Heterosexual risk of HIV-1 infection per sexual act: systematic review and meta-analysis of observational studies

Modeling the impact of a supervised consumption site on HIV and HCV transmission among people who inject drugs in three counties in California, USA

BACKGROUND

Supervised consumption sites (SCS) have been shown to reduce receptive syringe sharing among people who inject drugs (PWID) in the United States and elsewhere, which can prevent HIV and hepatitis C virus (HCV) transmission. PWID are at risk of disease transmission and may benefit from SCS, however legislation has yet to support their implementation. This study aims to determine the potential impact of SCS implementation on HIV and HCV incidence among PWID in three California counties.

METHODS

A dynamic HIV and HCV joint transmission model among PWID (sexual and injecting transmission of HIV, injecting transmission of HCV) was calibrated to epidemiological data for three counties: San Francisco, Los Angeles, and San Diego. The model incorporated HIV and HCV disease stages and HIV and HCV treatment. Based on United States data, we assumed access to SCS reduced receptive syringe sharing by a relative risk of 0.17 (95 % CI: 0.04-1.03). This model examined scaling-up SCS coverage from 0 % to 20 % of the PWID population within the respective counties and assessed its impact on HIV and HCV incidence rates after 10 years.

RESULTS

By increasing SCS from 0 % to 20 % coverage among PWID, 21.8 % (95 % CI: -1.2-32.9 %) of new HIV infections and 28.3 % (95 % CI: -2.0-34.5 %) of new HCV infections among PWID in San Francisco County, 17.7 % (95 % CI: -1.0-30.8 %) of new HIV infections and 29.8 % (95 % CI: -2.1-36.1 %) of new HCV infections in Los Angeles County, and 32.1 % (95 % CI: -2.8-41.5 %) of new HIV infections and 24.3 % (95 % CI: -1.6-29.0 %) of new HCV infections in San Diego County could be prevented over ten years.

CONCLUSION

Our models suggest that SCS is an important intervention to enable HCV elimination and could help end the HIV epidemic among PWID in California. It could also have additional benefits such facilitating pathways into drug treatment programs and preventing fatal overdose.

The impact of sex on HIV immunopathogenesis and therapeutic interventions

Globally, the majority of people living with HIV are women or girls, but they have been a minority of participants in clinical trials and observational studies of HIV. Despite this underrepresentation, differences in the pathogenesis of HIV have been observed between men and women, with contributions from both gender- and sex-based factors. These include differences in the risk of HIV acquisition, in viral load set point and immune activation in responses to viremia, and differences in HIV reservoir maintenance. These differences obligate adequate study in both males and females in order to optimize treatments, but also provide a powerful leverage point for delineating the mechanisms of HIV pathogenesis. The shifts in exposure to sex steroid hormones across a lifespan introduce additional complexity, which again can be used to focus on either genetic or hormonal influences as the driver of an outcome. In this Review, we discuss consistent and reproducible differences by sex across the spectrum of HIV, from acquisition through pathogenesis, treatment, and cure, and explore potential mechanisms and gaps in knowledge.

Development and calibration of a mathematical model of HIV outcomes among Rwandan adults: informing equitable achievement of targets in Rwanda

Background

We developed and calibrated the Central Africa-International epidemiology Databases to Evaluate AIDS (CA-IeDEA) HIV policy model to inform equitable achievement of global goals, overall and across sub-populations, in Rwanda.

Methods

We created a deterministic dynamic model to project adult HIV epidemic and care continuum outcomes, overall and for 25 subpopulations (age group, sex, HIV acquisition risk, urbanicity). Data came from the Rwanda cohort of CA-IeDEA, 2004-2020; Rwanda Demographic and Health Surveys, 2005, 2010, 2015; Rwanda Population-based HIV Impact Assessment, 2019; and the literature and reports. We calibrated the model to 47 targets by selecting the 50 best-fitting parameter sets among 20,000 simulations. Calibration targets reflected epidemic (HIV prevalence, incidence), global goals (percentage on antiretroviral therapy (ART) among diagnosed, percentage virally suppressed among on ART) and other (number on ART, percentage virally suppressed) indicators, overall and by sex. Best-fitting sets minimized the summed absolute value of the percentage deviation (AVPD) between model projections and calibration targets. Good model performance was mean AVPD ≤5% across the 50 best-fitting sets and/or projections within the target confidence intervals; acceptable was mean AVPD >5% and ≤15%.

Results

Across indicators, 1,841 of 2,350 (78.3%) model projections were a good or acceptable fit to calibration targets. For HIV epidemic indicators, 256 of 300 (85.3%) projections were a good fit to targets, with the model performing better for women (83.3% a good fit) than for men (71.7% a good fit). For global goals indicators, 96 of 100 (96.0%) projections were a good fit; model performance was similar for women and men. For other indicators, 653 of 950 (68.7%) projections were a good or acceptable fit. Fit was better for women than for men (percentage virally suppressed only) and when restricting targets for number on ART to 2013 and beyond.

Conclusions

The CA-IeDEA HIV policy model fits historical data and can inform policy solutions for equitably achieving global goals to end the HIV epidemic in Rwanda. High-quality, unbiased population-based data, as well as novel approaches that account for calibration target quality, are critical to ongoing use of mathematical models for programmatic planning.

Quantifying the impact of cascade inequalities: a modelling study on the prevention impacts of antiretroviral therapy scale-up in Eswatini

Background

Inequalities in the antiretroviral therapy (ART) cascade across subpopulations remain an ongoing challenge in the global HIV response. Eswatini achieved the UNAIDS 95-95-95 targets by 2020, with differentiated programs to minimize inequalities across subpopulations, including for female sex workers (FSW) and their clients. We sought to estimate additional HIV infections expected in Eswatini if cascade scale-up had not been equal, and under which epidemic conditions these inequalities could have the largest influence.

Methods

Drawing on population-level and FSW-specific surveys in Eswatini, we developed a compartmental model of heterosexual HIV transmission which included eight subpopulations and four sexual partnership types. We calibrated the model to stratified HIV prevalence, incidence, and ART cascade data. Taking observed cascade scale-up in Eswatini as the base-case-reaching 95-95-95 in the overall population by 2020-we defined four counterfactual scenarios in which the population overall reached 80-80-90 by 2020, but where FSW, clients, both, or neither were disproportionately left behind, reaching only 60-40-80. We quantified relative additional cumulative HIV infections by 2030 in counterfactual vs base-case scenarios. We further estimated linear effects of viral suppression gap among FSW and clients on additional infections by 2030, plus effect modification by FSW/client population sizes, rates of turnover, and HIV prevalence ratios.

Results

Compared with the base-case scenario, leaving behind neither FSW nor their clients led to the fewest additional infections by 2030: median (95% credible interval) 14.9 (10.4, 18.4)% vs 26.3 (19.7, 33.0)% if both were left behind-a 73 (40, 149)% increase. The effect of lower cascade on additional infections was larger for clients vs FSW, and both effects increased with population size and relative HIV incidence.

Conclusions

Inequalities in the ART cascade across subpopulations can undermine the anticipated prevention impacts of cascade scale-up. As Eswatini has shown, addressing inequalities in the ART cascade, particularly those that intersect with high transmission risk, could maximize incidence reductions from cascade scale-up.

MORTALITY RISK INFORMATION, SURVIVAL EXPECTATIONS AND SEXUAL BEHAVIOURS

We investigate the impact of a randomised information intervention about population-level mortality on health investment and subjective health expectations. Our focus is on risky sex in a high-HIV-prevalence environment. Treated individuals are less likely to engage in risky sexual practices one year after the intervention, with, for example, an 8% increase in abstinence. We collected detailed data on individuals' subjective expectations about their own and population survival, as well as other important health outcomes. Our findings emphasise the significance of integrating subjective expectation data in field experiments to identify the pathways that lead to behavioural change.

Can platform use patterns be an indicator of HIV-related risk and sub-group heterogeneity among men who have sex with men in Singapore: a latent class analysis

Introduction

Low-level HIV epidemic settings like Singapore face the challenge of reaching men at-risk who have less contact with programmes. We investigated patterns of meeting platform use by men seeking male sexual partners (MSM) as potential marker of risk to differentiate sub-groups for interventions.

Methods

Latent Class Analysis (LCA) was applied to a survey sample of MSM recruited from bars/clubs, saunas and a smartphone application, using purposive sampling. The best-fit LCA model which identified homogeneous sub-groups with similar patterns of meeting platform was factored in multivariable regression to identify associations with risk behaviors on the pathway to HIV infection.

Results

Overall 1,141 MSM were recruited from bars/clubs (n = 426), saunas (n = 531), and online (n = 184). Five patterns emerged, reflecting salient platform use characteristics: Sauna-centric (SC; n = 413), App-centric (AC; n = 276), Multiple-platforms (MP; n = 123), Platform-inactive (PI; n = 257), and "Do not hook up" (DNH; n = 72) classes. Men in the SC and MP classes had high probabilities of using saunas to meet partners; SC were older and less likely to have disclosed their sexual orientation. The MP class had high probabilities of connecting across all platforms in addition to saunas and more likely to have disclosed their sexual orientation, than the PI class. Men in the SC and MP classes had twice the odds of reporting multiple sex partners (aORSC = 2.1; 95%CI: 1.33.2; aORMP = 2.2; 95%CI: 1.14.6). Single/non-partnered MSM and those using alcohol/drugs during sex had 1.7 (95%CI: 1.22.5) and 3.2 (95%CI: 2.05.1) the odds respectively, of reporting multiple sex partners. The SC and MP classes had higher odds of engaging in group sex while MSM using alcohol/drugs during sex had twice the odds of reporting group sex. Alcohol/drugs and group sex were independently associated with condomless sex (as was lower education). Group sex, alcohol/drugs during sex, disclosure of sexual orientation or being Singaporean/permanent resident were associated with recent testing for HIV.

