Can male circumcision have an impact on the HIV epidemic in men who have sex with men?

Modeling the impact of different PrEP targeting strategies combined with a clinic-based HIV-1 nucleic acid testing intervention in Kenya

BACKGROUND

Up to 69% of adults who acquire HIV in Kenya seek care for acute retroviral symptoms, providing an important opportunity for early diagnosis and HIV care engagement. The Tambua Mapema Plus (TMP) trial tested a combined HIV-1 nucleic acid testing, linkage, treatment, and partner notification intervention for adults with symptoms of acute HIV infection presenting to health facilities in coastal Kenya. We estimated the potential impact on the Kenyan HIV epidemic of providing PrEP to individuals testing negative in TMP, if scaled up.

METHODS

We developed an agent-based simulation of HIV-1 transmission using TMP data and current Kenyan statistics. PrEP interventions were layered onto a model of TMP as standard of care, to estimate additional potential population-level impact of enrolling HIV-negative individuals identified through TMP on PrEP over 10 years. Four scenarios were modeled: PrEP for uninfected individuals in disclosed serodiscordant couples; PrEP for individuals with concurrent partnerships; PrEP for all uninfected individuals identified through TMP; and PrEP integrated into the enhanced partner services component of TMP.

FINDINGS

Providing PrEP to both individuals with concurrent partnerships and uninfected partners identified through enhanced partner services reduced new HIV infections and was efficient based on numbers needed to treat (NNT). The mean percent of infections averted was 2.79 (95%SI:-10.83, 15.24) and 4.62 (95%SI:-9.5, 16.82) when PrEP uptake was 50% and 100%, respectively, and median NNT was 22.54 (95%SI:not defined, 6.45) and 27.55 (95%SI:not defined, 11.0), respectively. Providing PrEP for all uninfected individuals identified through TMP averted up to 12.68% (95%SI:0.17, 25.19) of new infections but was not efficient based on the NNT: 200.24 (95%SI:523.81, 123.23).

CONCLUSIONS

Providing PrEP to individuals testing negative for HIV-1 nucleic acid after presenting to a health facility with symptoms compatible with acute HIV adds value to the TMP intervention, provided PrEP is targeted effectively and efficiently.

FUNDING

National Institutes of Health, Sub-Saharan African Network for TB/HIV Research Excellence.

Does Voluntary Medical Male Circumcision Reduce HIV Risk in Men Who Have Sex with Men?

PURPOSE OF REVIEW

To review the evidence on the effect of voluntary medical male circumcision (VMMC) on reducing HIV risk among men who have sex with men (MSM) and assess the limitations of available evidence.

RECENT FINDINGS

Individual studies have shown conflicting results, but recent meta-analyses have consistently suggested that VMMC was associated with 7 to 23% reductions in HIV prevalence or incidence in MSM, particularly among a subgroup of men who predominantly practice insertive role in anal sex. Mathematical models have also suggested a moderate population-level impact of VMMC intervention. All original studies have been observational and are subject to confounding and bias. Randomized clinical trials (RCTs) are needed to provide strong evidence of assessing the efficacy of VMMC on HIV risk among MSM. VMMC is a promising HIV risk reduction tool for MSM. RCTs are needed to evaluate the efficacy of VMMC intervention.

Agent-based model projections for reducing HIV infection among MSM: Prevention and care pathways to end the HIV epidemic in Chicago, Illinois

