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

PrEP in the Context of Other HIV Risk Reduction Strategies Among Men Who Have Sex with Men: Results from the Flash! PrEP in Europe Survey

Combination HIV prevention covers a range of biomedical, behavioral, and socio-structural interventions. Despite the growing availability of pre-exposure prophylaxis (PrEP), it is not always accessible in European Centre for Disease Prevention and Control reporting countries and may not meet the needs of all at-risk populations. Based on the Flash! PrEP in Europe data, multiple correspondence analysis and hierarchical clustering were used to identify patterns in HIV prevention strategies among 9980 men who have sex with men (MSM). PrEP interest was evaluated among four identified clusters: (A) "high condom use, sometimes Treatment as Prevention (TasP)"; (B) "mix of methods, infrequent condom use"; (C) "high condom use, tendency to choose partners based on serological status" and (D) "moderate use of condoms mixed with other prevention strategies". Clusters B and D had higher PrEP interest. These results suggest that MSM use a range of behavioral and biomedical risk reduction strategies that are often combined. On-demand PrEP may meet the needs of MSM who infrequently use condoms and other prevention methods.

Key policies and measures of HIV/AIDS prevention and control at global level

During the last 40 years, the development of medical HIV and AIDS related knowledge has been followed by a coordinated international HIV response, in terms of developing policies and measures for the HIV/AIDS prevention and control based on evidence from public health and clinical studies. The HIV response can be divided into three periods: the period of HIV response establishment (1981-1996); the period of multi-sectoral response (1996-2007) and the period of strengthening biomedical measures for HIV prevention (2007 and beyond). International policies and recommended HIV prevention measures have undergone a series of transformations, from the establishment of the first organized and coordinated national programs, to the design and implementation of innovative biomedical prevention measures, such as voluntary medical circumcision, pre-exposure prophylaxis and the implementation of the "test and treat" measure - the introduction of antiretroviral therapy immediately after diagnosing HIV infection to achieve undetectable viral load. New findings on successful use of antiretroviral therapy as prevention led to the formulation of goals for 2020: 90% of all people living with HIV to know their HIV status, 90% of them to receive antiretroviral therapy, and 90% of them to have viral suppression; to have less than 500 000 of both newly HIV infected persons, and AIDS related deaths. Despite of the HIV response major improvements, such as development and implementation of multisectoral national HIV/AIDS policies on prevention and control, the 2020 goals have not been meet. For achieving the main goal - ending AIDS as public health threat by 2030 - implementation of all recommended biomedical, behavioral and structural interventions should be intensified.

Hepatitis B virus seroepidemiology data for Africa: Modelling intervention strategies based on a systematic review and meta-analysis

BACKGROUND

International Sustainable Development Goals (SDGs) for elimination of hepatitis B virus (HBV) infection set ambitious targets for 2030. In African populations, infant immunisation has been fundamental to reducing incident infections in children, but overall population prevalence of chronic hepatitis B (CHB) infection remains high. In high-prevalence populations, adult catch-up vaccination has sometimes been deployed, but an alternative Test and Treat (T&T) approach could be used as an intervention to interrupt transmission. Universal T&T has not been previously evaluated as a population intervention for HBV infection, despite high-profile data supporting its success with human immunodeficiency virus (HIV).