Discussion

The five distinct risk profiles identified can help tailor differentiated HIV interventions-combined with field knowledge and other prevention-to expand HIV self-testing, Pre-Exposure Prophylaxis and other services (e.g., Mpox vaccination) to sub-groups at risk.

Tenofovir Douche as HIV Preexposure Prophylaxis for Receptive Anal Intercourse: Safety, Acceptability, Pharmacokinetics, and Pharmacodynamics (DREAM 01)

BACKGROUND

Despite highly effective HIV preexposure prophylaxis (PrEP) options, no options provide on-demand, nonsystemic, behaviorally congruent PrEP that many desire. A tenofovir-medicated rectal douche before receptive anal intercourse may provide this option.

METHODS

Three tenofovir rectal douches-220 mg iso-osmolar product A, 660 mg iso-osmolar product B, and 660 mg hypo-osmolar product C-were studied in 21 HIV-negative men who have sex with men. We sampled blood and colorectal tissue to assess safety, acceptability, pharmacokinetics, and pharmacodynamics.

RESULTS

The douches had high acceptability without toxicity. Median plasma tenofovir peak concentrations for all products were several-fold below trough concentrations associated with oral tenofovir disoproxil fumarate (TDF). Median colon tissue mucosal mononuclear cell (MMC) tenofovir-diphosphate concentrations exceeded target concentrations from 1 hour through 3 to 7 days after dosing. For 6-7 days after a single product C dose, MMC tenofovir-diphosphate exceeded concentrations expected with steady-state oral TDF 300 mg on-demand 2-1-1 dosing. Compared to predrug baseline, HIV replication after ex vivo colon tissue HIV challenge demonstrated a concentration-response relationship with 1.9 log10 maximal effect.

CONCLUSIONS

All 3 tenofovir douches achieved tissue tenofovir-diphosphate concentrations and colorectal antiviral effect exceeding oral TDF and with lower systemic tenofovir. Tenofovir douches may provide a single-dose, on-demand, behaviorally congruent PrEP option, and warrant continued development. Clinical Trials Registration . NCT02750540.

Unravelling Delay in Care for Sexually Transmitted Infections-Related Symptoms in a Developing Country Setting (Jamaica)

BACKGROUND

Sexually transmitted infections (STIs) and STI treatment remain a challenge in public health. There is little understanding of related factors influencing health seeking behaviour and delay of care among clinic attendees in Jamaica.

AIM

To determine socio-demographic profile of clinic attendees with STI and identify factors associated with delay in seeking care for STI-related symptoms.

METHODS

A cross-sectional study was done. 201 adult patients presenting with STI symptoms from four health centres in Kingston and St Andrew were selected. A 24-item interviewer-assisted questionnaire was used to obtain data on socio-demographic characteristics, patients' symptoms and duration, previous STIs, knowledge of complications and seriousness of STIs, and factors influencing decision to seek medical care.

RESULTS

Almost 75% delayed seeking care for STIs. Recurrent STIs was identified in 41% of patients. 'Could not find time' was the most commonly reported reason for delay in seeking care (36%). Females were 3.4 times more likely to delay seeking care for STI symptoms than males (OR 3.42, 95% CI: 1.73-6.73). Those with primary level education and below were 5 times more likely to delay seeking care for STI symptoms than those with at least secondary level education (OR 5.05, 95% CI: 1.09-23.46). Participants viewed staff as confidential (68%) and 65% thought health-care workers spent adequate time during consultations.

CONCLUSION

Lower education level and the female gender are associated with delay in seeking care for STI-related symptoms. These factors should be considered when developing interventions to reduce delay in care for STI-related symptoms.

Role of HIV-1 Tat Protein Interactions with Host Receptors in HIV Infection and Pathogenesis

Each time the virus starts a new round of expression/replication, even under effective antiretroviral therapy (ART), the transactivator of viral transcription Tat is one of the first HIV-1 protein to be produced, as it is strictly required for HIV replication and spreading. At this stage, most of the Tat protein exits infected cells, accumulates in the extracellular matrix and exerts profound effects on both the virus and neighbor cells, mostly of the innate and adaptive immune systems. Through these effects, extracellular Tat contributes to the acquisition of infection, spreading and progression to AIDS in untreated patients, or to non-AIDS co-morbidities in ART-treated individuals, who experience inflammation and immune activation despite virus suppression. Here, we review the role of extracellular Tat in both the virus life cycle and on cells of the innate and adaptive immune system, and we provide epidemiological and experimental evidence of the importance of targeting Tat to block residual HIV expression and replication. Finally, we briefly review vaccine studies showing that a therapeutic Tat vaccine intensifies ART, while its inclusion in a preventative vaccine may blunt escape from neutralizing antibodies and block early events in HIV acquisition.

Comparison between a deep-learning and a pixel-based approach for the automated quantification of HIV target cells in foreskin tissue

The availability of target cells expressing the HIV receptors CD4 and CCR5 in genital tissue is a critical determinant of HIV susceptibility during sexual transmission. Quantification of immune cells in genital tissue is therefore an important outcome for studies on HIV susceptibility and prevention. Immunofluorescence microscopy allows for precise visualization of immune cells in mucosal tissues; however, this technique is limited in clinical studies by the lack of an accurate, unbiased, high-throughput image analysis method. Current pixel-based thresholding methods for cell counting struggle in tissue regions with high cell density and autofluorescence, both of which are common features in genital tissue. We describe a deep-learning approach using the publicly available StarDist method to count cells in immunofluorescence microscopy images of foreskin stained for nuclei, CD3, CD4, and CCR5. The accuracy of the model was comparable to manual counting (gold standard) and surpassed the capability of a previously described pixel-based cell counting method. We show that the performance of our deep-learning model is robust in tissue regions with high cell density and high autofluorescence. Moreover, we show that this deep-learning analysis method is both easy to implement and to adapt for the identification of other cell types in genital mucosal tissue.

Associations between forced non-consensual first-sex and HIV among sexually active women in the Kingdom of Eswatini

Studies continue to underscore the profound impact of sexual violence on women's health. Yet, little is known about the impact, via a complex matrix of behavioural and social factors, of first intercourse, namely forced non-consensual on HIV status, particularly among sexually active women (SAW) in low-income countries where HIV prevalence remains high. Using a national sample from Eswatini, we employed multivariate logistic regression modelling to estimate the associations between forced first-sex (FFS), subsequent sexual behaviour and HIV status among 3555 SAW aged from 15 years to 49 years. The results found that women who experienced FFS had a greater number of sexual partners compared to those who had never experienced FFS (aOR = 2.79, p < .01), although there were no significant differences in condom use, early sexual debut and casual sex involvement between these two groups. FFS remained significantly associated with a higher risk of having HIV (aOR = 1.70, p < .05) even after controlling for risky sexual behaviours and various other factors. These findings further reinforce the relationship between FFS and HIV, and suggest that addressing sexual violence is a critical component of HIV prevention among women in low-income countries.

The Association Between Heterosexual anal Intercourse and HIV Acquisition in Three Prospective Cohorts of Women

The extent to which receptive anal intercourse (RAI) increases the HIV acquisition risk of women compared to receptive vaginal intercourse (RVI) is poorly understood. We evaluated RAI practice over time and its association with HIV incidence during three prospective HIV cohorts of women: RV217, MTN-003 (VOICE), and HVTN 907. At baseline, 16% (RV 217), 18% (VOICE) of women reported RAI in the past 3 months and 27% (HVTN 907) in the past 6 months, with RAI declining during follow-up by around 3-fold. HIV incidence in the three cohorts was positively associated with reporting RAI at baseline, albeit not always significantly. The adjusted hazard rate ratios for potential confounders (aHR) were 1.1 (95% Confidence interval: 0.8-1.5) for VOICE and 3.3 (1.6-6.8) for RV 217, whereas the ratio of cumulative HIV incidence by RAI practice was 1.9 (0.6-6.0) for HVTN 907. For VOICE, the estimated magnitude of association increased slightly when using a time-varying RAI exposure definition (aHR = 1.2; 0.9-1.6), and for women reporting RAI at every follow-up survey (aHR = 2.0 (1.3-3.1)), though not for women reporting higher RAI frequency (> 30% acts being RAI vs. no RAI in the past 3 months; aHR = 0.7 (0.4-1.1)). Findings indicated precise estimation of the RAI/HIV association, following multiple RVI/RAI exposures, is sensitive to RAI exposure definition, which remain imperfectly measured. Information on RAI practices, RAI/RVI frequency, and condom use should be more systematically and precisely recorded and reported in studies looking at sexual behaviors and HIV seroconversions; standardized measures would aid comparability across geographies and over time.

