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

HIV-1 RNA rectal shedding is reduced in men with low plasma HIV-1 RNA viral loads and is not enhanced by sexually transmitted bacterial infections of the rectum

BACKGROUND

Among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM) taking combination antiretroviral therapy (cART), the impact of rectal sexually transmitted infections (STIs) on rectal HIV-1 shedding is unknown.

METHODS

Human immunodeficiency virus type 1 (HIV-1) RNA was quantified from rectal swabs collected for Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) screening of HIV-1-infected MSM. Correlations of STIs with rectal viral load were explored using multinomial regression modeling. HIV-1 coreceptor tropism was predicted from sequencing in a subset of men.

RESULTS

Thirty-one (39%) of 80 men (59 prescribed combination antiretroviral therapy [cART]) had HIV detected in 38 (42%) of 91 rectal swabs. Rectal HIV detection was associated with plasma virus loads above 3.15 log₁₀ copies/mL (95% confidence limit [CL] 2.73, 3.55) and paired rectal viral loads and plasma viral loads were correlated (Kendall's tau [τ] 0.68, Spearman rho [P] = .77). Rectal STIs and abnormal anal cytology were not associated with rectal viral load. HIV coreceptor distribution was very similar between the plasma and rectum in 3 of 4 men.

CONCLUSIONS

Plasma and rectal viral load were correlated, and rectal STIs did not increase the likelihood of detecting HIV in the rectal secretions in MSM, including those with low or undetectable plasma viral load. Suppressing plasma viral load is likely to reduce risk of HIV transmission to insertive partners.

Two sides to the HIV prevention coin: efficacy and effectiveness

In the context of the current concern about HIV prevention efforts, this article addresses the issues of efficacy and effectiveness. We argue that the success of treatments and associated increasing dominance of biomedicine has meant that far too little attention has been paid to effectiveness, that is, to the impact an HIV prevention program or intervention achieves in the real world, under resource constraints, in entire populations. Although biomedicine has, appropriately, investigated the efficacy of a number of new prevention technologies and modeled the impact of "test and treat," issues relating to the provision, acceptability, adoption, and sustained use of prevention technologies, both old and new, have not been fully addressed. As HIV is a profoundly social disease with its causes and consequences deeply embedded in social, cultural and political processes, social scientists need to be heard and work with biomedical scientists to ensure the success of HIV prevention.

Harnessing the prevention benefits of antiretroviral therapy to address HIV and tuberculosis

After 30 years we are still struggling to address a devastating HIV pandemic in which over 25 million people have died. In 2010, an estimated 34 million people were living with HIV, around 70% of whom live in sub-Saharan Africa. Furthermore, in 2009 there were an estimated 1.2 million new HIV-associated TB cases, and tuberculosis (TB) accounted for 24% of HIV-related deaths. By the end of 2010, 6.6 million people were taking antiretroviral therapy (ART), around 42% of those in need as defined by the 2010 World Health Organization (WHO) guidelines. Despite this achievement, around 9 million people were eligible and still in need of treatment, and new infections (approximately 2.6 million in 2010 alone) continue to add to the future caseload. This combined with the international fiscal crisis has led to a growing concern regarding weakening of the international commitment to universal access and delivery of the Millennium Development Goals by 2015. The recently launched UNAIDS/WHO Treatment 2.0 platform calls for accelerated simplification of ART, in line with a public health approach, to achieve and sustain universal access to ART, including maximizing the HIV and TB preventive benefit of ART by treating people earlier, in line with WHO 2010 normative guidance. The potential individual and public health prevention benefits of using treatment in the prevention of HIV and TB enhance the value of the universal access pledge from a life-saving initiative, to a strategic investment aimed at ending the HIV epidemic. This review analyzes the gaps and summarizes the evidence regarding ART in the prevention of HIV and TB.

Modelling the impact of antiretroviral therapy on the epidemic of HIV

Thirty years after HIV first appeared it has killed close to 30 million people but transmission continues unchecked. In 2009, an estimated 1.8 million lives were lost and 2.6 million more people were infected with HIV [1]. To cut transmission, many social, behavioural and biomedical interventions have been developed, tested and tried but have had little impact on the epidemic in most countries. One substantial success has been the development of combination antiretroviral therapy (ART) that reduces viral load and restores immune function. This raises the possibility of using ART not only to treat people but also to prevent new HIV infections. Here we consider the impact of ART on the transmission of HIV and show how it could help to control the epidemic. Much needs to be known and understood concerning the impact of early treatment with ART on the prognosis for individual patients and on transmission. We review the current literature on factors associated with modelling treatment for prevention and illustrate the potential impact using existing models. We focus on generalized epidemics in sub- Saharan Africa, with an emphasis on South Africa, where transmission is mainly heterosexual and which account for an estimated 17% of all people living with HIV. We also make reference to epidemics among men who have sex with men and injection drug users where appropriate. We discuss ways in which using treatment as prevention can be taken forward knowing that this can only be the beginning of what must become an inclusive dialogue among all of those concerned to stop acquired immune deficiency syndrome (AIDS).

Universal testing and treatment as an HIV prevention strategy: research questions and methods

Achieving high coverage of antiretroviral treatment (ART) in resource-poor settings will become increasingly difficult unless HIV incidence can be reduced substantially. Universal voluntary counselling and testing followed by immediate initiation of ART for all those diagnosed HIV-positive (universal testing and treatment, UTT) has the potential to reduce HIV incidence dramatically but would be very challenging and costly to deliver in the short term. Early modelling work in this field has been criticised for making unduly optimistic assumptions about the uptake and coverage of interventions. In future work, it is important that model parameters are realistic and based where possible on empirical data. Rigorous research evidence is needed before the UTT approach could be considered for wide-scale implementation. This paper reviews the main areas that need to be explored. We consider in turn research questions related to the provision of services for universal testing, services for immediate treatment of HIV-positives and the population-level impact of UTT, and the research methods that could be used to address these questions. Ideally, initial feasibility studies should be carried out to investigate the acceptability, feasibility and uptake of UTT services. If these studies produce promising results, there would be a strong case for a cluster-randomised trial to measure the impact of a UTT intervention on HIV incidence, and we consider the main design features of such a trial.