METHODS AND FINDINGS

We set out to investigate the relationship between prevalence of HBV infection and exposure in Africa, undertaking a systematic literature review in November 2019. We identified published seroepidemiology data representing the period 1995-2019 from PubMed and Web of Science, including studies of adults that reported prevalence of both hepatitis B surface antigen (HBsAg; prevalence of HBV infection) and antibody to hepatitis B core antigen (anti-HBc; prevalence of HBV exposure). We identified 96 studies representing 39 African countries, with a median cohort size of 370 participants and a median participant age of 34 years. Using weighted linear regression analysis, we found a strong relationship between the prevalence of infection (HBsAg) and exposure (anti-HBc) (R2 = 0.45, p < 0.001). Region-specific differences were present, with estimated CHB prevalence in Northern Africa typically 30% to 40% lower (p = 0.007) than in Southern Africa for statistically similar exposure rates, demonstrating the need for intervention strategies to be tailored to individual settings. We applied a previously published mathematical model to investigate the effect of interventions in a high-prevalence setting. The most marked and sustained impact was projected with a T&T strategy, with a predicted reduction of 33% prevalence by 20 years (95% CI 30%-37%) and 62% at 50 years (95% CI 57%-68%), followed by routine neonatal vaccination and prevention of mother to child transmission (PMTCT; at 100% coverage). In contrast, the impact of catch-up vaccination in adults had a negligible and transient effect on population prevalence. The study is constrained by gaps in the published data, such that we could not model the impact of antiviral therapy based on stratification by specific clinical criteria and our model framework does not include explicit age-specific or risk-group assumptions regarding force of transmission.

CONCLUSIONS

The unique data set collected in this study highlights how regional epidemiology data for HBV can provide insights into patterns of transmission, and it provides an evidence base for future quantitative research into the most effective local interventions. In combination with robust neonatal immunisation programmes, ongoing PMTCT efforts, and the vaccination of high-risk groups, diagnosing and treating HBV infection is likely to be of most impact in driving advances towards elimination targets at a population level.

Microbicides for topical immunoprevention of HIV infection

Microbicides are antiseptic topical drugs that help directly or indirectly inhibit the penetration of an infectious agent into the human body, thereby preventing the sexual transmission of HIV-infection and other sexually transmitted diseases. Microbicides have an antiviral mechanism of action in the sexual transmission of HIV and affect the components of mucosal immunity in the vagina. In this article, the pharmaceutical and biomedical aspects of microbicide application are examined and diverse classifications of microbicides are presented. For each group of chemicals, the most important representatives and their mechanisms of action are described. This article also presents the structure and function of mucosal immunity, and shows the importance of the mucosal immune response in the sexual transmission of HIV. This work also exhibits the experimental models for testing of candidate microbicides. For each compound described, a review of preclinical research and clinical trials is provided, covering its development as a microbicide. This paper gives an overview of microbicides, a new class of chemically diverse immunobiological medications reducing the risk of sexual transmission of HIV. The use of microbicides is believed to curb the HIV/AIDS epidemic in the nearest future.

The informal use of antiretroviral medications for HIV prevention by men who have sex with men in South Florida: initiation, use practices, medications and motivations

Limited data suggest that some gay and other men who have sex with men are using antiretroviral medications informally, without a prescription, for HIV prevention. This qualitative study examined this phenomenon among gay and other men who have sex with men in South Florida. Participants initiated informal antiretroviral medication use as a means of protecting each other and because of the confidence in knowledge of antiretroviral medications shared by their friends and sex partners. The most commonly used medications included Truvada and Stribild. Motivations for use included condom avoidance, risk reduction, and fear of recent HIV exposure. Participants described positive and negative sentiments related to informal use, including concerns about informal antiretroviral medications offering sufficient protection against HIV, and limited knowledge about pre-exposure prophylaxis (PrEP). Because the antiretroviral medications used for PrEP have the potential to prevent HIV infection, future research must consider the informal antiretroviral medication use and related concerns, including adherence, diversion and viral resistance.