Aging dysregulates neutrophil extracellular trap formation in response to HIV in blood and genital tissues

Women acquire HIV through sexual transmission, with increasing incidence in women >50 years old. Identifying protective mechanisms in the female genital tract (FGT) is important to prevent HIV-acquisition in women as they age. Human genital and blood neutrophils inactivate HIV by releasing neutrophil extracellular traps (NETs), an innate protective mechanism against HIV-infection. However, how NET formation is triggered by HIV in different tissues and whether this mechanism is affected by aging remain unknown. We demonstrate that the mechanisms that trigger NET release in response to HIV are different in blood and genital tissues, and that NET release decreases with aging. In blood neutrophils, HIV stimulation independently activated calcium pathways and endosomal TLR8, but aging reduced calcium responses, resulting in delayed NET release. In contrast, calcium responses were absent in genital neutrophils and NET release was triggered preferentially through TLR8 activation, but aging impaired this pathway. HIV induced NET formation through non-lytic pathways in blood and FGT neutrophils, except for a small subset of NETs that incorporated annexin V and lactoferrin predominantly in blood, suggesting proinflammatory and lytic NET release. Our findings demonstrate that blood neutrophils cannot model genital neutrophil responses which has important implications to understanding protection against HIV acquisition.

Transmission risk assessment of HIV/AIDS epidemic resulting from sexual transmission in China, 2013-2017

To estimate the risk of human immunodeficiency virus (HIV) infection through sexual transmission in China from 2013 to 2017 accurately, we divide the total population into three groups, namely, men who have sex with men (MSM) group; non-marital and commercial sex group: female sex workers (FSW) and their clients (FSWC); non-marital and non-commercial sex group: general women (GW) and general men (GM). First, the risks of HIV infection among men who have contacts with infected men or infected women decrease annually. Second, the number of contacts between susceptible FSWC and infected FSW per unit time is greater than that between susceptible MSM and infected MSM, and also greater than that between susceptible FSW and infected FSWC, which suggests that the intervention for commercial sex of heterosexual men should be strengthened. Third, the effective reproduction numbers of the MSM group and non-commercial sex group decrease annually, while the effective reproduction number of the commercial sex group decreases first, then increases, because the risk of women being infected by men decreases first, then increases. Additionally, the effective reproduction number of the commercial sex group exceeds that of the MSM group after 2015, which indicates that commercial sex contributes more and more to the HIV/AIDS epidemic.

Model-based predictions of protective HIV pre-exposure prophylaxis adherence levels in cisgender women

Most human immunodeficiency virus (HIV) infections occur in cisgender women in resource-limited settings. In women, self-protection with emtricitabine/tenofovir disoproxil fumarate pre-exposure prophylaxis (FTC/TDF-PrEP) constitutes a major pillar of HIV prevention. However, clinical trials in women had inconsistent outcomes, sparking uncertainty about adherence requirements and reluctance in evaluating on-demand regimens. We analyzed data from published FTC/TDF-PrEP trials to establish efficacy ranges in cisgender women. In a 'bottom-up' approach, we modeled hypotheses in the context of risk-group-specific, adherence-efficacy profiles and challenged those hypotheses with clinical data. We found that different clinical outcomes were related to the proportion of women taking the product, allowing coherent interpretation of the data. Our analysis showed that 90% protection was achieved when women took some product. We found that hypotheses of putative male/female differences were either not impactful or statistically inconsistent with clinical data. We propose that differing clinical outcomes could arise from pill-taking behavior rather than biological factors driving specific adherence requirements in cisgender women.

A randomized clinical trial of on-demand oral pre-exposure prophylaxis does not modulate lymphoid/myeloid HIV target cell density in the foreskin

OBJECTIVES

As topical pre-exposure prophylaxis (PrEP) has been shown to cause immune modulation in rectal or cervical tissue, our aim was to examine the impact of oral PrEP on lymphoid and myeloid changes in the foreskin in response to dosing and timing of drug administration.

DESIGN

HIV-negative male individuals ( n  = 144) were recruited in South Africa and Uganda into an open-label randomized controlled trial in a 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 ratio to control arm (with no PrEP) or one of eight arms receiving emtricitabine-tenofovir disoproxil fumarate (F/TDF) or emtricitabine-tenofovir alafenamide (F/TAF) at one of two different doses, 5 or 21 h before undergoing voluntary medical male circumcision (VMMC).

METHODS

After dorsal-slit circumcision, foreskin tissue sections were embedded into Optimal Cutting Temperature media and analysed, blinded to trial allocation, to determine numbers of CD4 + CCR5 + , CD1a + cells and claudin-1 expression. Cell densities were correlated with tissue-bound drug metabolites and p24 production after ex-vivo foreskin challenge with HIV-1 bal .

RESULTS

There was no significant difference in CD4 + CCR5 + or CD1a + cell numbers in foreskins between treatment arms compared with the control arm. Claudin-1 expression was 34% higher ( P  = 0.003) in foreskin tissue from participants receiving PrEP relative to controls, but was no longer statistically significant after controlling for multiple comparisons. There was neither correlation of CD4 + CCR5 + , CD1a + cell numbers, or claudin-1 expression with tissue-bound drug metabolites, nor with p24 production after ex-vivo viral challenge.

CONCLUSION

Oral doses and timing of on-demand PrEP and in-situ drug metabolite levels in tissue have no effect on numbers or anatomical location of lymphoid or myeloid HIV target cells in foreskin tissue.

Sexual behaviours and correlates of condom use among HIV-discordant couples from eastern China: a cross-sectional study

OBJECTIVES

To investigate sexual behaviours among HIV-discordant heterosexual couples and assess the correlates of condom use at the couple level.

DESIGN

Cross-sectional study.

SETTING

Seven prefectures along the Yangtze River in the Anhui Province, China.

PARTICIPANTS

We included 412 participants aged 18 years or older (206 married HIV-discordant couples).

PRIMARY AND SECONDARY OUTCOME MEASURES

In this study, sexual behaviours included marital or extramarital sex in the past 6 months, as well as the frequency of marital sex and condom use (always, sometimes or never) if having marital sex in the past 6 months. We used stepwise ordinal logistic regression modelling to determine the correlates of condom use.

RESULTS

In total, 63.1% (130 of 206) of couples had marital sex in the past 6 months, of which 89.2% (116 of 130) used condoms consistently. Couples with more marital duration (OR=1.15; 95% CI: 1.03, 1.28) were more inclined to adhere to condom use, whereas those lacking support and care (OR=0.25; 95% CI: 0.07, 0.94) and being remarried (OR=0.08; 95% CI: 0.02, 0.43) were associated with less condom use. In addition, HIV-positive respondents were more likely to have extramarital sex than HIV-negative respondents (p=0.015).

CONCLUSIONS

The extramarital sex of HIV-positive spouses should be considered. Implementation of interventions, such as increasing support and care between spouses to promote marital intimacy and stability, could reduce unprotected sexual behaviour.

Critical tests of fuzzy trace theory in brain and behavior: uncertainty across time, probability, and development

Uncertainty permeates decisions from the trivial to the profound. Integrating brain and behavioral evidence, we discuss how probabilistic (varied outcomes) and temporal (delayed outcomes) uncertainty differ across age and individuals; how critical tests adjudicate between theories of uncertainty (prospect theory and fuzzy-trace theory); and how these mechanisms might be represented in the brain. The same categorical gist representations of gains and losses account for choices and eye-tracking data in both value-allocation (add money to gambles) and risky-choice tasks, disconfirming prospect theory and confirming predictions of fuzzy-trace theory. The analysis is extended to delay discounting and disambiguated choices, explaining hidden-zero effects that similarly turn on categorical distinctions between some gain and no gain, certain gain and uncertain gain, gain and loss, and now and later. Bold activation implicates dorsolateral prefrontal and posterior parietal cortices in gist strategies that are not just one tool in a grab-bag of cognitive options but rather are general strategies that systematically predict behaviors across many different tasks involving probabilistic and temporal uncertainty. High valuation (e.g., ventral striatum; ventromedial prefrontal cortex) and low executive control (e.g., lateral prefrontal cortex) contribute to risky and impatient choices, especially in youth. However, valuation in ventral striatum supports reward-maximizing and gist strategies in adulthood. Indeed, processing becomes less "rational" in the sense of maximizing gains and more noncompensatory (eye movements indicate fewer tradeoffs) as development progresses from adolescence to adulthood, as predicted. Implications for theoretically predicted "public-health paradoxes" are discussed, including gist versus verbatim thinking in drug experimentation and addiction.

Multiple indicators of violence against female sex workers and its associated factors in Ghana: Evidence from the 2015 integrated bio-behavioral surveillance survey cross-sectional study

Background and Aims

Violence against female sex workers (FSWs) is a widespread phenomenon, especially in African nations like Ghana where sex work is outlawed primarily because of the pervasive worldview that sex work is a contravention of morality. Violence against FSWs deters them from accessing critical health services and heightens their risk of STIs including HIV infection. The study examined the prevalence and the associated factors of multiple indicators of violence against FSWs.

Methods

The study utilized a cross-sectional secondary data from the 2015 Integrated Bio-Behavioral Surveillance Survey conducted among FSWs and their nonpaying partners by Ghana AIDS Commission. We analysed data on a total of 4279 participants. Bivariate, and multivariable logistic regression analyses were utilized to identify factors associated with physical and sexual violence against FSWs. Data were analysed using Stata version 15.