Antiretroviral therapy: a key component of a comprehensive HIV prevention strategy

Transmission of HIV is critically dependent on the level of HIV viral load within blood and genital secretions. Antiretroviral therapy results in sustained reductions in viral load to undetectable levels. Thus, antiretroviral therapy has long been postulated as a potential means to curb HIV transmission. Observational data have now confirmed that antiretroviral therapy is associated with a decrease in transmission among heterosexual serodiscordant couples, injection-drug users, and in population-based studies. Mathematical models suggest that further expansion of antiretroviral coverage within current guidelines can play a major role in controlling the spread of HIV. Concerns regarding the potential for transmission during acute HIV infection, behavioral disinhibition, and resistance to overcome the impact of treatment on prevention have not materialized to date. The Joint United Nations AIDS (UNAIDS) program has called for the inclusion of antiretroviral treatment as a key pillar in the global strategy to control the spread of HIV infection.

Uptake of biomedical interventions for prevention of sexually transmitted HIV

PURPOSE OF THE REVIEW

To examine the population-level effects of introducing and/or expanding biomedical interventions for prevention of human immunodeficiency virus (HIV) sexually transmitted infections through mathematical modeling.

RECENT FINDINGS

Successes of several ground-breaking clinical trials have invigorated the field of HIV prevention with new enthusiasm and opportunities for research into and application of biomedical HIV prevention. Mathematical modeling has advanced in tandem with valuable contributions to both investigative science and public health. New models provide qualitative and quantitative insights regarding the epidemiological impact of the uptake of biomedical interventions, singly and/or in combination including treatment of sexually transmitted infections, condom use, male circumcision, antiretroviral treatment and pre-exposure prophylaxis and vaccine for HIV prevention.

SUMMARY

Biomedical interventions are critical for reversing the HIV pandemic. Mathematical modeling is invaluable for informed biomedical HIV prevention research, policy and practice.

Interaction of mathematical modeling and social and behavioral HIV/AIDS research

PURPOSE OF REVIEW

HIV is transmitted within complex biobehavioral systems. Mathematical modeling can provide insight to complex population-level outcomes of various behaviors measured at an individual level.

RECENT FINDINGS

HIV models in the social and behavioral sciences can be categorized in a number of ways; here, we consider two classes of applications common in the field generally, and in the past year in particular: those models that explore significant behavioral determinants of HIV disparities within and between populations; and those models that seek to evaluate the potential impact of specific social and behavioral interventions.

SUMMARY

We discuss two overarching issues we see in the field: the need to further systematize effectiveness models of behavioral interventions, and the need for increasing investigation of the use of behavioral data in epidemic models. We believe that a recent initiative by the National Institutes of Health will qualitatively change the relationships between epidemic modeling and sociobehavioral prevention research in the coming years.

The impact of the new WHO antiretroviral treatment guidelines on HIV epidemic dynamics and cost in South Africa

Background

Since November 2009, WHO recommends that adults infected with HIV should initiate antiretroviral therapy (ART) at CD4+ cell counts of ≤350 cells/µl rather than ≤200 cells/µl. South Africa decided to adopt this strategy for pregnant and TB co-infected patients only. We estimated the impact of fully adopting the new WHO guidelines on HIV epidemic dynamics and associated costs.

Methods and Finding

We used an established model of the transmission and control of HIV in specified sexual networks and healthcare settings. We quantified the model to represent Hlabisa subdistrict, KwaZulu-Natal, South Africa. We predicted the HIV epidemic dynamics, number on ART and program costs under the new guidelines relative to treating patients at ≤200 cells/µl for the next 30 years. During the first five years, the new WHO treatment guidelines require about 7% extra annual investments, whereas 28% more patients receive treatment. Furthermore, there will be a more profound impact on HIV incidence, leading to relatively less annual costs after seven years. The resulting cumulative net costs reach a break-even point after on average 16 years.

Conclusions

Our study strengthens the WHO recommendation of starting ART at ≤350 cells/µl for all HIV-infected patients. Apart from the benefits associated with many life-years saved, a modest frontloading appears to lead to net savings within a limited time-horizon. This finding is robust to alternative assumptions and foreseeable changes in ART prices and effectiveness. Therefore, South Africa should aim at rapidly expanding its healthcare infrastructure to fully embrace the new WHO guidelines.

The effect of expanded antiretroviral treatment strategies on the HIV epidemic among men who have sex with men in San Francisco

Modeling of expanding antiretroviral treatment to all HIV infected adults already in care in San Francisco predicts reductions in new HIV infections at 5 years of 59% among men who have sex with men (MSM). Addition of annual HIV testing for MSM to universal treatment decreases new infections by 76%.

(See editorial commentary by DeGruttola and Schooley on pages 1050–1052.)

Modeling of expanding antiretroviral treatment to all HIV-infected adults already in care in San Francisco predicts reductions in new HIV infection at 5 years of 59% among men who have sex with men. Addition of annual HIV testing for men who have sex with men to universal treatment decreases new infections by 76%.

The role of acute and early HIV infection in the spread of HIV and implications for transmission prevention strategies in Lilongwe, Malawi: a modelling study

BACKGROUND

HIV transmission risk is higher during acute and early HIV infection than it is during chronic infection, but the contribution of early infection to the spread of HIV is controversial. We estimated the contribution of early infection to HIV incidence in Lilongwe, Malawi, and predict the future effect of hypothetical prevention interventions targeted at early infection only, chronic infection only, or both stages.

METHODS

We developed a deterministic mathematical model describing heterosexual HIV transmission, informed by detailed behavioural and viral-load data collected in Lilongwe. We included sexual contact within and outside of steady pairs and divided the infectious period into intervals to allow for changes in transmissibility by infection stage. We used a Bayesian melding approach to fit the model to HIV prevalence data collected between 1987 and 2005 at Lilongwe antenatal clinics. We assessed interventions that reduced the per-contact transmission probability to 0.00003 in people receiving them, and varied the proportion of individuals receiving the intervention in each stage.

FINDINGS

We estimated that 38.4% (95% credible interval 18.6-52.3) of HIV transmissions in Lilongwe are attributable to sexual contact with individuals with early infection. Interventions targeted at only early infection substantially reduced HIV prevalence, but did not lead to elimination, even with 100% coverage. Interventions targeted at only chronic infections also reduced HIV prevalence, but coverage levels of 95-99% were needed for the elimination of HIV. In scenarios with less than 95% coverage of interventions targeted at chronic infections, additional interventions reaching 25-75% of individuals with early infection reduced HIV prevalence substantially.