Cross-feeding modulates antibiotic tolerance in bacterial communities

Microbes frequently rely on metabolites excreted by other bacterial species, but little is known about how this cross-feeding influences the effect of antibiotics. We hypothesized that when species rely on each other for essential metabolites, the minimum inhibitory concentration (MIC) for all species will drop to that of the “weakest link”—the species least resistant in monoculture. We tested this hypothesis in an obligate cross-feeding system that was engineered between Escherichia coli, Salmonella enterica, and Methylobacterium extorquens. The effect of tetracycline and ampicillin were tested on both liquid and solid media. In all cases, resistant species were inhibited at significantly lower antibiotic concentrations in the cross-feeding community than in monoculture or a competitive community. However, deviation from the “weakest link” hypothesis was also observed in cross-feeding communities apparently as result of changes in the timing of growth and cross-protection. Comparable results were also observed in a clinically relevant system involving facultative cross-feeding between Pseudomonas aeruginosa and an anaerobic consortium found in the lungs of cystic fibrosis patients. P. aeruginosa was inhibited by lower concentrations of ampicillin when cross-feeding than when grown in isolation. These results suggest that cross-feeding significantly alters tolerance to antibiotics in a variety of systems.

Changing temporal trends in non-AIDS cancer mortality among people diagnosed with AIDS: San Francisco, California, 1996-2013

BACKGROUND

Antiretroviral therapy (ART) has reduced AIDS-defining cancer (ADC) mortality, but its effect on non-AIDS-defining cancer (NADC) mortality is unclear. To help inform cancer prevention and screening, we evaluated trends in NADC mortality among people with AIDS (PWA) in the ART era.

METHODS

This retrospective cohort study analyzed AIDS surveillance data, including causes of death from death certificates, for PWA in San Francisco who died in 1996-2013. Proportional mortality ratios (PMRs), and year, age, race, sex-adjusted standardized mortality ratios (SMRs) were calculated for 1996-1999, 2000-2005, and 2006-2013, corresponding to advances in ART.

RESULTS

The study included 5822 deceased PWA of whom 90% were male and 68% were aged 35-54 at time of death. Over time, the PMRs significantly decreased for ADCs (2.6%, 1.4%, 1.2%) and increased for NADCs (4.3%, 7.0%, 12.3%). For all years combined (1996-2013) and compared to the California population, significantly elevated SMRs were observed for these cancers: all NADCs combined (2.1), anal (58.4), Hodgkin lymphoma (10.5), liver (5.2), lung/larynx (3.0), rectal (5.2), and tongue (4.7). Over time, the SMRs for liver cancer (SMR 19.8, 11.2, 5.0) significantly decreased while the SMRs remained significantly elevated over population levels for anal (SMR 123, 48.2, 45.5), liver (SMR 19.8, 11.2, 5.0), and lung/larynx cancer (SMR 5.3, 4.7, 3.6).

CONCLUSION

A decline in ADC PMRs and increase in NADC PMRs represent a shift in the cancer burden, likely due to ART use. Moreover, given their elevated SMRs, anal, liver, and lung/larynx cancer remain targets for improved cancer prevention, screening, and treatment.

Beyond Condoms: Risk Reduction Strategies Among Gay, Bisexual, and Other Men Who Have Sex With Men Receiving Rapid HIV Testing in Montreal, Canada

Gay, bisexual, and other men who have sex with men (MSM) have adapted their sexual practices over the course of the HIV/AIDS epidemic based on available data and knowledge about HIV. This study sought to identify and compare patterns in condom use among gay, bisexual, and other MSM who were tested for HIV at a community-based testing site in Montreal, Canada. Results showed that while study participants use condoms to a certain extent with HIV-positive partners and partners of unknown HIV status, they also make use of various other strategies such as adjusting to a partner's presumed or known HIV status and viral load, avoiding certain types of partners, taking PEP, and getting tested for HIV. These findings suggest that MSM who use condoms less systematically are not necessarily taking fewer precautions but may instead be combining or replacing condom use with other approaches to risk reduction.

Cost effectiveness of 'on demand' HIV pre-exposure prophylaxis for non-injection drug-using men who have sex with men in Canada

BACKGROUND

Recent trials report the efficacy of continuous tenofovir-based pre-exposure prophylaxis (PrEP) for prevention of HIV infection. The cost effectiveness of 'on demand' PrEP for non-injection drug-using men who have sex with men at high risk of HIV acquisition has not been evaluated.