Results

Of the 4279 FSWs, 433 (10%) and 1059 (25%) suffered physical and sexual violence, respectively. The predictors of physical violence are being a seater (adjusted odds ratio [aOR] = 0.53, 95% confidence interval [CI]: 0.36-0.74), aged ≥40 (aOR = 0.23, 95% CI: 0.08-0.64), nonuse of drugs (aOR = 0.56, 95% CI: 0.44-0.70), not using alcohol before sex (aOR = 0.69, 95% CI: 0.56-0.86) and petty business (aOR = 1.39, 95% CI: 1.05-1.82). Sexual violence was predicted by those aged 31-40 (aOR = 0.68, 95% CI: 0.49-0.94) and age ≥40 (aOR = 0.38, 95% CI: 0.22-0.66), currently married (aOR = 0.42, 95% CI: 0.27-0.67), having no living children (aOR = 0.69, 95% CI: 0.51-0.94), nonuse of drugs (aOR = 0.80, 95% CI: 0.68-0.94), and not using alcohol before sex (aOR = 0.74, 95% CI: 0.63-0.86). Region was associated with both physical and sexual violence. Both physical and sexual violence had negative consequences on consistency of condom use and condom failure among FSWs.

Conclusion

Physical and sexual violence against FSWs is pervasive, and a critical public health issue in Ghana. The identified associated factors could be considered as part of an overall strategy aimed at addressing the menace.

Synthesis of protective oral PrEP adherence levels in cisgender women using convergent clinical- and bottom-up modeling

Globally, most HIV infections occur in heterosexual women in resource-limited settings. In these settings, female self-protection with generic emtricitabine/tenofovir disoproxil fumarate pre-exposure prophylaxis (FTC/TDF-PrEP) may constitute a major pillar of the HIV prevention portfolio. However, clinical trials in women had inconsistent outcomes, sparking uncertainty regarding risk-group specific adherence requirements and causing reluctance in testing and recommending on-demand regimen in women. We analyzed all FTC/TDF-PrEP trials to establish PrEP efficacy ranges in women. In a 'bottom-up' approach, we modeled hypotheses corroborating risk-group specific adherence-efficacy profiles. Finally, we used the clinical efficacy ranges to (in-)validate hypotheses. We found that different clinical outcomes could solely be explained by the proportion of enrolled participants not taking the product, allowing, for the first time, to unify clinical observations. This analysis showed that 90% protection was achieved, when women took some of the product. Using 'bottom-up' modelling, we found that hypotheses of putative male/female differences were either irrelevant, or statistically inconsistent with clinical data. Furthermore, our multiscale modelling indicated that 90% protection was achieved if oral FTC/TDF was taken at least twice weekly.

The Humanized Mouse Model: What Added Value Does It Offer for HIV Research?

In the early 2000s, novel humanized mouse models based on the transplantation of human hematopoietic stem and progenitor cells (HSPCs) into immunocompromised mice were introduced (hu mice). The human HSPCs gave rise to a lymphoid system of human origin. The HIV research community has greatly benefitted from these hu mice. Since human immunodeficiency virus (HIV) type 1 infection results in a high-titer disseminated HIV infection, hu mice have been of great value for all types of HIV research from pathogenesis to novel therapies. Since the first description of this new generation of hu mice, great efforts have been expended to improve humanization by creating other immunodeficient mouse models or supplementing mice with human transgenes to improve human engraftment. Many labs have their own customized hu mouse models, making comparisons quite difficult. Here, we discuss the different hu mouse models in the context of specific research questions in order to define which characteristics should be considered when determining which hu mouse model is appropriate for the question posed. We strongly believe that researchers must first define their research question and then determine whether a hu mouse model exists, allowing the research question to be studied.

Public health interventions, priority populations, and the impact of COVID-19 disruptions on hepatitis C elimination among people who have injected drugs in Montreal (Canada): A modeling study

BACKGROUND

In Montreal (Canada), high hepatitis C virus (HCV) seroincidence (21 per 100 person-years in 2017) persists among people who have injected drugs (PWID) despite relatively high testing rates and coverage of needle and syringe programs (NSP) and opioid agonist therapy (OAT). We assessed the potential of interventions to achieve HCV elimination (80% incidence reduction and 65% reduction in HCV-related mortality between 2015 and 2030) in the context of COVID-19 disruptions among all PWID and PWID living with HIV.

METHODS

Using a dynamic model of HCV-HIV co-transmission, we simulated increases in NSP (from 82% to 95%) and OAT (from 33% to 40%) coverage, HCV testing (every 6 months), or treatment rate (100 per 100 person-years) starting in 2022 among all PWID and PWID living with HIV. We also modeled treatment scale-up among active PWID only (i.e., people who report injecting in the past six months). We reduced intervention levels in 2020-2021 due to COVID-19-related disruptions. Outcomes included HCV incidence, prevalence, and mortality, and proportions of averted chronic HCV infections and deaths.

RESULTS

COVID-19-related disruptions could have caused temporary rebounds in HCV transmission. Further increasing NSP/OAT or HCV testing had little impact on incidence. Scaling-up treatment among all PWID achieved incidence and mortality targets among all PWID and PWID living with HIV. Focusing treatment on active PWID could achieve elimination, yet fewer projected deaths were averted (36% versus 48%).

CONCLUSIONS

HCV treatment scale-up among all PWID will be required to eliminate HCV in high-incidence and prevalence settings. Achieving elimination by 2030 will entail concerted efforts to restore and enhance pre-pandemic levels of HCV prevention and care.

The population impact of herpes simplex virus type 2 (HSV-2) vaccination on the incidence of HSV-2, HIV and genital ulcer disease in South Africa: a mathematical modelling study

BACKGROUND

Evidence suggests HSV-2 infection increases HIV acquisition risk and HIV/HSV-2 coinfection increases transmission risk of both infections. We analysed the potential impact of HSV-2 vaccination in South Africa, a high HIV/HSV-2 prevalence setting.

METHODS

We adapted a dynamic HIV transmission model for South Africa to incorporate HSV-2, including synergistic effects with HIV, to evaluate the impact of: (i) cohort vaccination of 9-year-olds with a prophylactic vaccine that reduces HSV-2 susceptibility; (ii) vaccination of symptomatically HSV-2-infected individuals with a therapeutic vaccine that reduces HSV shedding.

FINDINGS

An 80% efficacious prophylactic vaccine offering lifetime protection with 80% uptake could reduce HSV-2 and HIV incidence by 84.1% (95% Credibility Interval: 81.2-86.0) and 65.4% (56.5-71.6) after 40 years, respectively. This reduces to 57.4% (53.6-60.7) and 42.1% (34.1-48.1) if efficacy is 50%, 56.1% (53.4-58.3) and 41.5% (34.2-46.9) if uptake is 40%, and 29.4% (26.0-31.9) and 24.4% (19.0-28.7) if protection lasts 10 years. An 80% efficacious therapeutic vaccine offering lifetime protection with 40% coverage among symptomatic individuals could reduce HSV-2 and HIV incidence by 29.6% (21.8-40.9) and 26.4% (18.5-23.2) after 40 years, respectively. This reduces to 18.8% (13.7-26.4) and 16.9% (11.7-25.3) if efficacy is 50%, 9.7% (7.0-14.0) and 8.6% (5.8-13.4) if coverage is 20%, and 5.4% (3.8-8.0) and 5.5% (3.7-8.6) if protection lasts 2 years.

INTERPRETATION

Prophylactic and therapeutic vaccines offer promising approaches for reducing HSV-2 burden and could have important impact on HIV in South Africa and other high prevalence settings.

FUNDING

WHO, NIAID.

Prevalence and determinants of heterosexual anal-intercourse among female sex workers in India: Findings from nationwide cross-sectional biological and behavioural survey

BACKGROUND

The vulnerability of female sex workers (FSWs) to HIV infection increases if unprotected heterosexual anal intercourse (HAI) is practiced.

OBJECTIVES

To estimate the prevalence of HAI among FSWs, and associated factors, and prevalence of consistent condom use (CCU) during HAI and associated factors.

METHODS

Analysis of cross-sectional data from nationwide biological and behavioural survey, conducted at 73 randomly selected domains with sample size of 27,000 in India.

RESULTS

A total of 25,932 FSWs were included in the analysis, after excluding 1075 (3.9%) FSWs for which the data were incomplete. The prevalence of HAI was 29.9% (95% CI, 29.3, 30.4); The CCU during HAI in the last one month was 58.9%. Younger age at the start of sex work, use of mobile phone/internet for soliciting client, home as a place of sex work, consumption of alcohol/drug, and physical violence against FSWs were associated with higher odds of HAI. Frequent contact with outreach workers, awareness of sexually transmitted infection, and older age at the start of sex work was associated with CCU.

CONCLUSION

Prevalence of HAI was high among FSW in India. The national program could target those factors that reduce the odds of HAI and/or promote CCU.

Brief Report: Dapivirine Ring HIV-1 Prevention Effectiveness for Women Engaged in Vaginal and Anal Intercourse: Insights From Mathematical Modeling

BACKGROUND

The dapivirine vaginal ring reduces the risk of HIV-1 acquisition in acts of vaginal intercourse (VI), and although it does not offer HIV-1 protection in acts of anal intercourse (AI), it may provide some overall risk reduction for women for whom most sex acts are vaginal. We estimated the protective effect of the ring among women with high ring adherence engaged in both VI and AI.

METHODS

We developed a microsimulation model using data from the MTN-020/ASPIRE trial. Among women who reported any AI, we estimated the proportion of all sex acts that were AI. Model scenarios varied this proportion among women engaged in both VI and AI from 5% to 30%, including the trial-observed median proportion of 6.3% of all acts being AI. In primary analyses, dapivirine ring efficacy was model-calibrated at 70% for vaginal exposures and assumed to be 0% for anal exposures.

