yield of same day sputum samples (front loading) is comparable to two-day samples. Laboratory diagnosis is shifting from Ziehl-Neelsen (ZN) smear microscopy and solid culture to fluorescent microscopy, molecular tests and liquid culture. Concomitant TB/HIV therapy improves survival and WHO has recommended ART for all TB/HIV patients. Unless CD4 cell counts are less than 50 cells/µl, ART can be deferred until end of intensive phase. Evidence of survival benefit at high CD4 cell counts is still lacking. New TB drugs and treatment shortening studies are underway but so far no new TB drugs has been added to the current arsenal and treatment duration still remains six months or more. WHO has recommended the 31s (intensified TB case finding, isoniazid prophylaxis and infection control) for TB/HIV control in addition to effective therapy, Antiretroviral therapy and TB vaccines. There has been immense progress in TB/HIV research, however optimal management of HIV-Infected TB patients, will require further research and appropriate translation of emerging evidence to policy and practice.

HIV treatment as prevention: considerations in the design, conduct, and analysis of cluster randomized controlled trials of combination HIV prevention

The rigorous evaluation of the impact of combination HIV prevention packages at the population level will be critical for the future of HIV prevention. In this review, we discuss important considerations for the design and interpretation of cluster randomized controlled trials (C-RCTs) of combination prevention interventions. We focus on three large C-RCTs that will start soon and are designed to test the hypothesis that combination prevention packages, including expanded access to antiretroviral therapy, can substantially reduce HIV incidence. Using a general framework to integrate mathematical modelling analysis into the design, conduct, and analysis of C-RCTs will complement traditional statistical analyses and strengthen the evaluation of the interventions. Importantly, even with combination interventions, it may be challenging to substantially reduce HIV incidence over the 2- to 3-y duration of a C-RCT, unless interventions are scaled up rapidly and key populations are reached. Thus, we propose the innovative use of mathematical modelling to conduct interim analyses, when interim HIV incidence data are not available, to allow the ongoing trials to be modified or adapted to reduce the likelihood of inconclusive outcomes. The preplanned, interactive use of mathematical models during C-RCTs will also provide a valuable opportunity to validate and refine model projections.

Sexual risk behaviors among HIV-infected South African men and women with their partners in a primary care program: implications for couples-based prevention

We studied 1163 sexually-active HIV-infected South African men and women in an urban primary care program to understand patterns of sexual behaviors and whether these behaviors differed by partner HIV status. Overall, 40% reported a HIV-positive partner and 60% a HIV-negative or status unknown partner; and 17.5% reported >2 sex acts in the last 2 weeks, 16.4% unprotected sex in the last 6 months, and 3.7% >1 sex partner in the last 6 months. Antiretroviral therapy (ART) was consistently associated with decreased sexual risk behaviors, as well as with reporting a HIV-negative or status unknown partner. The odds of sexual risk behaviors differed by sex; and were generally higher among participants reporting a HIV-positive partner, but continued among those with a HIV-negative or status unknown partner. These data support ART as a means of HIV prevention. Engaging in sexual risk behaviors primarily with HIV-positive partners was not widely practiced in this setting, emphasizing the need for couples-based prevention.

HIV treatment as prevention: systematic comparison of mathematical models of the potential impact of antiretroviral therapy on HIV incidence in South Africa

BACKGROUND

Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART) on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART.

METHODS AND FINDINGS

Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/µl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y) reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results.

CONCLUSIONS

Mathematical models evaluating the impact of ART vary substantially in structure, complexity, and parameter choices, but all suggest that ART, at high levels of access and with high adherence, has the potential to substantially reduce new HIV infections. There was broad agreement regarding the short-term epidemiologic impact of ambitious treatment scale-up, but more variation in longer term projections and in the efficiency with which treatment can reduce new infections. Differences between model predictions could not be explained by differences in model structure or parameterization that were hypothesized to affect intervention impact.

HIV testing and antiretroviral treatment strategies for prevention of HIV infection: impact on antiretroviral drug resistance

'Test and treat' is a strategy in which widespread screening for human immunodeficiency virus (HIV) is followed by immediate antiretroviral therapy for those testing positive, thereby potentially reducing infectiousness in larger cohorts of infected patients. However, there is a concern that test and treat could lead to increased the levels of transmissible drug-resistant HIV, especially if viral load and/or drug resistance is not routinely monitored. Reviews of the existing literature show that up to now, even in the absence of laboratory tests, drug resistance has not created major problems in sub-Saharan Africa. Here, we discuss the current evidence for the effectiveness of a preventive test and treat approach and the challenges and implications for daily clinical practice and public health.

Estimating the resources required in the roll-out of universal access to antiretroviral treatment in Zimbabwe

OBJECTIVES

To develop projections of the resources required (person-years of drug supply and healthcare worker time) for universal access to antiretroviral treatment (ART) in Zimbabwe.