OBJECTIVE

To conduct an economic evaluation of the societal costs of HIV in Canada and evaluate the potential benefits of this PrEP strategy.

METHODS

Direct HIV costs comprised outpatient, inpatient and emergency department costs, psychosocial costs and antiretroviral costs. Resource consumption estimates were derived from the Centre Hospitalier de l'Université de Montréal HIV cohort. Estimates of indirect costs included employment rate and work absenteeism. Costs for 'on demand' PrEP were modelled after an ongoing clinical trial. Cost-effectiveness analysis compared costs of 'on demand' PrEP to prevent one infection with lifetime costs of one HIV infection. Benefits were presented in terms of life-years and quality-adjusted life-years.

RESULTS

The average annual direct cost of one HIV infection was $16,109 in the least expensive antiretroviral regimen scenario and $24,056 in the most expensive scenario. The total indirect cost was $11,550 per year. Total costs for the first year of HIV infection ranged from $27,410 to $35,358. Undiscounted lifetime costs ranged from $1,439,984 ($662,295 discounted at 3% and $448,901 at 5%) to $1,482,502 ($690,075 at 3% and $485,806 at 5%). The annual cost of PrEP was $12,001 per participant, and $621,390 per infection prevented. The PrEP strategy was cost-saving in all scenarios for undiscounted and 3% discounting rates. At 5% discounting rates, the strategy is largely cost-effective: according to least and most expensive scenarios, incremental cost-effectiveness ratios ranged from $60,311 to $47,407 per quality-adjusted life-year.

CONCLUSION

This 'on demand' PrEP strategy ranges from cost-saving to largely cost-effective. The authors believe it represents an important public health strategy for the prevention of HIV transmission.

Dual quantification of dapivirine and maraviroc in cervicovaginal secretions from ophthalmic tear strips and polyester-based swabs via liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis

BACKGROUND

Topical microbicidal agents are being actively pursued as a modality to prevent HIV viral transmission during sexual intercourse. Quantification of antiretroviral agents in specimen sources where antiviral activity is elicited is critical, and drug measurements in cervicovaginal fluid can provide key information on local drug concentrations. Two antiretroviral drugs, dapivirine and maraviroc, have gained interest as vaginal microbicidal agents, and rugged methods are required for their quantification in cervicovaginal secretions.

METHODS

Cervicovaginal fluid spiked with dapivirine and maraviroc were applied to ophthalmic tear strips or polyester-based swabs to mimic collection procedures used in clinical studies. Following sample extraction and the addition of isotopically labeled internal standards, samples were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis using a Waters BEH C8, 50mm×2.1mm, 1.7μm particle size column, on an API 4000 mass analyzer operated in selective reaction monitoring mode. The method was validated according to FDA Bioanalytical Method Validation guidelines.

RESULTS

Due to the disparate saturation capacity of the tested collection devices, the analytical measuring ranges for dapivirine and maravirocin cervicovaginal fluid on the ophthalmic tear strip were 0.05-25ng/tear strip, and 0.025-25ng/tear strip, respectively. As for the polyester-based swab, the analytical measuring ranges were 0.25-125ng/swab for dapivirine and 0.125-125ng/swab for maraviroc. Dilutional studies were performed for both analytes to extended ranges of 25,000ng/tear strip and 11,250ng/swab. Standard curves were generated via weighted (1/x(2)) linear or quadratic regression of calibrators. Precision, accuracy, stability and matrix effects studies were all performed and deemed acceptable according to the recommendations of the FDA Bioanalytical Method Validation guidelines.

CONCLUSIONS

A rugged LC-MS/MS method for the dual quantification of dapivirine and maraviroc in cervicovaginal fluid using two unique collection devices has been developed and validated. The described method meets the criteria to support large research trials.