RESULTS

Among highly adherent women for whom 6.3% of sex acts were AI, the ring reduced HIV-1 risk by 53% (interquartile range: 44, 60), with a decline to 26% (interquartile range: 16, 36) among women for whom 30% of acts were AI. Ring effectiveness was less than 40% among women for whom AI accounted for greater than 16% of all sex acts, although this represented less than 5% of all women in the ASPIRE trial.

CONCLUSIONS

For most women, including those who engage in AI, because most HIV-1 risk occurs in acts of vaginal sex, the dapivirine vaginal ring can provide important HIV-1 protection.

The initial interplay between HIV and mucosal innate immunity

Human Immunodeficiency Virus (HIV) is still one of the major global health issues, and despite significant efforts that have been put into studying the pathogenesis of HIV infection, several aspects need to be clarified, including how innate immunity acts in different anatomical compartments. Given the nature of HIV as a sexually transmitted disease, one of the aspects that demands particular attention is the mucosal innate immune response. Given this scenario, we focused our attention on the interplay between HIV and mucosal innate response: the different mucosae act as a physical barrier, whose integrity can be compromised by the infection, and the virus-cell interaction induces the innate immune response. In addition, we explored the role of the mucosal microbiota in facilitating or preventing HIV infection and highlighted how its changes could influence the development of several opportunistic infections. Although recent progress, a proper characterization of mucosal innate immune response and microbiota is still missing, and further studies are needed to understand how they can be helpful for the formulation of an effective vaccine.

Epidemiology of herpes simplex virus type 2 in Europe: systematic review, meta-analyses, and meta-regressions

Background

Herpes simplex virus type 2 (HSV-2) infection is a globally prevalent, life-long, sexually transmitted infection. This study characterized HSV-2 seroprevalence in Europe for various at-risk populations and proportions of HSV-2 detection in genital ulcer disease (GUD) and in genital herpes. Data on neonatal herpes and HSV-2's contribution to HIV transmission were also reviewed.

Methods

Cochrane and PRISMA guidelines were followed to systematically review, synthesize, and report HSV-2 related findings. The search was conducted in PubMed and Embase databases up to February 20, 2022. Any publication reporting data on the outcome measures was included. Meta-analyses and meta-regressions were conducted.

Findings

211 relevant reports were identified, including 12 overall incidence measures, 294 overall (813 stratified by factors such as age and sex) seroprevalence measures, 13 overall (15 stratified by sex) proportions of HSV-2 detection in clinically diagnosed GUD, and 70 overall (183 stratified by factors such as age and sex) proportions of HSV-2 detection in laboratory-confirmed genital herpes. Pooled mean seroprevalence was 12.4% (95% CI: 11.5-13.3%) among general populations, 27.8% (95% CI: 17.5-39.4%) among men who have sex with men, 46.0% (95% CI: 40.1-51.8%) among people living with HIV and people in HIV discordant couples, and 63.2% (95% CI: 55.5-70.6%) among female sex workers. Most measures showed heterogeneity in HSV-2 seroprevalence. The pooled mean seroprevalence among general populations increased with age and was 0.65-fold (95% CI: 0.58-0.74) lower in men than women. Seroprevalence decreased by 1% per calendar year. Pooled mean proportions of HSV-2 detection in GUD and in genital herpes were 22.0% (95% CI: 15.3-29.6%) and 66.0% (95% CI: 62.9-69.1%), respectively. HSV-2 detection in genital herpes cases was 1.21-fold (95% CI: 1.10-1.32) higher in men compared to women and decreased by 1% per calendar year. Incidence of neonatal herpes indicated an increasing trend.

Interpretation

Although seroprevalence is declining, a significant proportion of Europe's population is infected with HSV-2. HSV-2 accounts for approximately one-fifth of GUD cases and two-thirds of genital herpes cases. Findings support the need to invest in HSV-2 vaccine development, and sexual and reproductive health services.

Funding

Qatar National Research Fund [NPRP 9-040-3-008] and pilot funding from the Biomedical Research Program at Weill Cornell Medicine in Qatar supported this study.

Women for science and science for women: Gaps, challenges and opportunities towards optimizing pre-exposure prophylaxis for HIV-1 prevention

Preventing new HIV infections remains a global challenge. Young women continue to bear a disproportionate burden of infection. Oral pre-exposure prophylaxis (PrEP), offers a novel women-initiated prevention technology and PrEP trials completed to date underscore the importance of their inclusion early in trials evaluating new HIV PrEP technologies. Data from completed topical and systemic PrEP trials highlight the role of gender specific physiological and social factors that impact PrEP uptake, adherence and efficacy. Here we review the past and current developments of HIV-1 prevention options for women with special focus on PrEP considering the diverse factors that can impact PrEP efficacy. Furthermore, we highlight the importance of inclusion of female scientists, clinicians, and community advocates in scientific efforts to further improve HIV prevention strategies.

'Sometimes it is not about men': Gendered and generational discourses of caregiving HIV transmission in a rural South African setting

ABSTRACTIn this paper, we examine a prominent interpretation of HIV risk in a rural South African setting experiencing a severe HIV epidemic well into older ages: the discourse of caregiving HIV transmission. By caregiving transmission, we refer to HIV infection resulting from caring for family members who are living with HIV and may be sick with AIDS-related illnesses. We draw on individual life history and community focus group interviews with men and women aged 40-80+, as well as interviews with health workers providing HIV counselling and testing services at local health facilities in their communities. We illustrate the social and strategic role caregiving HIV transmission discourses play in re-signifying HIV as a sexless infection for older women, thereby promoting HIV testing as well as blameless acceptance of an HIV diagnosis. We further highlight the role of rural health workers who serve as medical epistemic bricoleurs, vernacularising global HIV counselling and prevention messages by blending ideas of gender, generation, and local lived experiences and practices so that they resonate with community norms, values and understandings. Our study highlights the gendered and generational complexities and challenges experienced by rural South Africans aging in a community over-burdened by an HIV epidemic and AIDS-related mortality.

Effect of Screening and Treatment for Gonorrhea and Chlamydia on HIV Incidence Among Men Who Have Sex With Men in the United States: A Modeling Analysis

BACKGROUND

Previous models have estimated the total population attributable fraction of Neisseria gonorrhoeae and Chlamydia trachomatis (NG/CT) on HIV incidence among men who have sex with men (MSM), but this does not represent realistic intervention effects. We estimated the potential impact of screening for NG/CT on downstream incidence of HIV among MSM.

METHODS

Using a network model, we estimated the effects of varying coverage levels for sexually transmitted infection screening among different priority populations: all sexually active MSM regardless of HIV serostatus, MSM with multiple recent (past 6 months) sex partners regardless of serostatus, MSM without HIV, and MSM with HIV. Under the assumption that all screening events included a urethral test, we also examined the effect of increasing the proportion of screening events that include rectal screening for NG/CT on HIV incidence.

RESULTS

Increasing annual NG/CT screening among sexually active MSM by 60% averted 4.9% of HIV infections over a 10-year period (interquartile range, 2.8%-6.8%). More HIV infections were averted when screening was focused on MSM with multiple recent sex partners: 60% coverage among MSM with multiple recent sex partners averted 9.8% of HIV infections (interquartile range, 8.1%-11.6%). Increased sexually transmitted infection screening among MSM without HIV averted more new HIV infections compared with the transmissions averted because of screening MSM with HIV, but fewer NG/CT tests were needed among MSM with HIV to avert a single new HIV infection.

CONCLUSIONS

Screening of NG/CT among MSM is expected to lead to modest but clinically relevant reductions in HIV incidence among MSM.

Feasibility of hepatitis B elimination in high-income countries with ongoing immigration

BACKGROUND & AIMS

Addressing HBV is vital to meeting the World Health Organization (WHO)'s viral hepatitis elimination goals, as 47% of viral hepatitis complications can be attributed to HBV. The objective of this study is to develop an agent-based model determining which integrated strategies involving vaccination, screening, and treatment would achieve the WHO's goals.

METHODS

We developed an agent-based model to characterize the HBV epidemic in a high-income country with ongoing immigration. The spread of HBV was simulated through sexual networks and perinatal transmission. Model parameters were estimated from the literature and calibrated against historical HBV data. Sensitivity analyses were performed to assess the uncertainty.

RESULTS

We predict that under the current strategies, the incidence of acute hepatitis B, and HBV-attributable decompensated cirrhosis and hepatocellular carcinoma would decrease by 64.5%, 9.4%, and 10.5% between 2015-2030, respectively. However, the incidence of chronic hepatitis B and liver-related deaths would increase by 26.6% and 1.0% between 2015-2030, respectively. Results were sensitive to the number of immigrants and HBV prevalence in immigrants.

CONCLUSIONS

The results suggest that the current vaccination, screening, and treatment strategies will be inadequate to achieve WHO elimination goals. Even with extensive integrated scale-up in vaccination, screening, and treatment, the morbidity and mortality targets may not be reachable, highlighting the need for a re-evaluation of the global strategy for HBV, the importance of developing curative therapy for HBV, and of establishing tailored strategies to prevent long-term sequelae and improve health in immigrants.

LAY SUMMARY

We have developed a model that reflects the dynamics of hepatitis B virus (HBV) transmission in a high-income country with ongoing immigration, which enabled us to forecast the epidemiology of HBV for policy-level decision making. Our analysis suggests that current vaccination, screening, and treatment strategies are inadequate to achieve the WHO goals of eliminating chronic hepatitis B. Even with extensive integrated scale-up in vaccination, screening, and treatment, the morbidity and mortality targets may not be reachable.