Our objective is to improve local decision-making for strategies to end the HIV epidemic using the newly developed Levers of HIV agent-based model (ABM). Agent-based models use computer simulations that incorporate heterogeneity in individual behaviors and interactions, allow emergence of systemic behaviors, and extrapolate into the future. The Levers of HIV model (LHM) uses Chicago neighborhood demographics, data on sex-risk behaviors and sexual networks, and data on the prevention and care cascades, to model local dynamics. It models the impact of changes in local preexposure prophylaxis (PrEP) and antiretroviral treatment (ART) (ie, levers) for meeting Illinois' goal of "Getting to Zero" (GTZ) -reducing by 90% new HIV infections among men who have sex with men (MSM) by 2030. We simulate a 15-year period (2016-2030) for 2304 distinct scenarios based on 6 levers related to HIV treatment and prevention: (1) linkage to PrEP for those testing negative, (2) linkage to ART for those living with HIV, (3) adherence to PrEP, (4) viral suppression by means of ART, (5) PrEP retention, and (6) ART retention. Using tree-based methods, we identify the best scenarios at achieving a 90% HIV infection reduction by 2030. The optimal scenario consisted of the highest levels of ART retention and PrEP adherence, next to highest levels of PrEP retention, and moderate levels of PrEP linkage, achieved 90% reduction by 2030 in 58% of simulations. We used Bayesian posterior predictive distributions based on our simulated results to determine the likelihood of attaining 90% HIV infection reduction using the most recent Chicago Department of Public Health surveillance data and found that projections of the current rate of decline (2016-2019) would not achieve the 90% (p = 0.0006) reduction target for 2030. Our results suggest that increases are needed at all steps of the PrEP cascade, combined with increases in retention in HIV care, to approach 90% reduction in new HIV diagnoses by 2030. These findings show how simulation modeling with local data can guide policy makers to identify and invest in efficient care models to achieve long-term local goals of ending the HIV epidemic.

Modeling the Impact of HIV-1 Nucleic Acid Testing Among Symptomatic Adult Outpatients in Kenya

BACKGROUND

Up to 69% of adults who acquire HIV in Kenya seek care before seroconversion, providing an important opportunity for early diagnosis and treatment. The Tambua Mapema Plus (TMP) trial tested a combined HIV-1 nucleic acid testing, linkage, treatment, and partner notification intervention for adults aged 18-39 years with symptoms of acute HIV infection presenting to health facilities in coastal Kenya. We estimated the potential impact of TMP on the Kenyan HIV epidemic.

METHODS

We developed an agent-based network model of HIV-1 transmission using TMP data and Kenyan statistics to estimate potential population-level impact of targeted facility-based testing over 10 years. Three scenarios were modeled: standard care [current use of provider-initiated testing and counseling (PITC)], standard HIV rapid testing scaled to higher coverage obtained in TMP (scaled-up PITC), and the TMP intervention.

RESULTS

Standard care resulted in 90.7% of persons living with HIV (PLWH) knowing their status, with 67.5% of those diagnosed on treatment. Scaled-up PITC resulted in 94.4% of PLWH knowing their status and 70.4% of those diagnosed on treatment. The TMP intervention achieved 97.5% of PLWH knowing their status and 80.6% of those diagnosed on treatment. The percentage of infections averted was 1.0% (95% simulation intervals: -19.2% to 19.9%) for scaled-up PITC and 9.4% (95% simulation intervals: -8.1% to 24.5%) for TMP.

CONCLUSION

Our study suggests that leveraging new technologies to identify acute HIV infection among symptomatic outpatients is superior to scaled-up PITC in this population, resulting in >95% knowledge of HIV status, and would reduce new HIV infections in Kenya.

Human immunodeficiency virus prevention strategies in China

This paper reviews the current epidemics of human immunodeficiency virus (HIV) infection in China, particularly the globally available prevention strategies developed and implemented. This review focuses on HIV prevention measures in general, such as education, testing, and counseling and in specific responses to transmission modes, such as blood safety, harm reduction for people who inject drugs, and condom promotion to reduce sexual transmission. We also assess newly developed prevention measures, such as prevention treatment, pre-exposure prophylaxis, post-exposure prophylaxis, male circumcision, and promising potential future preventions, including microbicides and vaccines. Based on this assessment, we provide recommendations for their implementation in China. We conclude that there is no magic bullet for HIV prevention, particularly sexual transmission of the disease, but only a combination of these prevention strategies can control the HIV epidemic.