The development and validation of an UHPLC-MS/MS method for the rapid quantification of the antiretroviral agent dapivirine in human plasma

BACKGROUND

Dapivirine is a non-nucleoside reverse transcriptase inhibitor designed to prevent HIV-1 viral replication and subsequent propagation. A sensitive method is required to quantify plasma concentrations to assess drug efficacy.

RESULTS

Dapivirine-spiked plasma was combined with acetonitrile containing deuterated IS and was processed for analysis. The method has an analytical measuring range from 20 to 10,000 pg/ml. For the LLOQ, low, mid and high QCs, intra- and inter-assay precision (%CV) ranged from 5.58 to 13.89% and 5.23 to 13.36%, respectively, and intra- and inter-day accuracy (% deviation) ranged from -5.61 to 0.75% and -4.30 to 6.24%, respectively.

CONCLUSION

A robust and sensitive LC-MS/MS assay for the high-throughput quantification of the antiretroviral drug dapivirine in human plasma was developed and validated following bioanalytical validation guidelines. The assay meets criteria for the analysis of samples from large research trials.

The development and validation of a method using high-resolution mass spectrometry (HRMS) for the qualitative detection of antiretroviral agents in human blood

BACKGROUND

Antiretroviral drugs are used for the treatment and prevention of HIV infection. Non-adherence to antiretroviral drug regimens can compromise their clinical efficacy and lead to emergence of drug-resistant HIV. Clinical trials evaluating antiretroviral regimens for HIV treatment and prevention can also be compromised by poor adherence and non-disclosed off-study antiretroviral drug use. This report describes the development and validation of a high throughput, qualitative method for the identification of antiretroviral drugs using high-resolution mass spectrometry (HRMS) for the retrospective assessment of off-study antiretroviral drug use and the determination of potential antiretroviral therapy (ART) non-compliance.

METHODS

Serum standards were prepared that contained 15 antiretroviral drugs: 9 protease inhibitors (PIs), 4 nucleotide/nucleoside reverse transcriptase inhibitors (NRTIs), and 2 non-nucleoside/nucleotide reverse transcriptase inhibitors (NNRTIs). Analytical separation was achieved on a Hypersil Gold PFP (100×3mm) column and the eluent was analyzed using the Thermo Exactive Orbitrap mass spectrometer (Exactive-MS) operated in full scan mode. Limit of identification, signal intensity precision, retention time analysis, selectivity, and carryover studies were conducted. Concordance with liquid chromatographic-tandem mass spectrometric (LC-MS/MS) methods was evaluated using remnant plasma samples from a clinical trial.

RESULTS

The limit of identification ranged from 5 to 10ng/ml for 14 drugs (9 PIs, 1 NNRTI, 4 NRTIs) and was 150ng/ml for 1 NNRTI. Precision studies with high and low control mixtures revealed signal intensity coefficients of variation of 3.0-27.5%. The Exactive-MS method was selective for the compounds of interest. Overall, concordance ranged from 89.1% to 100% for the screening of antiretroviral drugs in clinical plasma specimens as compared to LC-MS/MS methods.

CONCLUSION

Using the Exactive-MS, we developed and validated a highly selective, robust method for the multiplexed detection of 15 antiretroviral drugs.

HIV-1 genetic characteristics and transmitted drug resistance among men who have sex with men in Kunming, China

BACKGROUND

Yunnan has been severely affected by HIV/AIDS in China. Recently, the reported prevalence of HIV-1 among men who have sex with men (MSM) in Yunnan was high in China. To monitor dynamic HIV-1 epidemic among Yunnan MSM, HIV-1 genetic characteristics and transmitted drug resistance (TDR) were investigated.

METHODS

Blood samples from 131 newly HIV-1 diagnosed MSM were continuously collected at fixed sites from January 2010 to December 2012 in Kunming City, Yunnan Province. Partial gag, pol and env genes were sequenced. Phylogenetic, evolutionary and genotypic drug resistance analyses were performed.