Acknowledging and addressing the gender disparity in pre-exposure prophylaxis use for HIV prevention

Objective

One in four persons living with HIV in the USA is a woman. While the annual HIV diagnoses for 2019 decreased by approximately 9% when compared with 2015, this decrease was seen in men, while the rates remained stable for women. Pre-exposure prophylaxis (PrEP) is one major biomedical tool that could benefit women at risk of HIV. However, women only account for approximately 5% of PrEP users annually. The objective of this study is to identify and address the gender disparity in PrEP use.

Methods

This study used epidemiological data from the AIDSVu database to confirm the presence of a gender disparity in PrEP use across the USA. Cross-sectional data from 2019 showed that PrEP use was significantly higher in men, which suggested the existence of a disparity. The PrEP-to-Need ratio was then used to examine the trends in PrEP use relative to the rate of HIV infections, from 2012 to 2019, and to confirm the existence of the gender disparity in PrEP use.

Key findings

There is a marked gender disparity in PrEP use. This disparity is widening and therefore demands more attention to women at risk of HIV. Some recommendations for addressing the disparity include the following: raising awareness, capacity building for providers, scaling up efforts to better reach women at risk of HIV and additional research to understand the drivers of the disparity.

Conclusions

Policy makers could therefore prioritize the health outcomes of women by promoting research and education aimed at extending PrEP offerings to effectively reach women.

Risk heterogeneity in compartmental HIV transmission models of ART as prevention in Sub-Saharan Africa: A scoping review

BACKGROUND

Transmission models provide complementary evidence to clinical trials about the potential population-level incidence reduction attributable to ART (ART prevention impact). Different modelling assumptions about risk heterogeneity may influence projected ART prevention impacts. We sought to review representations of risk heterogeneity in compartmental HIV transmission models applied to project ART prevention impacts in Sub-Saharan Africa.

METHODS

We systematically reviewed studies published before January 2020 that used non-linear compartmental models of sexual HIV transmission to simulate ART prevention impacts in Sub-Saharan Africa. We summarized data on model structure/assumptions (factors) related to risk and intervention heterogeneity, and explored multivariate ecological associations of ART prevention impacts with modelled factors.

RESULTS

Of 1384 search hits, 94 studies were included. 64 studies considered sexual activity stratification and 39 modelled at least one key population. 21 studies modelled faster/slower ART cascade transitions (HIV diagnosis, ART initiation, or cessation) by risk group, including 8 with faster and 4 with slower cascade transitions among key populations versus the wider population. In ecological analysis of 125 scenarios from 40 studies (subset without combination intervention), scenarios with risk heterogeneity that included turnover of higher risk groups were associated with smaller ART prevention benefits. Modelled differences in ART cascade across risk groups also influenced the projected ART benefits, including: ART prioritized to key populations was associated with larger ART prevention benefits. Of note, zero of these 125 scenarios considered lower ART coverage among key populations.

CONCLUSION

Among compartmental transmission models applied to project ART prevention impacts in Sub-Saharan Africa, representations of risk heterogeneity and projected impacts varied considerably. Inclusion/exclusion of risk heterogeneity with turnover, and intervention heterogeneity across risk groups could influence the projected impacts of ART scale-up. These findings highlight a need to capture risk heterogeneity with turnover and cascade heterogeneity when projecting ART prevention impacts.

Risk of Human Immunodeficiency Virus Acquisition Among High-Risk Heterosexuals With Nonviral Sexually Transmitted Infections: A Systematic Review and Meta-Analysis

BACKGROUND

Nonviral sexually transmitted infections (STIs) increase risk of sexually acquired human immunodeficiency virus (HIV) infection. Updated risk estimates carefully scrutinizing temporality bias of studies are needed.

METHODS

We conducted a systematic review (PROSPERO CRD42018084299) of peer-reviewed studies evaluating variation in risk of HIV infection among high-risk heterosexuals diagnosed with any of: Chlamydia trachomatis, Mycoplasma genitalium, Neisseria gonorrhoeae, Treponema pallidum, and/or Trichomonas vaginalis. We searched PubMed, Web of Science, and Embase databases through December 2017 and included studies where STIs and HIV were assessed using laboratory tests or medical examinations and where STI was diagnosed before HIV. After dual screening, data extraction, and risk of bias assessment, we meta-analytically pooled risk ratios (RRs).

RESULTS

We found 32 eligible studies reporting k = 97 effect size estimates of HIV acquisition risk due to infection with one of the abovementioned STIs. Most data were based on women engaged in sex work or other high-risk occupations in developing countries. Many studies did not measure or adjust for known confounders, including drug injection and condom use, and most were at medium or high risk of bias because of the potential for undetected HIV infection to have occurred before STI infection. Human immunodeficiency virus acquisition risk increased among women infected with any pathogen; the effect was greatest for women infected with Mycoplasma genitalium (RR, 3.10; 95% confidence interval [CI], 1.63-5.92; k = 2) and gonorrhea (RR, 2.81; 95% CI, 2.25-3.50; k = 16) but also statistically significant for women infected with syphilis (RR, 1.67; 95% CI, 1.23-2.27; k = 17), trichomonas (RR, 1.54; 95% CI, 1.31-1.82; k = 17), and chlamydia (RR, 1.49; 95% CI, 1.08-2.04; k = 14). For men, data were space except for syphilis (RR, 1.77; 95% CI, 1.22-2.58; k = 5).

CONCLUSION

Nonviral STI increases risk of heterosexual HIV acquisition, although uncertainty remains because of risk of bias in primary studies.

The Effect of HIV Programs in South Africa on National HIV Incidence Trends, 2000-2019

BACKGROUND

Recent studies have shown HIV incidence declines at a population level in several African countries. However, these studies have not directly quantified the extent to which incidence declines are attributable to different HIV programs.

METHODS

We calibrated a mathematical model of the South African HIV epidemic to age- and sex-specific data from antenatal surveys, household surveys, and death registration, using a Bayesian approach. The model was also parameterized using data on self-reported condom use, voluntary medical male circumcision (VMMC), HIV testing, and antiretroviral treatment (ART). Model estimates of HIV incidence were compared against the incidence rates that would have been expected had each program not been implemented.

RESULTS

The model estimated incidence in 15-49 year olds of 0.84% (95% CI: 0.75% to 0.96%) at the start of 2019. This represents a 62% reduction (95% CI: 55% to 66%) relative to 2000, a 47% reduction (95% CI: 42% to 51%) relative to 2010, and a 73% reduction (95% CI: 68% to 77%) relative to the incidence that would have been expected in 2019 in the absence of any interventions. The reduction in incidence in 2019 because of interventions was greatest for ART and condom promotion, with VMMC and behavior change after HIV testing having relatively modest impacts. HIV program impacts differed significantly by age and sex, with condoms and VMMC having greatest impact in youth, and overall incidence reductions being greater in men than in women.

CONCLUSIONS

HIV incidence in South Africa has declined substantially since 2000, with ART and condom promotion contributing most significantly to this decline.

Immune parameters of HIV susceptibility in the female genital tract before and after penile-vaginal sex

Background

In women, most HIV infections are acquired through penile-vaginal sex. Inflammation in the female genital tract (FGT) increases the risk of HIV acquisition and transmission, likely through recruitment of HIV target cells and disruption of epithelial barrier integrity. Although sex may have important immune and epithelial effects, the impact of receptive penile-vaginal sex on the immune correlates of HIV susceptibility in the female genital tract is not well described.

Methods

STI-free heterosexual couples were recruited to the Sex, Couples and Science (SECS) Study, with the serial collection of cervical secretions (CVS), endocervical cytobrushes, blood and semen before and up to 72 h after either condomless (n = 29) or condom-protected (n = 8) penile-vaginal sex. Immune cells were characterized by flow cytometry, and immune factors including cytokines and soluble E-cadherin (sE-cad; a marker of epithelial disruption) were quantified by multiplex immunoassay. Co-primary endpoints were defined as levels of IP-10 and IL-1α, cytokines previously associated with increased HIV susceptibility.

Results

Here we show that cervicovaginal levels of vaginal IP-10, sE-cad and several other cytokines increase rapidly after sex, regardless of condom use. The proportion of endocervical HIV target cells, including Th17 cells, activated T cells, and activated or mature dendritic cells (DCs) also increase, particularly after condomless sex. Although most of these immune changes resolve within 72 h, increases in activated cervical CD4 + T cells and Tcm persist beyond this time.

Conclusions

Penile-vaginal sex induces multiple genital immune changes that may enhance HIV susceptibility during the 72 h post-sex window that is critical for virus acquisition. This has important implications for the mucosal immunopathogenesis of HIV transmission.

Women who acquire HIV most commonly do so during penile-vaginal sex. Although the risk of HIV acquisition is higher when there is pre-existing inflammation in the female genital tract, the impact of receptive penile-vaginal sex itself on immune markers of HIV susceptibility in the genital tract has not been widely studied. We recruited heterosexual couples, without HIV or sexually-transmitted infections, and studied the impact of a single episode of penile-vaginal sex on immune cells and proteins in the female genital tract. We found that some markers within the cervix and vagina increased immediately after sex, then returned to normal. We noticed differences in these changes depending on whether the sex was condom-protected and whether the male partner was circumcised. Our findings might help us to understand how sex impacts the immune system and how this might contribute to HIV acquisition.

Mohammadi et al. evaluate immune markers and cell types associated with HIV susceptibility in the female genital tract before and after penile-vaginal sex. The authors report that these immune parameters increase rapidly and transiently after sex, with condom use affecting some of the changes observed.