METHODS

A stochastic mathematical model of disease progression, diagnosis, clinical monitoring and survival in HIV infected individuals.

FINDINGS

The number of patients receiving ART is determined by many factors, including the strategy of the ART programme (method of initiation, frequency of patient monitoring, ability to include patients diagnosed before ART became available), other healthcare services (referral rates from antenatal clinics, uptake of HIV testing), demographic and epidemiological conditions (past and future trends in incidence rates and population growth) as well as the medical impact of ART (average survival and the relationship with CD4 count when initiated). The variations in these factors lead to substantial differences in long-term projections; with universal access by 2010 and no further prevention interventions, between 370 000 and almost 2 million patients could be receiving treatment in 2030-a fivefold difference. Under universal access, by 2010 each doctor will initiate ART for up to two patients every day and the case-load for nurses will at least triple as more patients enter care and start treatment.

CONCLUSIONS

The resources required by ART programmes are great and depend on the healthcare systems and the demographic/epidemiological context. This leads to considerable uncertainty in long-term projections and large variation in the resources required in different countries and over time. Understanding how current practices relate to future resource requirements can help optimise ART programmes and inform long-term public health planning.

Optimal uses of antiretrovirals for prevention in HIV-1 serodiscordant heterosexual couples in South Africa: a modelling study

BACKGROUND

Antiretrovirals have substantial promise for HIV-1 prevention, either as antiretroviral treatment (ART) for HIV-1-infected persons to reduce infectiousness, or as pre-exposure prophylaxis (PrEP) for HIV-1-uninfected persons to reduce the possibility of infection with HIV-1. HIV-1 serodiscordant couples in long-term partnerships (one member is infected and the other is uninfected) are a priority for prevention interventions. Earlier ART and PrEP might both reduce HIV-1 transmission in this group, but the merits and synergies of these different approaches have not been analyzed.

METHODS AND FINDINGS

We constructed a mathematical model to examine the impact and cost-effectiveness of different strategies, including earlier initiation of ART and/or PrEP, for HIV-1 prevention for serodiscordant couples. Although the cost of PrEP is high, the cost per infection averted is significantly offset by future savings in lifelong treatment, especially among couples with multiple partners, low condom use, and a high risk of transmission. In some situations, highly effective PrEP could be cost-saving overall. To keep couples alive and without a new infection, providing PrEP to the uninfected partner could be at least as cost-effective as initiating ART earlier in the infected partner, if the annual cost of PrEP is <40% of the annual cost of ART and PrEP is >70% effective.

CONCLUSIONS

Strategic use of PrEP and ART could substantially and cost-effectively reduce HIV-1 transmission in HIV-1 serodiscordant couples. New and forthcoming data on the efficacy of PrEP, the cost of delivery of ART and PrEP, and couples behaviours and preferences will be critical for optimizing the use of antiretrovirals for HIV-1 prevention. Please see later in the article for the Editors' Summary.

Changes in sexual risk behavior before and after HIV seroconversion in Southern African women enrolled in a HIV prevention trial

BACKGROUND

We examine changes in sexual risk behaviors before and after HIV seroconversion in southern African women enrolled in the Methods for Improving Reproductive Health in Africa trial.

METHODS

HIV testing and counseling, and assessment of sexual behaviors by audio computer-assisted self-interviewing were performed approximately every 3 months. We compared the following sexual behaviors: being sexually active, coital frequency, consistent male condom use, use of any female condoms, anal sex, and >1 sex partner, at study visits before and after HIV seroconversion.

RESULTS

During the trial, 327 women seroconverted to HIV, contributing 718 pre-HIV and 1110 post-HIV study visits. Women were significantly more likely to report consistent condom use at visits after HIV seroconversion compared with visits before HIV infection [adjusted odds ratio, (AOR): 1.36 (95% confidence interval (CI): 1.11 to 1.67)] and were less likely to have >1 male sex partner after serconversion [AOR: 0.66 (95% CI: 0.48 to 0.91)]. Women reported less frequently being sexually active [AOR: 0.63 (95% CI: 0.39 to 1.02)], fewer episodes of sex [>4 sex acts over the past week AOR: 0.74 (95% CI: 0.60 to 0.91)], and a reduction in anal sex [AOR: 0.58 (95% CI: 0.36 to 0.95)] at visits after HIV seroconversion. The observed reductions in sexual risk behaviors persisted over time.

CONCLUSIONS

Women significantly decreased their sexual risk behaviors after HIV seroconversion, but these changes were relatively modest, suggesting the need for further secondary prevention. Timely notification of HIV status coupled with prevention messages can contribute to reductions in sexual risk behaviors.