Leveraging Modularity During Replication of High-Fidelity Models: Lessons from Replicating an Agent-Based Model for HIV Prevention

High-fidelity models are increasingly used to predict, and guide decision making. Prior work has emphasized the importance of replication in ensuring reliable modeling, and has yielded important replication strategies. However, this work is based on relatively simple theory generating models, and its lessons might not translate to high-fidelity models used for decision support. Using NetLogo we replicate a recently published high-fidelity model examining the effects of a HIV biomedical intervention. We use a modular approach to build our model from the ground up, and provide examples of the replication process investigating the replication of two sub-modules as well as the overall simulation experiment. For the first module, we achieved numerical identity during replication, whereas we obtained distributional equivalence in replicating the second module. We achieved relational equivalence among the overall model behaviors, with a 0.98 correlation across the two implementations for our outcome measure even without strictly following the original model in the formation of the sexual network. Our results show that replication of high-fidelity models is feasible when following a set of systematic strategies that leverage the modularity, and highlight the role of replication standards, modular testing, and functional code in facilitating such strategies.

Circumcision to prevent HIV and other sexually transmitted infections in men who have sex with men: a systematic review and meta-analysis of global data

BACKGROUND

Men who have sex with men (MSM) are disproportionately affected by HIV and other sexually transmitted infections (STIs) worldwide. Previous reviews investigating the role of circumcision in preventing HIV and other STIs among MSM were inconclusive. Many new studies have emerged in the past decade. To inform global prevention strategies for HIV and other STIs among MSM, we reviewed all available evidence on the associations between circumcision and HIV and other STIs among MSM.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Web of Science, BioMed Central, Scopus, ResearchGate, Cochrane Library, Embase, PsycINFO, Google Scholar, and websites of international HIV and STI conferences for studies published before March 8, 2018. Interventional or observational studies containing original quantitative data describing associations between circumcision and incident or prevalent infection of HIV and other STIs among MSM were included. Studies were excluded if MSM could not be distinguished from men who have sex with women only. We calculated pooled odds ratios (ORs) and their 95% CIs using random-effect models. We assessed risk of bias using the Newcastle-Ottawa scale.

FINDINGS

We identified 62 observational studies including 119 248 MSM. Circumcision was associated with 23% reduced odds of HIV infection among MSM overall (OR 0·77, 95% CI 0·67-0·89; number of estimates [k]=45; heterogeneity I²=77%). Circumcision was protective against HIV infection among MSM in countries of low and middle income (0·58, 0·41-0·83; k=23; I²=77%) but not among MSM in high-income countries (0·99, 0·90-1·09; k=20; I²=40%). Circumcision was associated with reduced odds of herpes simplex virus (HSV) infection among MSM overall (0·84, 0·75-0·95; k=5; I²=0%) and penile human papillomavirus (HPV) infection among HIV-infected MSM (0·71, 0·51-0·99; k=3; I²=0%).

INTERPRETATION

We found evidence that circumcision is likely to protect MSM from HIV infection, particularly in countries of low and middle income. Circumcision might also protect MSM from HSV and penile HPV infection. MSM should be included in campaigns promoting circumcision among men in countries of low and middle income. In view of the substantial proportion of MSM in countries of low and middle income who also have sex with women, well designed longitudinal studies differentiating MSM only and bisexual men are needed to clarify the effect of circumcision on male-to-male transmission of HIV and other STIs.

FUNDING

National Natural Science Foundation of China, National Science and Technology Major Project of China, Australian National Health and Medical Research Council Early Career Fellowship, Sanming Project of Medicine in Shenzhen, National Institutes of Health, Mega Projects of National Science Research for the 13th Five-Year Plan, Doris Duke Charitable Foundation.