INTERPRETATION

Our results suggest that early infection plays an important part in HIV transmission in this sub-Saharan African setting. Without near-complete coverage, interventions during chronic infection will probably have incomplete effectiveness unless complemented by strategies targeting individuals with early HIV infection.

FUNDING

National Institutes of Health, University of North Carolina Center for AIDS Research.

Comprehensive Approaches to the Diagnosis and Treatment of HIV Infection in the Community: Can "Seek and Treat" Really Deliver?

For every two people starting on combination antiretroviral therapy (cART), five become infected with HIV. Current prevention strategies are inadequate, and it has been hypothesized that cART itself could be used as a tool for prevention, in combination with enhanced testing and access to treatment-the "seek and treat" approach. Ecologic and modeling data support this strategy, but many questions remain: how to optimize HIV testing, cART uptake and adherence, how to deal with treatment failure and toxicity, and how to implement integrated prevention strategies and deal with key comorbidities. Pilot studies (eg, HIV Prevention Trials Network 065) are underway to validate the approach under controlled circumstances before it is integrated into public health policy. As we redefine the potential benefits of cART on a broader scale, let us not sacrifice the gains that have been made until we are more certain of the potential benefits of the "seek and treat" strategy.

Treatment as prevention: preparing the way

Potent antiretroviral therapy (ART) reduces mortality and morbidity in people living with HIV by reducing viral load and allowing their immune systems to recover. The reduction in viral load soon after starting ART has led to the hypothesis that early and widespread ART could prevent onward transmission and therefore eliminate the HIV epidemic in the long term. While several authors have argued that it is feasible to use HIV treatment as prevention (TasP), provided treatment is started sufficiently early, others have reasonably drawn attention to the many operational difficulties that will need to be overcome if the strategy is to succeed in reducing HIV transmission. Furthermore, international public health policy must be based on more than theoretical studies, no matter how appealing. Community randomized controlled trials provide the gold standard for testing the extent to which early treatment reduces incidence, but much still needs to be understood and the immediate need is for operational studies to explore the practical feasibility of this approach. Here, we examine some of the issues to be addressed, the obstacles to be overcome, and strategies that may be necessary if TasP is to be effective. Studies of this kind will provide valuable information for the design of large-scale trials, as well as essential information that will be needed if early treatment is to be incorporated into public health policy.

The potential impact of an HIV vaccine with limited protection on HIV incidence in Thailand: a modeling study

BACKGROUND

The RV144 trial on the ALVAC/AIDSVAX candidate HIV vaccine, carried out in Thailand, showed short-lived protection against infection.

METHODS

Using a deterministic compartmental model we explored the potential impact of this vaccine on heterosexual HIV transmission in Thailand. Both one-off vaccination strategies, as well as strategies with regular boosting, either annually or every two years, were explored. Both targeting the general adult population and prioritizing sex workers were modeled. The impact of risk compensation among high risk groups, as well as whether higher levels of safe sex in high risk groups could be an alternative to vaccination, was studied.

RESULTS

One-off vaccination campaigns had only transient effects, and boosting appears to be a key component of successful vaccination campaigns. Intensive vaccination campaigns may reduce HIV incidence by up to 75% after 10 years of vaccination. Targeting only sex workers has a smaller impact but has a more favorable cost-benefit ratio. Risk compensation has the potential of undoing much of the benefits of a vaccination program and may even increase incidence. In contrast, higher levels of safe sex among sex workers would provide a viable alternative to vaccinating this group.

DISCUSSION

The new vaccine holds promise for controlling HIV in Thailand and similar countries. In view of the short lived protection of the vaccine, regular boosting of immunity as well as avoidance of risk compensation are essential. Targeting sex workers would achieve the greatest reduction in incidence per vaccination and may be considered for expensive vaccines but its cost-effectiveness has to be compared to alternatives.

The spectrum of engagement in HIV care and its relevance to test-and-treat strategies for prevention of HIV infection

For individuals with human immunodeficiency virus (HIV) infection to fully benefit from potent combination antiretroviral therapy, they need to know that they are HIV infected, be engaged in regular HIV care, and receive and adhere to effective antiretroviral therapy. Test-and-treat strategies for HIV prevention posit that expanded testing and earlier treatment of HIV infection could markedly decrease ongoing HIV transmission, stemming the HIV epidemic. However, poor engagement in care for HIV-infected individuals will substantially limit the effectiveness of test-and-treat strategies. We review the spectrum of engagement in care for HIV-infected individuals in the United States and apply this information to help understand the magnitude of the challenges that poor engagement in care will pose to test-and-treat strategies for HIV prevention.

Interventions for families affected by HIV

Family-based interventions are efficacious for human immunodeficiency virus (HIV) detection, prevention, and care, but they are not broadly diffused. Understanding intervention adaptation and translation processes can support evidence-based intervention (EBI) diffusion processes. This paper provides a narrative review of a series of EBI for families affected by HIV (FAH) that were adapted across five randomized controlled trials in the US, Thailand, and South Africa over 15 years. The FAH interventions targeted parents living with HIV and their children or caregiver supports. Parents with HIV were primarily mothers infected through sexual transmission. The EBIs for FAH are reviewed with attention to commonalities and variations in risk environments and intervention features. Frameworks for common and robust intervention functions, principles, practice elements, and delivery processes are utilized to highlight commonalities and adaptations for each location, time period, and intervention delivery settings. Health care, housing, food, and financial security vary dramatically in each risk environment. Yet, all FAH face common health, mental health, transmission, and relationship challenges. The EBIs efficaciously addressed these common challenges and were adapted across contexts with fidelity to robust intervention principles, processes, factors, and practices. Intervention adaptation teams have a series of structural decision points: mainstreaming HIV with other local health priorities or not; selecting an optimal delivery site (clinics, homes, community centers); and how to translate intervention protocols to local contexts and cultures. Replication of interventions with fidelity must occur at the level of standardized functions and robust principles, processes, and practices, not manualized protocols. Adopting a continuous quality improvement paradigm will enhance rapid and global diffusion of EBI for FAH.