Contribution of Sex Differences to HIV Immunology, Pathogenesis, and Cure Approaches

Approximately 38 million people were living with human immunodeficiency virus (HIV) in 2020 and 53% of those infected were female. A variety of virological and immunological sex-associated differences (sexual dimorphism) in HIV infection have been recognized in males versus females. Social, behavioral, and societal influences play an important role in how the HIV pandemic has affected men and women differently. However, biological factors including anatomical, physiologic, hormonal, and genetic differences in sex chromosomes can each contribute to the distinct characteristics of HIV infection observed in males versus females. One striking example of this is the tendency for women to have lower HIV plasma viral loads than their male counterparts early in infection, though both progress to AIDS at similar rates. Sex differences in acquisition of HIV, innate and adaptive anti-HIV immune responses, efficacy/suitability of specific antiretroviral drugs, and viral pathogenesis have all been identified. Sex differences also have the potential to affect viral persistence, latency, and cure approaches. In this brief review, we summarize the major biological male/female sex differences in HIV infection and their importance to viral acquisition, pathogenesis, treatment, and cure efforts.

The Impact of Genital Ulcers on HIV Transmission Has Been Underestimated—A Critical Review

In the early 1990s, several observational studies determined that genital ulcer disease (GUD), in either the index or the exposed person, facilitates HIV transmission. Several meta-analyses have since presented associated risk ratios (RR) over the baseline per-act transmission probability (PATP) usually in the range of 2–5. Here we review all relevant observational studies and meta-analyses, and show that the estimation of RRs was, in most cases, biased by assuming the presence of GUD at any time during long follow-up periods, while active genital ulcers were present in a small proportion of the time. Only two studies measured the GUD co-factor effect in PATPs focusing on acts in which ulcers were present, and both found much higher RRs (in the range 11–112). We demonstrate that these high RRs can be reconciled with the studies on which currently accepted low RRs were based, if the calculations are restricted to the actual GUD episodes. Our results indicate that the effect of genital ulcers on the PATP of HIV might be much greater than currently accepted. We conclude that the medical community should work on the assumption that HIV risk is very high during active genital ulcers.

Detecting Selection in the HIV-1 Genome during Sexual Transmission Events

Little is known about whether and how variation in the HIV-1 genome affects its transmissibility. Assessing which genomic features of HIV-1 are under positive or negative selection during transmission is challenging, because very few virus particles are typically transmitted, and random genetic drift can dilute genetic signals in the recipient virus population. We analyzed 30 transmitter–recipient pairs from the Zurich Primary HIV Infection Study and the Swiss HIV Cohort Study using near full-length HIV-1 genomes. We developed a new statistical test to detect selection during transmission, called Selection Test in Transmission (SeTesT), based on comparing the transmitter and recipient virus population and accounting for the transmission bottleneck. We performed extensive simulations and found that sensitivity of detecting selection during transmission is limited by the strong population bottleneck of few transmitted virions. When pooling individual test results across patients, we found two candidate HIV-1 genomic features for affecting transmission, namely amino acid positions 3 and 18 of Vpu, which were significant before but not after correction for multiple testing. In summary, SeTesT provides a general framework for detecting selection based on genomic sequencing data of transmitted viruses. Our study shows that a higher number of transmitter–recipient pairs is required to improve sensitivity of detecting selection.

The impact of condom use on the HIV epidemic

Background: Condom promotion and supply was one the earliest interventions to be mobilized to address the HIV pandemic. Condoms are inexpensive and provide protection against transmission of HIV and other sexually transmitted diseases (STIs) as well as against unintended pregnancy. As many as 16 billion condoms may be used annually in all low- and middle-income countries (LMIC). In recent years the focus of HIV programs as been on testing and treatment and new technologies such as PrEP. Rates of condom use have stopped increasing short of UNAIDS targets and funding from donors is declining. Methods: We applied a mathematical HIV transmission model to 77 high HIV burden countries to estimate the number of HIV infections that would have occurred from 1990 to 2019 if condom use had remained at 1990 levels. Results: The results suggest that current levels of HIV would be five times higher without condom use and that the scale-up in condoms use averted about 117 million HIV infections. Conclusions: HIV programs should ensure that affordable condoms are consistently available and that the benefits of condom use are widely understood.

HPV and the Risk of HIV Acquisition in Women

The risk of HIV acquisition is low on a per-contact basis but increased by transmission co-factors such as other sexually transmitted infections (STIs). Human papillomavirus (HPV) is a prevalent STI that most individuals will acquire HPV in their lifetime. Current HPV vaccines can prevent newly acquired infections, but are largely ineffective against established HPV, complicating worldwide eradication efforts. In addition to being the causative agent of cervical cancer, accumulating evidence suggests that HPV infection and/or accompanying cervical inflammation increase the risk of HIV infection in men and women. The fact that immunological features observed during HPV infection overlap with cellular and molecular pathways known to enhance HIV susceptibility underscore the potential interplay between these two viral infections that fuel their mutual spread. Here we review current insights into how HPV infection and the generation of anti-HPV immunity contribute to higher HIV transmission rates, and the impact of HPV on mucosal inflammation, immune cell trafficking, and epithelial barrier function.

Inter-partner Agreement of Condom Use and Sexual Positioning in Male Couples

Accurate, reliable self-reports of sexual behavior are a crucial component of valid HIV risk-estimation and behavioral intervention evaluation, yet this data's reliability remains understudied. The goal of this study was to describe interpartner agreement on recent receptive anal intercourse (AI) and condomless receptive AI frequencies, among a sample of male couples. We quantified interpartner agreement on self-reported receptive AI and condomless receptive AI (absolute and relative to AI frequency), and position and condom use during a couple's most recent AI, using cross-sectional data from male partners (US, 2016-2017; N = 718 individuals). Proportional and statistical agreement (intraclass correlation coefficients (ICC), kappa (k)) were assessed. Observed agreement for receptive AI frequency was 49.44% (ICC (95% CI): 0.82(0.79, 0.84)) and for relative receptive frequency, 59.05% (ICC: 0.96 (0.85, 0.96). Agreement on condomless receptive AI was 90.21% (ICC: 0.78 (0.75, 0.82), and for relative condomless receptive AI, 91.15% (ICC: 0.80 (0.77, 0.83). Most recent AI position agreement was 89.42% (k (95% CI): 0.84 (0.80, 0.88)), and condom use, 98.89% (k: 0.82 (0.87, 0.98)). Observed agreement was higher among those who reported consistent positioning and condom use. Further research on self-reported sexual behavior data is needed to improve research validity and intervention effectiveness.

Impact of Canadian human immunodeficiency virus non-disclosure case law on experiences of violence from sexual partners among women living with human immunodeficiency virus in Canada: Implications for sexual rights

OBJECTIVES

People living with human immunodeficiency virus in Canada can face criminal charges for human immunodeficiency virus non-disclosure before sex, unless a condom is used and their viral load is <1500 copies/mL. We measured the reported impact of human immunodeficiency virus non-disclosure case law on violence from sexual partners among women living with human immunodeficiency virus in Canada.

METHODS

We used cross-sectional survey data from wave 3 participant visits (2017-2018) within Canadian HIV Women's Sexual and Reproductive Health Cohort Study; a longitudinal, community-based cohort of women living with human immunodeficiency virus in British Columbia, Ontario and Quebec. Our primary outcome was derived from response to the statement: '[HIV non-disclosure case law has] increased my experiences of verbal/physical/sexual violence from sexual partners'. Participants responding 'strongly agree/agree' were deemed to have experienced increased violence due to the law. Participants responding 'not applicable' (i.e. those without sexual partners) were excluded. Multivariate logistic regression identified factors independently associated with increased violence from sexual partners due to human immunodeficiency virus non-disclosure case law.

RESULTS

We included 619/937 wave 3 participants. Median age was 46 (interquartile range: 39-53) and 86% had experienced verbal/physical/sexual violence in adulthood. Due to concerns about human immunodeficiency virus non-disclosure case law, 37% had chosen not to have sex with a new partner, and 20% had disclosed their human immunodeficiency virus status to sexual partners before a witness. A total of 21% self-reported that human immunodeficiency virus non-disclosure case law had increased their experiences of verbal/physical/sexual violence from sexual partners. In adjusted analyses, women reporting non-White ethnicity (Indigenous; African/Caribbean/Black; Other), unstable housing and high human immunodeficiency virus-related stigma had significantly higher odds of reporting increased violence from sexual partners due to human immunodeficiency virus non-disclosure case law.

CONCLUSION

Findings bolster concerns that human immunodeficiency virus criminalization is a structural driver of intimate partner violence, compromising sexual rights of women living with human immunodeficiency virus. Human immunodeficiency virus non-disclosure case law intersects with other oppressions to regulate women's sexual lives.

Characteristics of low-tier female sex workers who engage in commercial sex with old male clients in Zhejiang province, China: a cross-sectional study

OBJECTIVES

To characterise low-tier female sex workers (FSWs) who engage in commercial sex with old male clients (OMCs).

DESIGN

Cross-sectional study.

SETTING

Twenty-one counties in Zhejiang province, China.

PARTICIPANTS

A total of 2647 low-tier FSWs who participated in our survey from September to November 2013, and responded to the question regarding whether they engaged in commercial sex with OMCs during the previous month.