RESULTS

Multiple genotypes were identified among MSM in Kunming, including CRF01_AE (64.9%), CRF07_BC (25.2%), unique recombinant forms (URFs, 5.3%), subtype B (3.1%) and CRF08_BC (1.5%). CRF01_AE and CRF07_BC were the predominant strains. The mean of genetic distance within CRF01_AE were larger than that within CRF07_BC. The estimated introducing time of CRF01_AE in Yunnan MSM (1996.9) is earlier than that of CRF07_BC (2002.8). In this study, subtype B was first identified in Yunnan MSM. CRF08_BC seems to be the distinctive strain in Yunnan MSM, which was seldom found among MSM outside Yunnan. The proportion of URFs increased, which further contributed to genetic diversity among MSM. Strikingly, genetic relatedness was found among these strains with MSM isolates from multiple provinces, which suggested that a nationwide transmission network may exist. TDR-associated mutations were identified in 4.6% individuals. The multivariate analysis revealed that non-native MSM and divorced/widowed MSM were independently associated with a higher TDR rate.

CONCLUSION

This work revealed diverse HIV-1 genetics, national transmission networks and a baseline level of TDR in MSM. These findings enhance our understanding of the distribution and evolution of HIV-1 in MSM, and are valuable for developing HIV prevention strategies for MSM.

Nondisclosure of HIV status in a clinical trial setting: antiretroviral drug screening can help distinguish between newly diagnosed and previously diagnosed HIV infection

In The HIV Prevention Trials Network 061 study, 155 human immunodeficiency virus (HIV)-infected men reported no prior HIV diagnosis; 83 of those men had HIV RNA levels of <1000 copies/mL at enrollment. Antiretroviral drug testing revealed that 65 of the 83 (78.3%) men were on antiretroviral treatment. Antiretroviral drug testing can help distinguish between newly diagnosed and previously diagnosed HIV infection.

Vulnerable infected populations and street markets for ARVs: Potential implications for PrEP rollout in the USA

Widespread diversion of antiretroviral (ARV) medications to illicit markets has recently been documented among indigent patients in South Florida. The recent approval of ARVs for pre-exposure prophylaxis (PrEP) has the potential to broaden these illicit markets, as high-risk individuals seek ARVs without a prescription or medical supervision. Nonadherence among diverters and unsupervised use of ARVs for treatment or PrEP increase risks of treatment failure, drug resistance, and disease transmission. We report the scope of ARV diversion among substance-using men who have sex with men in South Florida. Structured interviews (N = 515) queried demographics, HIV status, mental distress, substance dependence, and sexual risks. HIV-positive participants answered questions about medical care, treatment, and ARV adherence and diversion. Median age was 39. Of 46.4% who were HIV-positive, 79.1% were prescribed ARVs. Of these, 27% reported selling/trading ARVs. Reasons for diversion were sharing/trading with friends, sale/trade for money/drugs, and sale/trade of unused medications. ARV diverters, compared to nondiverters, were more likely to be substance dependent (74.5% vs. 58.7%, p = 0.046) and have traded sex for money/drugs (60.8% vs. 32.6%, p < 0.001), and less likely to be adherent to ARVs (54.9% vs. 73.9%, p = 0.012). ARV diversion should be a particular concern in communities of high-risk men who have sex with men as uninfected men in such communities are likely to benefit most from PrEP but unlikely to have access to PrEP and necessary ancillary services through the health-care system. The implications of diversion for increased risks of treatment failure, disease transmission, and PrEP failure should be carefully considered in developing policy and behavioral supports to scaling up treatment as prevention and PrEP.

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.