Combination HIV prevention: significance, challenges, and opportunities

No single HIV prevention strategy will be sufficient to control the HIV pandemic. However, a growing number of interventions have shown promise in partially protecting against HIV transmission and acquisition, including knowledge of HIV serostatus, behavioral risk reduction, condoms, male circumcision, needle exchange, treatment of curable sexually transmitted infections, and use of systemic and topical antiretroviral medications by both HIV-infected and uninfected persons. Designing the optimal package of interventions that matches the epidemiologic profile of a target population, delivering that package at the population level, and evaluating safety, acceptability, coverage, and effectiveness, all involve methodological challenges. Nonetheless, there is an unprecedented opportunity to develop "prevention packages" that combine various arrays of evidence-based strategies, tailored to the needs of diverse subgroups and targeted to achieve high coverage for a measurable reduction in population-level HIV transmission. HIV prevention strategies that combine partially effective interventions should be scaled up and evaluated.

'Test-and-treat': the end of the HIV epidemic?

PURPOSE OF REVIEW

The aim is to review recent literature on 'test-and-treat', a prevention strategy that promotes high levels of HIV testing and initiating antiretroviral therapy upon diagnosis, regardless of CD4 cell count. Antiretroviral therapy (ART) has been shown to dramatically reduce viral load which is strongly associated with the risk of transmission, therefore there is the potential to reduce HIV transmissions with ART.

RECENT FINDINGS

Recent papers from observational studies on heterosexual sero-discordant couples found an overall rate of transmission of HIV-1 from ART-treated patients of 0.46 per 100 person-years, confirming the possibility of using ART as a prevention strategy. Several models have been used to predict the effect of this strategy and the potential risks of it. Randomized controlled trials are currently ongoing investigating the effect of ART on reducing infectiousness and the feasibility of this policy.

SUMMARY

More precise estimations of the transmission risk under virally suppressive ART (especially in MSM) and of change in sex risk behaviour at diagnosis and at start of ART are needed. Further, the benefit to individual health of very early ART initiation and the feasibility of this policy need to be evaluated. Achieving very high levels of testing should be a high priority due to the benefits of initiating ART in all those who are in need (CD4 cell count < 350 cells/μl) and potential benefits on incidence due to reductions in risk behaviour in those diagnosed. Use of ART immediately at diagnosis in those with high CD4 cell counts should await results from further studies.

CD4 cell eligibility thresholds: an analysis of the time to antiretroviral treatment in HIV-1 seroconverters

BACKGROUND

WHO recommends initiating combination antiretroviral treatment at the minimal CD4 cell threshold of 350 cells/μl. In sub-Saharan Africa, the time for a recently infected patient to reach this threshold is unclear.

METHOD

We estimated the probability of reaching different CD4 cell thresholds over time in the ANRS 1220 cohort of HIV-1 seroconverters in Côte d'Ivoire. CD4 cell slopes were estimated using a mixed linear model. Probabilities of crossing the 350 and 500 cells/μl CD4 cell thresholds were estimated by the Kaplan-Meier method.

RESULTS

Between 1997 and 2009, 304 recent seroconverters have been enrolled in the Primo-CI cohort (62% men, median baseline age 29 years and median time since the estimated date of seroconversion 9 months). The probability of having a first CD4 cell count below 500 cells/μl was 0.57, 0.72, 0.79 and 0.84 at study entry, 2, 4 and 6 years, respectively. For a first CD4 cell count below 350 cells/μl, these figures were 0.29, 0.40, 0.55 and 0.67. The time for 75% of patients to reach the threshold was 3.0 years for 500 cells/μl and 7.0 years for 350 cells/μl.

What do mathematical models tell us about the emergence and spread of drug-resistant HIV?

PURPOSE OF REVIEW

To discuss recent HIV epidemic models examining the transmission of antiretroviral (ARV) drug resistance.

RECENT FINDINGS

A relatively small number of recent transmission models have investigated ARV resistance in the context of therapeutic, combined ART (cART); ARV-vaginal microbicides (ARV-VMB); and oral pre-exposure prophylaxis (PrEP). Models of cART use have highlighted potential concerns about future resistance transmission, particularly in resource-constrained settings, and have emphasized the benefits of viral load monitoring in limiting resistance spread. PrEP models have concluded that inadvertent use by HIV-infected individuals could increase resistance prevalence, and that risk compensation by PrEP users could limit their beneficial effects on HIV transmission. ARV-VMB models have demonstrated that whereas resistance can reduce prophylactic effectiveness in preventing HIV acquisition of female ARV-VMB users, it may concomitantly benefit users' male partners if the resistant strains that female users acquire are less transmissible than wild-type strains. The models have examined the balance between these two factors at the population level.

SUMMARY

Recent HIV transmission models have adopted a wide assortment of structures and assumptions to explore drug resistance in the context of different ARV interventions in various settings. There is a need for future work emphasizing the simultaneous effects of multiple ARV interventions, as well as the public health impact of resistance, not just its prevalence.

Factors associated with utilization of HAART amongst hard-to-reach HIV-infected individuals in Atlanta, Georgia

The study is aimed at identifying clinical, demographic and behavioral factors, including participation in HIV care, associated with the utilization of antiretroviral therapy (ART), among hard-to-reach HIV-positive individuals in Atlanta, GA. The study included 184 HIV-positive participants of the Infectious Disease Program (IDP) of the Grady Health System between February 1999 to March 2001. Individuals were categorized as regular attendees (those who consistently kept their outpatient appointments, n = 65), irregular (those who inconsistently kept their appointments, n = 60) or non-attendees (those who failed routinely to keep their appointments, n = 59). Univariate and multivariate analyses using log-binomial regression modeling were done. HIV-infected individuals who consistently kept their appointments at the IDP received ART at a frequency (86%) that is twice that of those who missed some appointments (42%) and four times that of those who routinely failed to keep appointments (20%). In multivariate analysis, category of clinic attendance (regular, irregular or non-attendee) was the only risk factor independently associated with utilization of ART: Regular attendees (RR = 3.59, 95% CI 2.12 to 6.08) and irregular attendees (RR = 2.26, 95% CI 1.28 to 4.01) compared to non-attendees. The positive association between routine clinic attendance and use of antiretroviral therapy observed in this study should encourage the development of strategies to retain patients in outpatient HIV care.

Who gets tested for HIV in a South African urban township? Implications for test and treat and gender-based prevention interventions

BACKGROUND

With increasing calls for linking HIV-infected individuals to treatment and care via expanded testing, we examined sociodemographic and behavioral characteristics associated with HIV testing among men and women in Soweto, South Africa.