Predicting the long-term impact of voluntary medical male circumcision on HIV incidence among men who have sex with men in Beijing, China

Using a deterministic compartmental modeling procedure to fit prevalence from 2005-2015, we projected new HIV cases during 2016-2026 under different coverage rates ranging from 0.0001 (at baseline) to 0.15 (an optimistic assumption) with simulations on varying transmission rates, model calibration to match historical data, and sensitivity analyses for different assumptions. Compared with the baseline (λ = 0.0001), we found the new HIV cases would reduce with the increase of coverage rates of the voluntary medical male circumcision (VMMC) among men who have sex wtih men (MSM). The higher the coverage rate, the lower the new HIV incidence would be. As one of the first studies to model the potential impact of VMMC among MSM in China, our model suggested a modest to the significant public health impact of VMMC. Even at just 15% VMMC annual uptake rate, the reduction in new infections is substantial. Therefore, there is a strong need to determine the efficacy of VMMC among MSM, to improve the evidence base for its potential use among MSM in low circumcision settings. Only then can policymakers decide whether to incorporate VMMC into a package of HIV prevention interventions targeting MSM.

Sexual network characteristics of men who have sex with men with syphilis and/or gonorrhoea/chlamydia in Lima, Peru: network patterns as roadmaps for STI prevention interventions

OBJECTIVE

While men who have sex with men (MSM) are disproportionately affected by Peru's overlapping HIV and STI epidemics, there are few data on how partnership-level and network-level factors affect STI transmission in Peru. We explored partnership-level and network-level factors associated with gonorrhoea/chlamydia (Neisseria gonorrhoeae and/or Chlamydia trachomatis (NG/CT)) and/or syphilis infection among MSM in Peru.

METHODS

We present the results of a cross-sectional secondary analysis of MSM (n=898) tested for syphilis and NG/CT infection as part of the screening process for two STI control trials in Lima, Peru. Participants completed questionnaires on demographics, sexual identity and role, characteristics of their three most recent sexual partners (partner sexual orientation, gender, role, partnership type, partner-specific sexual acts) and 30-day sexual network characteristics (number of sexual partners, partnership types, frequency of anal/vaginal intercourse). Participants were tested for syphilis and urethral, rectal and oropharyngeal NG/CT. Differences in network characteristics were analysed with χ2 and Kruskal-Wallis tests.

RESULTS

Approximately 38.9% of participants had a new STI diagnosis (syphilis (rapid plasma reagin ≥16): 10.6%; NG/CT: 22.9%; syphilis-NG/CT coinfection: 5.4%). Condomless anal intercourse (CAI) was not significantly associated with an STI diagnosis. Gay-identified participants with exclusively homosexual networks had a higher prevalence of STIs (47.4%) than gay-identified MSM with only heterosexual/bisexual partners (34.6%, p=0.04), despite reporting fewer sexual partners (any partners: 2, 1-4 vs 3, 2-6; p=0.001; casual partners: 1, 0-3 vs 2, 1-4; p=0.001) and more stable partnerships (1, 0-1 vs 0, 0-1; p=0.003) in the last month.

CONCLUSIONS

Network size and the number of casual sexual partners were associated with NG/CT infection among MSM in Peru. Despite reporting fewer sexual risk behaviours (smaller network size, more stable partnerships, less CAI), MSM with homosexual-only sexual networks had a higher prevalence of NG/CT and syphilis. These findings suggest network composition among MSM in Peru plays an important role in the risk for STI acquisition.

