Concurrent partnerships and HIV prevalence disparities by race: linking science and public health practice

Homophily and social mixing in a small community: Implications for infectious disease transmission

Community mixing patterns by sociodemographic traits can inform the risk of epidemic spread among groups, and the balance of in- and out-group mixing affects epidemic potential. Understanding mixing patterns can provide insight about potential transmission pathways throughout a community. We used a snowball sampling design to enroll people recently diagnosed with SARS-CoV-2 in an ethnically and racially diverse county and asked them to describe their close contacts and recruit some contacts to enroll in the study. We constructed egocentric networks of the participants and their contacts and assessed age-mixing, ethnic/racial homophily, and gender homophily. The total size of the egocentric networks was 2,544 people (n = 384 index cases + n = 2,160 recruited peers or other contacts). We observed high rates of in-group mixing among ethnic/racial groups compared to the ethnic/racial proportions of the background population. Black or African-American respondents interacted with a wider range of ages than other ethnic/racial groups, largely due to familial relationships. The egocentric networks of non-binary contacts had little age diversity. Black or African-American respondents in particular reported mixing with older or younger family members, which could increase the risk of transmission to vulnerable age groups. Understanding community mixing patterns can inform infectious disease risk, support analyses to predict epidemic size, or be used to design campaigns such as vaccination strategies so that community members who have vulnerable contacts are prioritized.

Introducing SoNHR-Reporting guidelines for Social Networks In Health Research

OBJECTIVE

The overall goal of this work is to produce a set of recommendations (SoNHR-Social Networks in Health Research) that will improve the reporting and dissemination of social network concepts, methods, data, and analytic results within health sciences research.

METHODS

This study used a modified-Delphi approach for recommendation development consistent with best practices suggested by the EQUATOR health sciences reporting guidelines network. An initial set of 28 reporting recommendations was developed by the author team. A group of 67 (of 147 surveyed) experienced network and health scientists participated in an online feedback survey. They rated the clarity and importance of the individual recommendations, and provided qualitative feedback on the coverage, usability, and dissemination opportunities of the full set of recommendations. After examining the feedback, a final set of 18 recommendations was produced.

RESULTS

The final SoNHR reporting guidelines are comprised of 18 recommendations organized within five domains: conceptualization (how study research questions are linked to network conceptions or theories), operationalization (how network science portions of the study are defined and operationalized), data collection & management (how network data are collected and managed), analyses & results (how network results are analyzed, visualized, and reported), and ethics & equity (how network-specific human subjects, equity, and social justice concerns are reported). We also present a set of exemplar published network studies which can be helpful for seeing how to apply the SoNHR recommendations in research papers. Finally, we discuss how different audiences can use these reporting guidelines.

CONCLUSIONS

These are the first set of formal reporting recommendations of network methods in the health sciences. Consistent with EQUATOR goals, these network reporting recommendations may in time improve the quality, consistency, and replicability of network science across a wide variety of important health research areas.

Mapping Implementation Science with Expert Recommendations for Implementing Change (MIS-ERIC): Strategies to Improve PrEP Use among Black Cisgender Women Living in Mississippi

BACKGROUND

Black women are disproportionately affected by the HIV epidemic. Strategies to increase Black women's use of pre-exposure prophylaxis (PrEP) are needed.

METHODS

Interviews were conducted in Mississippi (MS) with Black, cisgender women at risk for HIV, and community healthcare clinic (CHC) staff who work directly with this population. Reflexive thematic analysis was used to identify barriers and select appropriate implementation strategies to increase PrEP care.

RESULTS

Twenty Black women and twelve CHC staff were interviewed. PrEP use barriers resulted from low HIV risk awareness, lack of PrEP knowledge, and structural and stigma-related barriers. Methods for PrEP education and motivation included normalizing PrEP in public communications, providing education at places where women congregate, and tailoring PrEP content with Black women as educators. The Expert Recommendations for Implementing Change (ERIC) project provides a way for implementation scientists to select strategies that are consistent within research and practice across studies. Strategies from the ERIC project were selected to address implementation barriers.