METHODS

We conducted a cross-sectional household survey involving 1539 men and 1877 women as part of the community-randomized prevention trial Project ACCEPT/HPTN043 between July 2007 to October 2007. Multivariable logistic regression models, stratified by sex, assessed factors associated with HIV testing and then repeated testing.

RESULTS

Most women (64.8%) and 28.9% of men reported ever having been tested for HIV, among whom 57.9% reported repeated HIV testing. In multivariable analyses, youth and students had a lower odds of HIV testing. Men and women who had conversations about HIV/AIDS with increasing frequency and who had heard about antiretroviral therapy were more likely to report HIV testing, and repeated testing. Men who had ≥ 12 years of education and who were of high socioeconomic status, and women who were married, who were of low socioeconomic status, and who had children under their care had a higher odds of HIV testing. Women, older individuals, those with higher levels of education, married individuals, and those with children under their care had a higher odds of reporting repeated HIV testing. Uptake of HIV testing was not associated with condom use, having multiple sex partners, and HIV-related stigma.

CONCLUSIONS

Given the low uptake of HIV testing among men and youth, further targeted interventions could facilitate a test and treat strategy among urban South Africans.

Increased HIV testing and reduced undiagnosed infection among gay men in Scotland, 2005-8: support for the opt-out testing policy?

Objective

To examine changes in HIV testing and undiagnosed infection among men who have sex with men in Scotland between 2005 and 2008.

Methods

Self-completed questionnaires and Orasure oral fluid collection kits were distributed to men visiting the commercial gay scene in Glasgow and Edinburgh.

Results

Questionnaires and oral fluid specimens were provided by 1350 men (51.6% response rate) in 2005 and 1277 (59.7% response rate) in 2008. 2572 men were eligible for inclusion in the analyses. Recent HIV testing increased from 33.2% in 2005 to 48.3% in 2008 (p<0.001). HIV prevalence was comparable in 2005 and 2008 (4.4% and 4.6%, respectively). Among HIV-positive men, there was a reduction in undiagnosed infection between 2005 and 2008 from 41.7% to 26.3% (p=0.08). Undiagnosed HIV did not differ between men who were and were not tested in the past year. In 2008, only four (26.7%) HIV-positive men tested in the past 6 months were undiagnosed, compared with 11 (42.3%) HIV-positive men who had not tested (p=0.03).

Conclusion

There was a substantial increase in recent HIV testing between 2005 and 2008. Although there was a concurrent (non-significant) reduction in undiagnosed HIV, there was no difference in undiagnosed infection between men who had and had not tested recently. However, lower proportions of undiagnosed infection among the most recent HIV-positive testers suggest frequent testing could play a role in reducing undiagnosed HIV and should remain central to HIV prevention efforts.

Contact with HIV prevention services highest in gay and bisexual men at greatest risk: cross-sectional survey in Scotland

BACKGROUND

Men who have sex with men (MSM) remain the group most at risk of acquiring HIV in the UK and new HIV prevention strategies are needed. In this paper, we examine what contact MSM currently have with HIV prevention activities and assess the extent to which these could be utilised further.

METHODS

Anonymous, self-complete questionnaires and Orasure™ oral fluid collection kits were distributed to men visiting the commercial gay scenes in Glasgow and Edinburgh in April/May 2008. 1508 men completed questionnaires (70.5% response rate) and 1277 provided oral fluid samples (59.7% response rate); 1318 men were eligible for inclusion in the analyses.

RESULTS

82.5% reported some contact with HIV prevention activities in the past 12 months, 73.1% obtained free condoms from a gay venue or the Internet, 51.1% reported accessing sexual health information (from either leaflets in gay venues or via the Internet), 13.5% reported talking to an outreach worker and 8.0% reported participating in counselling on sexual health or HIV prevention. Contact with HIV prevention activities was associated with frequency of gay scene use and either HIV or other STI testing in the past 12 months, but not with sexual risk behaviours. Utilising counselling was also more likely among men who reported having had an STI in the past 12 months and HIV-positive men.

CONCLUSIONS

Men at highest risk, and those likely to be in contact with sexual health services, are those who report most contact with a range of current HIV prevention activities. Offering combination prevention, including outreach by peer health workers, increased uptake of sexual health services delivering behavioural and biomedical interventions, and supported by social marketing to ensure continued community engagement and support, could be the way forward. Focused investment in the needs of those at highest risk, including those diagnosed HIV-positive, may generate a prevention dividend in the long term.

Antiretroviral therapy: a promising HIV prevention strategy?

The use of antiretroviral therapy (ART) has been associated with significant improvement in morbidity and survival of persons living with HIV. In addition, recently, there has also been intense interest in the potential impact of ART on HIV transmission and consequently on the trajectory of the HIV epidemic globally. Evidence from mathematical modeling analyses and observational and ecological studies supports the potential for ART as prevention. However, definitive data from clinical trials are awaited. In the United States, the feasibility and potential of using ART as a prevention strategy presents particular challenges: the large number of individuals with undiagnosed HIV; the predominance of disenfranchised individuals affected by the epidemic; evidence of delay in engagement in HIV care after diagnosis with attendant late initiation of ART; and difficulties with consistent long-term adherence to ART and concerns regarding long-term risk-behavior change. Thus, for this novel effort to succeed, a multidimensional approach is necessary that must include policy changes, social mobilization, and improved access to clinical and supportive services for persons living with HIV, with a particular focus on the unique needs of at-risk populations, combined with engagement of all cadres of health care providers and community constituencies.

Antiretroviral therapy needs: the effect of changing global guidelines

BACKGROUND

In 2010 the WHO issued a revision of the guidelines on antiretroviral therapy (ART) for HIV infection in adults and adolescents. The recommendations included earlier diagnosis and treatment of HIV in the interest of a longer and healthier life. The current analysis explores the impact on the estimates of treatment needs of the new criteria for initiating ART compared with the previous guidelines.

METHODS

The analyses are based on the national models of HIV estimates for the years 1990-2009. These models produce time series estimates of ART treatment need and HIV-related mortality. The ART need estimates based on ART eligibility criteria promoted by the 2010 WHO guidelines were compared with the need estimates based on the 2006 WHO guidelines.