Modeling economic and epidemiological impact of voluntary medical male circumcision among men who have sex with men in Beijing, China

Voluntary medical male circumcision (VMMC) among men who have sex with men (MSM) may protect against HIV acquisition. We conducted a series of analyses to assess if expanded VMMC might reduce HIV incidence among MSM effectively and economically. We used a deterministic compartmental model to project new HIV cases (2016-2026) under annual VMMC coverage rates (λ) ranging from 0.0001 to 0.15. The 'number needed to avert' (NNA) is defined as the cumulative number of VMMCs conducted up to that year divided by the cumulative number of HIV cases averted in that specific year. Compared with the baseline circumcision coverage rate, we projected that new HIV cases would be reduced with increasing coverage. By 2026 (last year simulated), the model generated the lowest ratio (11.10) when the annual circumcision rate was the most optimistic (λ = 0.15). The breakeven point was observed at the year of 2019 with the annual VMMC coverage rate of 0.001. The total cost saved by averting HIV cases would range from 2.5 to 811 million US dollars by the end of 2026 with different hypothetical coverage rates. Our model suggests that acceleration in VMMC implementation among MSM could help stem the HIV/AIDS epidemic.

Development of an Agent-Based Model to Investigate the Impact of HIV Self-Testing Programs on Men Who Have Sex With Men in Atlanta and Seattle

BACKGROUND

In the United States HIV epidemic, men who have sex with men (MSM) remain the most profoundly affected group. Prevention science is increasingly being organized around HIV testing as a launch point into an HIV prevention continuum for MSM who are not living with HIV and into an HIV care continuum for MSM who are living with HIV. An increasing HIV testing frequency among MSM might decrease future HIV infections by linking men who are living with HIV to antiretroviral care, resulting in viral suppression. Distributing HIV self-test (HIVST) kits is a strategy aimed at increasing HIV testing. Our previous modeling work suggests that the impact of HIV self-tests on transmission dynamics will depend not only on the frequency of tests and testers' behaviors but also on the epidemiological and testing characteristics of the population.

OBJECTIVE

The objective of our study was to develop an agent-based model to inform public health strategies for promoting safe and effective HIV self-tests to decrease the HIV incidence among MSM in Atlanta, GA, and Seattle, WA, cities representing profoundly different epidemiological settings.

METHODS

We adapted and extended a network- and agent-based stochastic simulation model of HIV transmission dynamics that was developed and parameterized to investigate racial disparities in HIV prevalence among MSM in Atlanta. The extension comprised several activities: adding a new set of model parameters for Seattle MSM; adding new parameters for tester types (ie, regular, risk-based, opportunistic-only, or never testers); adding parameters for simplified pre-exposure prophylaxis uptake following negative results for HIV tests; and developing a conceptual framework for the ways in which the provision of HIV self-tests might change testing behaviors. We derived city-specific parameters from previous cohort and cross-sectional studies on MSM in Atlanta and Seattle. Each simulated population comprised 10,000 MSM and targeted HIV prevalences are equivalent to 28% and 11% in Atlanta and Seattle, respectively.

RESULTS

Previous studies provided sufficient data to estimate the model parameters representing nuanced HIV testing patterns and HIV self-test distribution. We calibrated the models to simulate the epidemics representing Atlanta and Seattle, including matching the expected stable HIV prevalence. The revised model facilitated the estimation of changes in 10-year HIV incidence based on counterfactual scenarios of HIV self-test distribution strategies and their impact on testing behaviors.

CONCLUSIONS

We demonstrated that the extension of an existing agent-based HIV transmission model was sufficient to simulate the HIV epidemics among MSM in Atlanta and Seattle, to accommodate a more nuanced depiction of HIV testing behaviors than previous models, and to serve as a platform to investigate how HIV self-tests might impact testing and HIV transmission patterns among MSM in Atlanta and Seattle. In our future studies, we will use the model to test how different HIV self-test distribution strategies might affect HIV incidence among MSM.

Incidence of Gonorrhea and Chlamydia Following Human Immunodeficiency Virus Preexposure Prophylaxis Among Men Who Have Sex With Men: A Modeling Study

Background

Preexposure prophylaxis (PrEP) is highly effective for preventing human immunodeficiency virus (HIV) infection, but risk compensation (RC) in men who have sex with men (MSM) raises concerns about increased sexually transmitted infections (STIs). The Center for Disease Control and Prevention's (CDC's) PrEP guidelines recommend biannual STI screening, which may reduce incidence by treating STIs that would otherwise remain undiagnosed. We investigated these two counteracting phenomena.