CONCLUSIONS

Tailoring PrEP implementation protocols to increase Black women's access, engagement, and adherence to PrEP is needed. This is one of the first implementation studies to incorporate these four implementation concepts into a single study: (1) implementation outcomes, (2) i-PARIHS, (3) ERIC's strategy list, and (4) operationalizing the strategies using the Proctor et al., guidelines. Results provide an in-depth comprehensive list of implementation strategies to increase PrEP uptake for Black women in MS.

Improving and Extending STERGM Approximations Based on Cross-Sectional Data and Tie Durations

Temporal exponential-family random graph models (TERGMs) are a flexible class of models for network ties that change over time. Separable TERGMs (STERGMs) are a subclass of TERGMs in which the dynamics of tie formation and dissolution can be separated within each discrete time step and may depend on different factors. The Carnegie et al. (2015) approximation improves estimation efficiency for a subclass of STERGMs, allowing them to be reliably estimated from inexpensive cross-sectional study designs. This approximation adapts to cross-sectional data by attempting to construct a STERGM with two specific properties: a cross-sectional equilibrium distribution defined by an exponential-family random graph model (ERGM) for the network structure, and geometric tie duration distributions defined by constant hazards for tie dissolution. In this paper we focus on approaches for improving the behavior of the Carnegie et al. approximation and increasing its scope of application. We begin with Carnegie et al.'s observation that the exact result is tractable when the ERGM is dyad-independent, and then show that taking the sparse limit of the exact result leads to a different approximation than the one they presented. We show that the new approximation outperforms theirs for sparse, dyad-independent models, and observe that the errors tend to increase with the strength of dependence for dyad-dependent models. We then develop theoretical results in the dyad-dependent case, showing that when the ERGM is allowed to have arbitrary dyad-dependent terms and some dyad-dependent constraints, both the old and new approximations are asymptotically exact as the size of the STERGM time step goes to zero. We note that the continuous-time limit of the discrete-time approximations has the desired cross-sectional equilibrium distribution and exponential tie duration distributions with the desired means. We show that our results extend to hypergraphs, and we propose an extension of the Carnegie et al. framework to dissolution hazards that depend on tie age.

Novel Location-Based Survey Using Cognitive Interviews to Assess Geographic Networks and Hotspots of Sex and Drug Use: Implementation and Validation Study

BACKGROUND

The Ending the HIV Epidemic initiative in the United States relies on HIV hotspots to identify where to geographically target new resources, expertise, and technology. However, interventions targeted at places with high HIV transmission and infection risk, not just places with high HIV incidence, may be more effective at reducing HIV incidence and achieving health equity.

OBJECTIVE

We described the implementation and validation of a web-based activity space survey on HIV risk behaviors. The survey was intended to collect geographic information that will be used to map risk behavior hotspots as well as the geography of sexual networks in Los Angeles County.

METHODS

The survey design team developed a series of geospatial questions that follow a 3-level structure that becomes more geographically precise as participants move through the levels. The survey was validated through 9 cognitive interviews and iteratively updated based on participant feedback until the saturation of topics and technical issues was reached.

RESULTS

In total, 4 themes were identified through the cognitive interviews: functionality of geospatial questions, representation and accessibility, privacy, and length and understanding of the survey. The ease of use for the geospatial questions was critical as many participants were not familiar with mapping software. The inclusion of well-known places, landmarks, and road networks was critical for ease of use. The addition of a Google Maps interface, which was familiar to many participants, aided in collecting accurate and precise location information. The geospatial questions increased the length of the survey and warranted the inclusion of features to simplify it and speed it up. Using nicknames to refer to previously entered geographic locations limited the number of geospatial questions that appeared in the survey and reduced the time taken to complete it. The long-standing relationship between participants and the research team improved comfort to disclose sensitive geographic information related to drug use and sex. Participants in the cognitive interviews highlighted how trust and inclusive and validating language in the survey alleviated concerns related to privacy and representation.