RESULTS

With the 2010 eligibility criteria, the proportion of people living with HIV currently in need of ART is estimated to increase from 34% to 49%. Globally, the need increases from 11.4 million (10.2-12.5 million) to 16.2 million (14.8-17.1 million). Regional differences include 7.4 million (6.4-8.4 million) to 10.6 million (9.7-11.5 million) in sub-Saharan Africa, 1.6 million (1.3-1.7 million) to 2.4 million (2.1-2.5 million) in Asia and 710 000 (610 000-780 000) to 950 000 (810 000-1.0 million) in Latin America and the Caribbean.

CONCLUSIONS

When adopting the new recommendations, countries have to adapt their planning process in order to accelerate access to life saving drugs to those in need. These recommendations have a significant impact on resource needs. In addition to improving and prolonging the lives of the infected individuals, it will have the expected benefit of reducing HIV transmission and the future HIV/AIDS burden.

Challenges of a hidden epidemic: HIV prevention among women in the United States

HIV/AIDS trends in the United States depict a concentrated epidemic with hot spots that vary by location, poverty, race/ethnicity, and transmission mode. HIV/AIDS is a leading cause of death among US women of color; two-thirds of new infections among women occur in black women, despite the fact that black women account for just 14% of the US female population. The gravity of the HIV epidemic among US women is often not appreciated by those at risk and by the broader scientific community. We summarize the current epidemiology of HIV/AIDS among US women and discuss clinical, research, and public health intervention components that must be brought together in a cohesive plan to reduce new HIV infections in US women. Only by accelerating research and programmatic efforts will the hidden epidemic of HIV among US women emerge into the light and come under control.

Entry and retention in medical care among HIV-diagnosed persons: a meta-analysis

OBJECTIVE

A 'test and treat' strategy to reduce HIV transmission hinges on linking and retaining HIV patients in care to achieve the full benefit of antiretroviral therapy. We integrated empirical findings and estimated the percentage of HIV-positive persons in the United States who entered HIV medical care soon after their diagnosis; and were retained in care during specified assessment intervals.

METHODS

We comprehensively searched databases and bibliographic lists to identify studies that collected data from May 1995 through 2009. Separate meta-analyses were conducted for entry into care and retention in care (having multiple HIV medical visits during specified assessment intervals) stratified by methodological variables. All analyses used random-effects models.

RESULTS

Overall, 69% [95% confidence interval (CI) 66-71%, N = 53 323, 28 findings] of HIV-diagnosed persons in the United States entered HIV medical care averaged across time intervals in the studies. Seventy-two percent (95% CI 67-77%, N = 6586, 12 findings) entered care within 4 months of diagnosis. Seventy-six percent (95% CI 66-84%, N = 561, 15 findings) entered care after testing HIV-positive in emergency/urgent care departments and 67% (95% CI 64-70%, N = 52 762, 13 findings) entered care when testing was done in community locations. With respect to retention in care, 59% (95% CI 53-65%, N = 75 655, 28 findings) had multiple HIV medical care visits averaged across assessment intervals of 6 months to 3-5 years. Retention was lower during longer assessment intervals.

CONCLUSION

Entry and retention in HIV medical care in the United States are moderately high. Improvement in both outcomes will increase the success of a test and treat strategy.

Decreased sexual risk behavior in the era of HAART among HIV-infected urban and rural South Africans attending primary care clinics

OBJECTIVE

In light of increasing access to HAART in sub-Saharan Africa, we conducted a longitudinal study to assess the impact of HAART on sexual risk behaviors among HIV-infected South Africans in urban and rural primary care clinics.

DESIGN

Prospective observational cohort.

METHODS

We conducted a cohort study at rural and urban primary care HIV clinics in South Africa consisting of 1544 men and 4719 women enrolled from 2003 to 2010, representing 19703 clinic visits. The primary outcomes were being sexually active, unprotected sex, and more than one sex partner and were evaluated at 6 monthly intervals. Generalized estimated equations assessed the impact of HAART on sexual risk behaviors.

RESULTS

Among 6263 HIV-infected men and women, over a third (37.2%) initiated HAART during study follow-up. In comparison to pre-HAART follow-up, visits while receiving HAART were associated with a decrease in those reporting being sexually active [adjusted odds ratio: 0.86 (95% confidence interval: 0.78-0.95)]. Unprotected sex and having more than one sex partner were reduced at visits following HAART initiation compared to pre-HAART visits [adjusted odds ratio: 0.40 (95% confidence interval: 0.34-0.46) and adjusted odds ratio: 0.20 (95% confidence interval: 0.14-0.29), respectively].

CONCLUSION

Sexual risk behavior significantly decreased following HAART initiation among HIV-infected South African men and women in primary care programs. The further expansion of antiretroviral treatment programs could enhance HIV prevention efforts in Africa.

Evaluating the cost-effectiveness of pre-exposure prophylaxis (PrEP) and its impact on HIV-1 transmission in South Africa

BACKGROUND

Mathematical modelers have given little attention to the question of how pre-exposure prophylaxis (PrEP) may impact on a generalized national HIV epidemic and its cost-effectiveness, in the context of control strategies such as condom use promotion and expanding ART programs.

METHODOLOGY/PRINCIPAL FINDINGS

We use an age- and gender-structured model of the generalized HIV epidemic in South Africa to investigate the potential impact of PrEP in averting new infections. The model utilizes age-structured mortality, fertility, partnership and condom use data to model the spread of HIV and the shift of peak prevalence to older age groups. The model shows that universal PrEP coverage would have to be impractically high to have a significant effect on incidence reduction while ART coverage expands. PrEP targeted to 15-35-year-old women would avert 10%-25% (resp. 13%-28%) of infections in this group and 5%-12% (resp. 7%-16%) of all infections in the period 2014-2025 if baseline incidence is 0.5% per year at 2025 (resp. 0.8% per year at 2025). The cost would be $12,500-$20,000 per infection averted, depending on the level of ART coverage and baseline incidence. An optimistic scenario of 30%-60% PrEP coverage, efficacy of at least 90%, no behavior change among PrEP users and ART coverage less than three times its 2010 levels is required to achieve this result. Targeting PrEP to 25-35-year-old women (at highest risk of infection) improves impact and cost-effectiveness marginally. Relatively low levels of condom substitution (e.g., 30%) do not nullify the efficacy of PrEP, but reduces cost-effectiveness by 35%-40%.