Methods

With a network-based mathematical model of HIV, Neisseria gonorrhoeae (NG), and Chlamydia trachomatis (CT) transmission dynamics among MSM in the United States, we simulated PrEP uptake following the prescription indications and HIV/STI screening recommendations in the CDC guidelines. Scenarios varied PrEP coverage (the proportion of MSM indicated for PrEP who received it), RC (a reduction in the per-act probability of condom use), and the STI screening interval.

Results

In our reference scenario (40% coverage, 40% RC), 42% of NG and 40% of CT infections would be averted over the next decade. A doubling of RC would still result in net STI prevention relative to no PrEP. STIs declined because PrEP-related STI screening resulted in a 17% and 16% absolute increase in the treatment of asymptomatic and rectal STIs, respectively. Screening and timely treatment at quarterly vs biannual intervals would reduce STI incidence an additional 50%.

Conclusions

Implementation of the CDC PrEP guidelines while scaling up PrEP coverage could result in a significant decline in STI incidence among MSM. Our study highlights the design of PrEP not only as antiretroviral medication but as combination HIV/STI prevention incorporating STI screening.

Attitudes, Beliefs and Predictors of Male Circumcision Promotion among Medical University Students in a Traditionally Non-Circumcising Region

Objective: To evaluate the beliefs of medical university students regarding male circumcision (MC), as well as attitudes and the predictors of its promotion in the case of adults at risk of HIV. Methods: A cross-sectional survey was conducted between 2013-2016 at the Medical University in Szczecin, Poland, among final year Polish/foreign students from Northern Europe, using a standardized questionnaire. Results: There were 539 participants, median age 25 years, 40.8% males, and 66.8% were Polish nationals. The MC rate was 16.7%. Regarding HIV/AIDS knowledge, 66.6% of the students scored more than 75%; and, 34.2% knew that MC reduces the risk of HIV infection. One in eleven respondents (9.1%) believed that circumcised men felt more intense sexual pleasure. More than half of the respondents (54.8%) declared that they would recommend MC to adult patients at risk for HIV. The belief that circumcised men felt more intense sexual pleasure, and knowledge on MC regarding HIV risk reduction was associated with greater odds of recommending adult MC (OR = 3.35 and OR = 2.13, respectively). Conclusions: Poor knowledge of its benefits and a low willingness to promote the procedure-strongly dependent on personal beliefs-suggest that medical students may need additional training to help them to discuss MC more openly with adult men at risk for HIV infection. Knowledge may be an effective tool when making decisions regarding MC promotion.

The Impact of Preexposure Prophylaxis Among Men Who Have Sex With Men: An Individual-Based Model

OBJECTIVES

Preexposure prophylaxis (PrEP) is recommended for preventing HIV infection among individuals at high risk, including men who have sex with men (MSM). Although its individual-level efficacy is proven, questions remain regarding population-level impact of PrEP implementation.

DESIGN

We developed an agent-based simulation of HIV transmission among MSM, accounting for demographics, sexual contact network, HIV disease stage, and use of antiretroviral therapy. We use this framework to compare PrEP delivery strategies in terms of impact on HIV incidence and prevalence.

RESULTS

The projected reduction in HIV incidence achievable with PrEP reflects both population-level coverage and individual-level adherence (as a proportion of days protected against HIV transmission). For example, provision of PrEP to 40% of HIV-negative MSM reporting more than one sexual partner in the last 12 months, taken with sufficient adherence to provide protection on 40% of days, can reduce HIV incidence by 9.5% (95% uncertainty range: 8%-11%) within 5 years. However, if this could be increased to 80% coverage on 80% of days (eg, through mass campaigns with a long-acting injectable formulation), a 43% (42%-44%) reduction in HIV incidence could be achieved. Delivering PrEP to MSM at high risk for HIV acquisition can augment population-level impact up to 1.8-fold.