MAIN OUTCOME MEASURES

Data on sociodemographic characteristics, sexual behaviours, risk perception of HIV/sexually transmitted infection (STI), ever exposure to an HIV prevention service and degree of self-efficacy regarding condom use were collected via a face-to-face questionnaire administered by trained interviewers.

RESULTS

Of the 2647 participants, 1165 (44.0%) had engaged in commercial sex with OMCs in the previous month. Low-tier FSWs working out of roadside shops, those who had engaged in sex work for longer, those with a larger number of clients, those who had engaged in anal or oral sex during the previous month, those currently using contraception measures, those who had STI symptoms and those who had been exposed to HIV prevention services during the previous 6 months were more likely to engage in commercial sex with OMCs. FSWs with a high level of education; those working out of small venues other than streets, hair salons and roadside shops; those who charged more for commercial sex; those who had sex with young clients during the previous month and those who had seen a doctor during the previous 6 months were less likely to engage in commercial sex with OMCs.

CONCLUSIONS

Low-tier FSWs who engaged in commercial sex with OMCs reported more risky behaviours than those who did not engage in this behaviour. Attention should be paid to these behaviours in future interventions targeting low-tier FSWs.

Overlapping Key Populations and HIV Transmission in Tijuana, Mexico: A Modelling Analysis of Epidemic Drivers

Tijuana, Mexico, has a concentrated HIV epidemic among overlapping key populations (KPs) including people who inject drugs (PWID), female sex workers (FSW), their male clients, and men who have sex with men (MSM). We developed a dynamic HIV transmission model among these KPs to determine the extent to which their unmet prevention and treatment needs is driving HIV transmission. Over 2020-2029 we estimated the proportion of new infections acquired in each KP, and the proportion due to their unprotected risk behaviours. We estimate that 43.7% and 55.3% of new infections are among MSM and PWID, respectively, with FSW and their clients making-up < 10% of new infections. Projections suggest 93.8% of new infections over 2020-2029 will be due to unprotected sex between MSM or unsafe injecting drug use. Prioritizing interventions addressing sexual and injecting risks among MSM and PWID are critical to controlling HIV in Tijuana.

Modelling the impact of HIV and HCV prevention and treatment interventions for people who inject drugs in Dar es Salaam, Tanzania

Introduction

People who inject drugs (PWID) in Dar es Salaam, Tanzania, have a high prevalence of HIV and hepatitis C virus (HCV). While needle and syringe programmes (NSP), opioid agonist therapy (OAT) and anti‐retroviral therapy (ART) are available in Tanzania, their coverage is sub‐optimal. We assess the impact of existing and scaled up harm reduction (HR) interventions on HIV and HCV transmission among PWID in Dar es Salaam.

Methods

An HIV and HCV transmission model among PWID in Tanzania was calibrated to data over 2006–2018 on HIV (∼30% and ∼67% prevalence in males and females in 2011) and HCV prevalence (∼16% in 2017), numbers on HR interventions (5254 ever on OAT in 2018, 766–1479 accessing NSP in 2017) and ART coverage (63.1% in 2015). We evaluated the impact of existing interventions in 2019 and impact by 2030 of scaling‐up the coverage of OAT (to 50% of PWID), NSP (75%, both combined termed “full HR”) and ART (81% with 90% virally suppressed) from 2019, reducing sexual HIV transmission by 50%, and/or HCV‐treating 10% of PWID infected with HCV annually.

Results

The model projects HIV and HCV prevalence of 19.0% (95% credibility interval: 16.4–21.2%) and 41.0% (24.4–49.0%) in 2019, respectively. For HIV, 24.6% (13.6–32.6%) and 70.3% (59.3–77.1%) of incident infections among male and female PWID are sexually transmitted, respectively. Due to their low coverage (22.8% for OAT, 16.3% for NSP in 2019), OAT and NSP averted 20.4% (12.9–24.7%) of HIV infections and 21.7% (17.0–25.2%) of HCV infections in 2019. Existing ART (68.5% coverage by 2019) averted 48.1% (29.7–64.3%) of HIV infections in 2019. Scaling up to full HR will reduce HIV and HCV incidence by 62.6% (52.5–74.0%) and 81.4% (56.7–81.4%), respectively, over 2019–2030; scaled up ART alongside full HR will decrease HIV incidence by 66.8% (55.6–77.5%), increasing to 81.5% (73.7–87.5%) when sexual risk is also reduced. HCV‐treatment alongside full HR will decrease HCV incidence by 92.4% (80.7–95.8%) by 2030.

Conclusions

Combination interventions, including sexual risk reduction and HCV treatment, are needed to eliminate HCV and HIV among PWID in Tanzania.

An economic evaluation of an intervention to increase demand for medical male circumcision among men aged 25-49 years in South Africa

BACKGROUND

Studies estimate that circumcising men between the ages of 20-30 years who have exhibited previous risky sexual behaviour could reduce overall HIV prevalence. Demand creation strategies for medical male circumcision (MMC) targeting men in this age group may significantly impact these prevalence rates.

OBJECTIVES

The objective of this study is to evaluate the cost-effectiveness and cost-benefit of an implementation science, pre-post study designed to increase the uptake of male circumcision for ages 25-49 at a fixed MMC clinic located in Gauteng Province, South Africa.

METHODS

A health care provider perspective was utilised to collect all costs. Costs were compared between the standard care scenario of routine outreach strategies and a full intervention strategy. Cost-effectiveness was measured as cost per mature man enrolled and cost per mature man circumcised. A cost-benefit analysis was employed by using the Bernoulli model to estimate the cases of HIV averted due to medical male circumcision (MMC), and subsequently translated to averted medical costs.

RESULTS

In the 2015 intervention, the cost of the intervention was $9445 for 722 men. The total HIV treatment costs averted due to the intervention were $542,491 from a public care model and $378,073 from a private care model. The benefit-cost ratio was 57.44 for the public care model and 40.03 for the private care model. The net savings of the intervention were $533,046 or $368,628 - depending on treatment in a public or private setting.

CONCLUSIONS

The intervention was cost-effective compared to similar MMC demand interventions and led to statistically significant cost savings per individual enrolled.

Could the 2010 HIV outbreak in Athens, Greece have been prevented? A mathematical modeling study

INTRODUCTION

In 2009 and 2010, Athens, Greece experienced a hepatitis C virus (HCV) and a Human Immunodeficiency Virus (HIV) outbreak among People Who Inject Drugs (PWID), respectively. The HCV outbreak was not detected, while that of HIV was identified in 2011. The integrated HIV-interventions, launched in early 2012, managed to reduce directly the HIV incidence and indirectly the HCV incidence. This study aims to assess what would have been the course of the HIV outbreak and its associated economic consequences if the 2009 HCV outbreak had been detected and integrated interventions had been initiated 1- or 2-years earlier.

METHODS

The model was calibrated to reproduce the observed HIV epidemiological and clinical parameters among PWID of Athens, Greece. We examined the effect of the 1- or 2-years earlier detection scenarios, the 1-year later detection, the non-detection scenario, and compared them to the status quo scenario.

RESULTS

Cumulative HIV cases, under the status-quo scenario during 2009-2019, were 1360 (90% Credible intervals: 290, 2470). If the HCV outbreak had been detected 1- or 2- years earlier, with immediate initiation of integrated interventions, 740 and 1110 HIV cases could be averted by 2019, respectively. Regarding the costs, if there was an efficient notification system to detect the HCV outbreak 1 or 2 years earlier, 35.2-53.2 million euros could be saved compared to the status quo by 2019.

CONCLUSIONS

If the HCV outbreak had been detected and promptly addressed, the HIV outbreak would have been prevented and 35.2-53.2 million euros could have been saved.

Risk of HIV Acquisition Among Men Who Have Sex With Men Infected With Bacterial Sexually Transmitted Infections: A Systematic Review and Meta-Analysis

BACKGROUND

Men who have sex with men (MSM) who have bacterial sexually transmitted infections (STIs) are at increased risk for HIV infection. We enhanced and updated past summary risk estimates.

METHODS

We systematically reviewed (PROSPERO No. CRD42018084299) peer-reviewed studies assessing the risk of HIV infection among MSM attributable to Chlamydia trachomatis (CT), Mycoplasma genitalium (MG), Neisseria gonorrhoeae (NG), Treponema pallidum (TP), and/or Trichomonas vaginalis (TV). We searched 3 databases through December 2017. We excluded studies with self-reported data or simultaneous STI and HIV assessment. We conducted dual screening and data extraction, meta-analytically pooled risk ratios (RRs), and assessed potential risk of bias.

RESULTS

We included 26 studies yielding 39 RR (k) for HIV acquisition due to one of TP, NG, or CT. We did not identify eligible data for MG or TV, or for HIV transmission. HIV acquisition risk increased among MSM infected with TP (k = 21; RR, 2.68, 95% confidence interval [CI], 2.00-3.58), NG (k = 11; RR, 2.38; 95% CI, 1.56-3.61), and CT (k = 7; RR, 1.99; 95% CI, 1.59-2.48). Subanalysis RRs for all 3 pathogens were ≥1.66 and remained statistically significant across geography and methodological characteristics. Pooled RR increased for data with the lowest risk of bias for NG (k = 3; RR, 5.49; 95% CI, 1.11-27.05) and TP (k = 4; RR, 4.32; 95% CI, 2.20-8.51). We observed mostly moderate to high heterogeneity and moderate to high risk of bias.

CONCLUSIONS

Men who have sex with men infected with TP, NG, or CT have twice or greater risk of HIV acquisition, although uncertainties exist because of data heterogeneity and risk of bias.