CONCLUSIONS/SIGNIFICANCE

PrEP can avert as many as 30% of new infections in targeted age groups of women at highest risk of infection. The cost-effectiveness of PrEP relative to ART decreases rapidly as ART coverage increases beyond three times its coverage in 2010, after which the ART program would provide coverage to more than 65% of HIV(+) individuals. To have a high relative cost-effective impact on reducing infections in generalized epidemics, PrEP must utilize a window of opportunity until ART has been scaled up beyond this level.

Antiretroviral therapy for tuberculosis control in nine African countries

HIV has increased the incidence of tuberculosis (TB) by up to sevenfold in African countries, but antiretroviral therapy (ART) reduces the incidence of AIDS-related TB. We use a mathematical model to investigate the short-term and long-term impacts of ART on the incidence of TB, assuming that people are tested for HIV once a year, on average, and start ART at a fixed time after HIV seroconversion or at a fixed CD4(+) cell count. We fit the model to trend data on HIV prevalence and TB incidence in nine countries in sub-Saharan Africa. If HIV-positive people start ART within 5 y of seroconversion, the incidence of AIDS-related TB in 2015 will be reduced by 48% (range: 37-55%). Long-term reductions depend sensitively on the delay to starting ART. If treatment is started 5, 2, or 1 y after HIV seroconversion, or as soon as people test positive, the incidence in 2050 will be reduced by 66% (range: 57-80%), 95% (range: 93-96%), 97.7% (range: 96.9-98.2%) and 98.4% (range: 97.8-98.9%), respectively. In the countries considered here, early ART could avert 0.71 ± 0.36 [95% confidence interval (CI)] million of 3.4 million cases of TB between 2010 and 2015 and 5.8 ± 2.9 (95% CI) million of 15 million cases between 2015 and 2050. As more countries provide ART at higher CD4(+) cell counts, the impact on TB should be investigated to test the predictions of this model.

Will circumcision provide even more protection from HIV to women and men? New estimates of the population impact of circumcision interventions

BACKGROUND

Mathematical modelling has indicated that expansion of male circumcision services in high HIV prevalence settings can substantially reduce population-level HIV transmission. However, these projections need revision to incorporate new data on the effect of male circumcision on the risk of acquiring and transmitting HIV.

METHODS

Recent data on the effect of male circumcision during wound healing and the risk of HIV transmission to women were synthesised based on four trials of circumcision among adults and new observational data of HIV transmission rates in stable partnerships from men circumcised at younger ages. New estimates were generated for the impact of circumcision interventions in two mathematical models, representing the HIV epidemics in Zimbabwe and Kisumu, Kenya. The models did not capture the interaction between circumcision, HIV and other sexually transmitted infections.

RESULTS

An increase in the risk of HIV acquisition and transmission during wound healing is unlikely to have a major impact of circumcision interventions. However, it was estimated that circumcision confers a 46% reduction in the rate of male-to-female HIV transmission. If this reduction begins 2 years after the procedure, the impact of circumcision is substantially enhanced and accelerated compared with previous projections with no such effect-increasing by 40% the infections averted by the intervention overall and doubling the number of infections averted among women.

CONCLUSIONS

Communities, and especially women, may benefit much more from circumcision interventions than had previously been predicted, and these results provide an even greater imperative to increase scale-up of safe male circumcision services.

Postexposure prophylaxis, preexposure prophylaxis or universal test and treat: the strategic use of antiretroviral drugs to prevent HIV acquisition and transmission

This review considers the use of antiretroviral drugs specifically to prevent HIV transmission. Antiretroviral therapy (ART) can be implemented for the protection of uninfected individuals both before (preexposure prophylaxis) and after (postexposure prophylaxis) exposure to HIV infection. Preexposure prophylaxis may be used coitally dependently when individuals are intermittently exposed or by continuous daily dosing for those constantly exposed; postexposure prophylaxis is used in 28-day courses. Alternatively, ART can be used strategically to reduce the viral load and consequent infectiousness of an HIV-infected individual, thereby limiting the risk of onward viral transmission. A policy of universal HIV testing to enhance the identification of all HIV-positive individuals followed by immediate treatment of all HIV-positive individuals, irrespective of their CD4 cell counts (universal test and treat), has been postulated as a potential tool capable of reducing HIV incidence at a population level. This concept represents a paradigm shift in the use of ART, targeting infectious individuals for prevention rather than protecting uninfected exposed populations. This strategy could have the advantage of preventing transmission and reducing HIV incidence at a population level, as well as delivering universal access to therapy for all people living with HIV and AIDS, potentially eliminating mother-to-child HIV transmission and limiting concomitant diseases such as tuberculosis. This review critically examines the scientific basis of ART for HIV prevention, summarizing the risks and opportunities of the potential expansion of ART for prevention. Specifically, we consider the evidences for and against targeting HIV-uninfected individuals compared with enhanced HIV testing and treatment of HIV-infected individuals in terms of impact on viral transmission.

HIV prevention research: taking stock and the way forward

Previous papers in this supplement have reviewed the evidence of the effectiveness of alternative HIV prevention methods from randomized controlled trials and other studies. This paper draws together the main conclusions from these reviews. A conceptual framework is presented that maps the proximal and distal determinants of sexual HIV transmission and helps to identify the stages in the causal pathway at which each intervention approach acts. The advances, gaps and challenges emerging from the reviews of individual intervention methods are summarized and cross-cutting themes identified. Approximately 90% of HIV prevention trials have found no effect on HIV incidence and we explore the alternative explanations for the large number of 'flat' trials. We conclude that there is no single explanation for these flat results, which may be due to interventions that are ineffective or inappropriately targeted or implemented, or to factors related to the design or conduct of trials. We examine the lessons from these flat results and provide recommendations on what should be done differently in future trials. HIV prevention remains of critical importance in an era of expanded delivery of antiretroviral therapy. In future HIV prevention research, it is important that resources are used as efficiently as possible to provide rigorous evidence of the effectiveness of a wider array of complementary prevention tools.

Antiretroviral treatment of primary HIV infection to reduce onward transmission

PURPOSE OF REVIEW

This review will discuss the role of antiretroviral therapy to treat primary HIV infection (PHI) as a strategy to prevent onward viral transmission.