CONCLUSIONS

If highly ambitious targets for coverage and adherence can be achieved, PrEP can substantially reduce HIV incidence in the short-term. Although the reduction in HIV incidence largely reflects the proportion of person-years protected, the efficiency of PrEP delivery can be enhanced by targeting high-risk populations.

'We go to the bush to prove that we are also men': traditional circumcision and masculinity in the accounts of men who have sex with men in township communities in South Africa

In predominantly isiXhosa-speaking township communities in South Africa, men who have sex with men negotiate their identities and sexual practices alongside heteronormative cultural scripts of what it means to be a man. Such idealised notions of masculinity are predicated on the selective appropriation of cultural practices that preserve (heterosexual) male privilege and power. In this paper, we explore the identity work done by men who have sex with men, with particular reference to male circumcision as a cultural practice widely drawn on to inform and regulate normative masculinity. Through a narrative-discursive analysis of the accounts provided by men who have sex with men from township communities, we highlight how participants' dissident sexualities are constructed as compromising their masculine identities. Participating in cultural practices such as traditional circumcision aligns participants to the idealised forms of masculinity that afford men full citizenship in their communities. Study findings suggest that sexual dissidence is less troubling to participants than deviating from gendered markers of hegemonic masculinity, and point to ways in which marginalised men might have an interest in maintaining the dominant gendered order. We conclude with implications for research and programmatic work with gay, bisexual and other men who have sex with men.

Impact of the Centers for Disease Control's HIV Preexposure Prophylaxis Guidelines for Men Who Have Sex With Men in the United States

BACKGROUND

 Preexposure prophylaxis (PrEP) is effective for preventing human immunodeficiency virus (HIV) infection among men who have sex with men (MSM) within trial settings. Population impact will depend on clinical indications for PrEP initiation, coverage levels, and drug adherence. No modeling studies have estimated the impact of clinical practice guidelines for PrEP issued by the Centers for Disease Control and Prevention (CDC).

METHODS

 Mathematical models of HIV transmission among MSM were used to estimate the percentage of infections averted (PIA) and the number needed to treat (NNT) under behavioral indications of the CDC's PrEP guidelines. We modeled the contribution of these indications while varying treatment coverage and adherence.

RESULTS

 At 40% coverage of indicated MSM over the next decade, application of CDC guidelines would avert 1162 infections per 100 000 person-years, 33.0% of expected infections. The predicted NNT for the guidelines would be 25. Increasing coverage and adherence jointly raise the PIA, but reductions to the NNT were associated with better adherence only.

CONCLUSIONS

 Implementation of CDC PrEP guidelines would result in strong and sustained reductions in HIV incidence among MSM in the United States. The guidelines strike a good balance between epidemiological impact (PIA) and efficiency (NNT) at plausible scale-up levels. Adherence counseling could maximize public health investment in PrEP by decreasing the NNT.

Lower HIV Risk Among Circumcised Men Who Have Sex With Men in China: Interaction With Anal Sex Role in a Cross-Sectional Study

BACKGROUND

Voluntary medical male circumcision reduces the risk of HIV heterosexual transmission in men, but its effect on male-to-male sexual transmission is uncertain.

METHODS

Circumcision status of men who have sex with men (MSM) in China was evaluated by genital examination and self-report; anal sexual role was assessed by questionnaire interview. Serostatus for HIV and syphilis was confirmed.