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

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

[Consensus document of Gesida and Spanish Secretariat for the National Plan on AIDS (SPNS) regarding combined antiretroviral treatment in adults infected by the human immunodeficiency virus (January 2012)]

This consensus document has been prepared by a panel consisting of members of the AIDS Study Group (Gesida) and the Spanish Secretariat for the National Plan on AIDS (SPNS) after reviewing the efficacy and safety results of clinical trials, cohort and pharmacokinetic studies published in medical journals, or presented in medical scientific meetings. Gesida has prepared an objective and structured method to prioritise combined antiretroviral treatment (cART) in naïve patients. Recommendations strength (A, B, C) and the evidence which supports them (I, II, III) are based on a modification of the Infectious Diseases Society of America criteria. The current antiretroviral treatment (ART) of choice for chronic HIV infection is the combination of three drugs. ART is recommended in patients with symptomatic HIV infection, in pregnancy, in serodiscordant couples with high transmission risk, hepatitis B fulfilling treatment criteria, and HIV nephropathy. Guidelines on ART treatment in patients with concurrent diagnosis of HIV infection and an opportunistic type C infection are included. In asymptomatic patients ART is recommended on the basis of CD4 lymphocyte counts, plasma viral load and patient co-morbidities, as follows: 1) therapy should be started in patients with CD4 counts <350 cells/μL; 2) when CD4 counts are between 350 and 500 cells/μL, therapy will be recommended and only delayed if patient is reluctant to take it, the CD4 are stabilised, and the plasma viral load is low; 3) therapy could be deferred when CD4 counts are above 500 cells/μL, but should be considered in cases of cirrhosis, chronic hepatitis C, high cardiovascular risk, plasma viral load >10(5) copies/mL, proportion of CD4 cells <14%, and in people aged >55 years. ART should include 2 reverse transcriptase inhibitors nucleoside analogues and a third drug (non-analogue reverse transcriptase inhibitor, ritonavir boosted protease inhibitor or integrase inhibitor). The panel has consensually selected and given priority to using the Gesida score for some drug combinations, some of them co-formulated. The objective of ART is to achieve an undetectable viral load. Adherence to therapy plays an essential role in maintaining antiviral response. Therapeutic options are limited after ART failures, but an undetectable viral load may be possible nowadays. Adverse events are a fading problem of ART. Guidelines in acute HIV infection, in women, in pregnancy, and to prevent mother-to-child transmission and pre- and post-exposition prophylaxis are commented upon. Management of hepatitis B or C co-infection, other co-morbidities, and the characteristics of ART in HIV-2 infection are included.

Beyond virological suppression: the role of adherence in the late HAART era

HAART has increased the life expectancy of HIV-infected individuals significantly. Optimal adherence to HAART results in viral suppression and immune recovery in the majority of HIV-infected persons. Data from the early HAART era suggest that adherence levels of greater than 95% are necessary to achieve and maintain virological suppression. However, the optimal threshold of adherence required to maximize the pharmacological benefits of contemporary antiretroviral regimens, particularly in the virologically suppressed patient, is unknown. This review examines new data on the role of adherence in the late HAART era, focusing on virological, immunological and epidemiological aspects. We begin with a discussion of the impact of adherence on viral dynamics and immunological parameters in the virologically suppressed patient. We then review the importance of adherence in emerging antiretroviral treatment strategies. Finally, we summarize accumulating data on the role of antiretroviral adherence in the prevention of HIV transmission. Taken together, the data reviewed reinforce the critical importance of adherence in the management of HIV infection in the late HAART era.