RECENT FINDINGS

Novel technology has greatly enhanced the appreciation of the characteristics of recently transmitted HIV-1 variants. Recent primate data demonstrate marked enhanced infectiousness of viral variants isolated from acutely infected macaques compared with viruses isolated from animals in the chronic phase of disease. These data are supported by phylogenetic analyses of recently transmitted cases in humans, implying that individuals with PHI may contribute disproportionately to onward transmission at a population level.

SUMMARY

In the absence of randomized clinical trial data supporting individual benefit of antiretroviral therapy, targeting and treating individuals with PHI as a public health intervention strategy represent a paradigm shift from current treatment strategies based around proven individual benefit alone. However, there is increasing evidence that PHI contributes disproportionately to viral transmission at a population level and failure to incorporate the potential role PHI plays, particularly in focused epidemics, maybe a naïve omission of many of the current mathematical models evaluating the impact of universal test and treat on population-level HIV incidence.

Rethinking prevention of HIV type 1 infection

Research on the prevention of human immunodeficiency virus (HIV)-1 infection is at a critical juncture. Major methodological challenges to performing prevention trials have emerged, and one after another promising biomedical interventions have failed to reduce the incidence of HIV-1 infection. Nevertheless, there is growing optimism that progress can be achieved in the near term. Mathematical modeling indicates that 2 new strategies, "test and treat" and preexposure prophylaxis, could have a major impact on the incidence of HIV-1 infection. Will our hopes be justified? We review the potential strengths and limitations of these antiretroviral "treatment as prevention" strategies and outline other new options for reducing the incidence of HIV-1 infection in the near term. By maximizing the potential of existing interventions, developing other effective strategies, and combining them in an optimal manner, we have the opportunity to bring the HIV-1 epidemic under control.

Highly active antiretroviral treatment as prevention of HIV transmission: review of scientific evidence and update

PURPOSE OF REVIEW

An estimated 33 million people are living with HIV and universal access remains a dream for millions of people. By the end of year 2008, four million people were on treatment; however, over five million needed treatment, and in 2007, there were 2.7 million new infections. Without significant improvement in prevention, we are unlikely to meet universal access targets including the growing demand for highly active antiretroviral treatment (HAART). This review examines HAART as a potential tool for preventing HIV transmission.

RECENT FINDINGS

We discuss recent scientific evidence regarding the treatment and prevention gap, importance viral load and HIV transmission, HAART and HIV transmission, when to start, HIV counseling and testing, modeling results and next steps.

SUMMARY

HAART has considerable treatment and prevention benefits and it needs to be considered as a key element of combination prevention. To explore HAART as an effective prevention strategy, we recommend further evaluation of human rights and ethical considerations, clarification of research priorities and exploration of feasibility and acceptability issues.

Modelling sexual transmission of HIV: testing the assumptions, validating the predictions

PURPOSE OF REVIEW

To discuss the role of mathematical models of sexual transmission of HIV: the methods used and their impact.

RECENT FINDINGS

We use mathematical modelling of 'universal test and treat' as a case study to illustrate wider issues relevant to all modelling of sexual HIV transmission.

SUMMARY

Mathematical models are used extensively in HIV epidemiology to deduce the logical conclusions arising from one or more sets of assumptions. Simple models lead to broad qualitative understanding, whereas complex models can encode more realistic assumptions and, thus, be used for predictive or operational purposes. An overreliance on model analysis in which assumptions are untested and input parameters cannot be estimated should be avoided. Simple models providing bold assertions have provided compelling arguments in recent public health policy, but may not adequately reflect the uncertainty inherent in the analysis.

How HIV treatment could result in effective prevention

As the number of HIV infections continues to surpass treatment capacity, new HIV prevention strategies are imperative. Beyond individual clinical benefits, by rendering an individual less infectious, expanding access to highly active antiretroviral therapy (HAART) could also have a larger public health impact of curbing new HIV infections. Recent guidelines have moved towards initiating HAART at higher CD4 cell counts, thus increasing the number of individuals in need of treatment. A new treatment strategy is wanting that can simultaneously curb the epidemic and provide necessary treatment to those most in need. A recent debate has centered on whether an expansion of free and universal treatment, regardless of CD4 cell count, could be a means of HIV prevention. In light of the growing access to HAART in resource-limited settings and increasing evidence suggesting the clinical and prevention benefits of initiating treatment at higher CD4 cell counts, it is conceivable that, in the future, HAART will be an integral part of both individual-level clinical treatment programs as well as public health-based HIV prevention interventions.

A decline in new HIV infections in South Africa: estimating HIV incidence from three national HIV surveys in 2002, 2005 and 2008

BACKGROUND

Three national HIV household surveys were conducted in South Africa, in 2002, 2005 and 2008. A novelty of the 2008 survey was the addition of serological testing to ascertain antiretroviral treatment (ART) use.

METHODS AND PRINCIPAL FINDINGS

We used a validated mathematical method to estimate the rate of new HIV infections (HIV incidence) in South Africa using nationally representative HIV prevalence data collected in 2002, 2005 and 2008. The observed HIV prevalence levels in 2008 were adjusted for the effect of antiretroviral treatment on survival. The estimated "excess" HIV prevalence due to ART in 2008 was highest among women 25 years and older and among men 30 years and older. In the period 2002-2005, the HIV incidence rate among men and women aged 15-49 years was estimated to be 2.0 new infections each year per 100 susceptible individuals (/100pyar) (uncertainty range: 1.2-3.0/100pyar). The highest incidence rate was among 15-24 year-old women, at 5.5/100pyar (4.5-6.5). In the period 2005-2008, incidence among men and women aged 15-49 was estimated to be 1.3/100 (0.6-2.5/100pyar), although the change from 2002-2005 was not statistically significant. However, the incidence rate among young women aged 15-24 declined by 60% in the same period, to 2.2/100pyar, and this change was statistically significant. There is evidence from the surveys of significant increases in condom use and awareness of HIV status, especially among youth.

CONCLUSIONS

Our analysis demonstrates how serial measures of HIV prevalence obtained in population-based surveys can be used to estimate national HIV incidence rates. We also show the need to determine the impact of ART on observed HIV prevalence levels. The estimation of HIV incidence and ART exposure is crucial to disentangle the concurrent impact of prevention and treatment programs on HIV prevalence.