RESULTS

Among 1155 participants (242 were seropositive and 913 with unknown HIV status at enrollment), the circumcision rate by self-report (10.4%) was higher than confirmed by genital examination (8.2%). Male circumcision (by examination) was associated with 47% lower odds of being HIV seropositive [adjusted odds ratio (aOR): 0.53; 95% confidence interval (CI): 0.27 to 1.02] after adjusting for demographic covariates, number of lifetime male sexual partners, and anal sex role. Among MSM who predominantly practiced insertive anal sex, circumcised men had 62% lower odds of HIV infection than those who were uncircumcised (aOR: 0.38; 95% CI: 0.09 to 1.64). Among those whose anal sex position was predominantly receptive or versatile, circumcised men have 46% lower odds of HIV infection than did men who were not circumcised (aOR: 0.54; 95% CI: 0.25 to 1.14). Compared to uncircumcised men reporting versatile or predominantly receptive anal sex positioning, those who were circumcised and reported practicing insertive sex had an 85% lower risk (aOR: 0.15; 95% CI: 0.04 to 0.65). Circumcision was not associated clearly with lower syphilis risk (aOR: 0.91; 95% CI: 0.51 to 1.61).

CONCLUSIONS

Circumcised MSM were less likely to have acquired HIV, most pronounced among men predominantly practicing insertive anal intercourse. A clinical trial is needed.

HIV infection

More than 75 million people worldwide have been infected with human immunodeficiency virus (HIV), and there are now approximately 37 million individuals living with the infection. Untreated HIV replication causes progressive CD4(+) T cell loss and a wide range of immunological abnormalities, leading to an increased risk of infectious and oncological complications. HIV infection also contributes to cardiovascular disease, bone disease, renal and hepatic dysfunction and several other common morbidities. Antiretroviral drugs are highly effective at inhibiting HIV replication, and for individuals who can access and adhere to these drugs, combination antiretroviral therapy leads to durable (and probably lifelong) suppression of viral replication. Viral suppression enables immune recovery and the near elimination of the risk for developing acquired immune deficiency syndrome (AIDS). Despite effective treatment, HIV-infected individuals have a higher than expected risk of heart, bone, liver, kidney and neurological disease. When used optimally by an infected (or by an uninfected) person, antiretroviral drugs can virtually eliminate the risk of HIV transmission. Despite major advances in prevention sciences, HIV transmission remains common in many vulnerable populations, including men who have sex with men, injection drug users and sex workers. Owing to a lack of widespread HIV testing and the costs and toxicities associated with antiretroviral drugs, the majority of the infected population is not on effective antiretroviral therapy. To reverse the pandemic, improved prevention, treatment and implementation approaches are necessary.

Combination HIV prevention among MSM in South Africa: results from agent-based modeling

HIV prevention trials have demonstrated the effectiveness of a number of behavioral and biomedical interventions. HIV prevention packages are combinations of interventions and offer potential to significantly increase the effectiveness of any single intervention. Estimates of the effectiveness of prevention packages are important for guiding the development of prevention strategies and for characterizing effect sizes before embarking on large scale trials. Unfortunately, most research to date has focused on testing single interventions rather than HIV prevention packages. Here we report the results from agent-based modeling of the effectiveness of HIV prevention packages for men who have sex with men (MSM) in South Africa. We consider packages consisting of four components: antiretroviral therapy for HIV infected persons with CD4 count <350; PrEP for high risk uninfected persons; behavioral interventions to reduce rates of unprotected anal intercourse (UAI); and campaigns to increase HIV testing. We considered 163 HIV prevention packages corresponding to different intensity levels of the four components. We performed 2252 simulation runs of our agent-based model to evaluate those packages. We found that a four component package consisting of a 15% reduction in the rate of UAI, 50% PrEP coverage of high risk uninfected persons, 50% reduction in persons who never test for HIV, and 50% ART coverage over and above persons already receiving ART at baseline, could prevent 33.9% of infections over 5 years (95% confidence interval, 31.5, 36.3). The package components with the largest incremental prevention effects were UAI reduction and PrEP coverage. The impact of increased HIV testing was magnified in the presence of PrEP. We find that HIV prevention packages that include both behavioral and biomedical components can in combination prevent significant numbers of infections with levels of coverage, acceptance and adherence that are potentially achievable among MSM in South Africa.