Paying for prevention: challenges to health insurance coverage for biomedical HIV prevention in the United States

Reducing the incidence of HIV infection continues to be a crucial public health priority in the United States, especially among populations at elevated risk such as men who have sex with men, transgender women, people who inject drugs, and racial and ethnic minority communities. Although most HIV prevention efforts to date have focused on changing risky behaviors, the past decade yielded efficacious new biomedical technologies designed to prevent infection, such as the prophylactic use of antiretroviral drugs and the first indications of an efficacious vaccine. Access to prevention technologies will be a significant part of the next decade's response to HIV and advocates are mobilizing to achieve more widespread use of these interventions. These breakthroughs, however, arrive at a time of escalating healthcare costs; health insurance coverage therefore raises pressing new questions about priority-setting and the allocation of responsibility for public health. The goals of this Article are to identify legal challenges and potential solutions for expanding access to biomedical HIV prevention through health insurance coverage. This Article discusses the public policy implications of HIVprevention coverage decisions, assesses possible legal grounds on which insurers may initially deny coverage for these technologies, and evaluates the extent to which these denials may survive external and judicial review. Because several of these legal grounds may be persuasive, particularly denials on the basis of medical necessity, this Article also explores alternative strategies for financing biomedical HIV prevention efforts.

Antiretroviral-based microbicides and oral pre-exposure prophylaxis for HIV prevention

Numerous HIV prevention options have been tested, with limited success. Microbicides have been the focus of research specifically targeted to prevent new infections among women. After decades of research using non-HIV-specific microbicides, we now have proof of concept for antiretroviral-based microbicides. Issues of drug resistance, frequency of HIV testing and adherence to treatment remain to be explored. Drugs used for HIV treatment and with good safety profiles have been shown to provide protection to men who have sex with men. Ethical issues surrounding cost, access, future design of HIV prevention trials and composition of the prevention package offered to trial participants remain. The role of advocacy and market research will be crucial to ensure effective interventions are accessed and supported. There is renewed hope in the HIV prevention field with collective efforts needed to ensure we get the new prevention tools and options into the hands of men and women at risk of HIV infection. The purpose of this paper is to provide a review of existing research and identify issues for future enquiry.

Targeting strategies and behavior change to combat the HIV epidemic in southern Africa

Behavior change remains a cornerstone of effective HIV prevention, whether interventions aim to reduce primary HIV acquisition or in the context of ‘prevention for positives’, the likelihood of onward transmission. However, to optimize the growing number of biomedical interventions, both prevention and implementation science will need to take a broader view of what they consider to be behavior change, move away from a narrow focus on risk behaviors and give greater consideration to health-seeking behaviors, social practices, cultural and social norms. These have been largely excluded from primary prevention thinking in southern Africa. Exciting developments in other areas of HIV research science, for example viral genetics, molecular and spatial epidemiology, can also be part of this process as they are able to help us to identify sub-populations at greatest risk, even in severe generalized epidemics. A number of biomedical interventions are already being rolled out, and attempts to bring them to scale will peak in the next few years. Much needs to be done to support these efforts, but equally much can be learned from the challenges that can have wider value in other resource-poor contexts. With better understanding and more accurate targeting of sub-populations, communities and behaviors, it will be possible to strengthen biomedical intervention strategies and improve allocation of prevention resources.

Advances in the prevention of heterosexual transmission of HIV/AIDS among women in the United States

Despite recent advances in testing and treatment, the incidence of HIV/AIDS in the United States has remained stagnant with an estimated 56,300 new infections every year. Women account for an increasing proportion of the epidemic. The vulnerability of women to HIV stems from both increased biologic susceptibility to heterosexual transmission and also the social, economic, and structural disadvantages they often confront. This review describes the main reasons for the increased vulnerability of U.S. women to HIV transmission with particular emphasis on specific highrisk groups including: non-Hispanic blacks, women who use drugs, women with a history of incarceration, and victims of intimate partner violence. Although behavioral approaches to HIV prevention may be effective, pragmatic implementation is often difficult, especially for women who lack sociocultural capital to negotiate condoms with their male partners. Recent advances in HIV prevention show promise in terms of female-initiated interventions. These notably include female condoms, non-specific vaginal microbicides, and antiretroviral oral and vaginal pre-exposure prophylaxis. In this review, we will present evidence in support of these new female-initiated interventions while also emphasizing the importance of advocacy and the political support for these scientific advances to be successful.

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.