CONCLUSIONS

This study provides promising results regarding the feasibility of using a web-based mapping survey to collect sensitive location information relevant to ending the HIV epidemic. Data collection at several geographic levels will allow for insights into spatial recall of behaviors as well as future sensitivity analysis of the spatial scale of hotspots and network characteristics. This design also promotes the privacy and comfort of participants who provide location information for sensitive topics. Key considerations for implementing this type of survey include trust from participants, community partners, or research teams to overcome concerns related to privacy and comfort. The implementation of similar surveys should consider local characteristics and knowledge when crafting the geospatial components.

Staged HIV transmission and treatment in a dynamic model with long-term partnerships

The transmission dynamics of HIV are closely tied to the duration and overlap of sexual partnerships. We develop an autonomous population model that can account for the possibilities of an infection from either a casual sexual partner or a long-term partner who was either infected at the start of the partnership or has been newly infected since the onset of the partnership. The impact of the long-term partnerships on the rate of infection is captured by calculating the expected values of the rate of infection from these extended contacts. The model includes three stages of infectiousness: acute, chronic, and virally suppressed. We calculate HIV incidence and the fraction of new infections attributed to casual contacts and long-term partnerships allowing for variability in condom usage, the effect of achieving and maintaining viral suppression, and early intervention by beginning HAART during the acute phase of infection. We present our results using data on MSM HIV transmission from the CDC in the U.S. While the acute stage is the most infectious, the majority of the new infections will be transmitted by long-term partners in the chronic stage when condom use is infrequent as is common in long-term relationships. Time series analysis of the solution, as well as parameter sensitivity analysis, are used to determine effective intervention strategies.

Continuous Time Graph Processes with Known ERGM Equilibria: Contextual Review, Extensions, and Synthesis

Graph processes that unfold in continuous time are of obvious theoretical and practical interest. Particularly useful are those whose long-term behavior converges to a graph distribution of known form. Here, we review some of the conditions for such convergence, and provide examples of novel and/or known processes that do so. These include subfamilies of the well-known stochastic actor oriented models, as well as continuum extensions of temporal and separable temporal exponential family random graph models. We also comment on some related threads in the broader work on network dynamics, which provide additional context for the continuous time case. Graph processes that unfold in continuous time are natural models for social network dynamics: able to directly represent changes in structure as they unfold (rather than, e.g. as snapshots at discrete intervals), such models not only offer the promise of capturing dynamics at high temporal resolution, but are also easily mapped to empirical data without the need to preselect a level of granularity with respect to which the dynamics are defined. Although relatively few general frameworks of this type have been extensively studied, at least one (the stochastic actor-oriented models, or SAOMs) is arguably among the most successful and widely used families of models in the social sciences (see, e.g., Snijders (2001); Steglich et al. (2010); Burk et al. (2007); Sijtsema et al. (2010); de la Haye et al. (2011); Weerman (2011); Schaefer and Kreager (2020) among many others). Work using other continuous time graph processes has also found applications both within (Koskinen and Snijders, 2007; Koskinen et al., 2015; Stadtfeld et al., 2017; Hoffman et al., 2020) and beyond (Grazioli et al., 2019; Yu et al., 2020) the social sciences, suggesting the potential for further advances.

Changes in Sexual Behaviors with Opposite-Sex Partners and Sexually Transmitted Infection Outcomes Among Females and Males Ages 15-44 Years in the USA: National Survey of Family Growth, 2008-2019

Rates of reported gonorrhea and chlamydial infections have increased substantially over the past decade in the USA and disparities persist across age and race/ethnicity. We aimed to understand potential changes in sexual behaviors, sexual network attributes, and sexually transmitted infection (STI) screening that may be contributing to these trends. We analyzed data from 29,423 female and 24,605 male respondents ages 15-44 years from the National Survey of Family Growth, 2008-2019. We used survey-weighted linear or logistic regression to evaluate linear temporal trends in sexual behaviors with opposite-sex partners, network attributes, and STI testing, treatment, and diagnosis. Significant declines were observed in condom use at last vaginal sex, mean number of vaginal sex acts, proportion of condom-protected sex acts in the past 4 weeks, and racial/ethnic homophily with current partners among males and females from 2008-2010 through 2017-2019. Among males, mean number of female partners in the past 12 months and concurrency also declined, while the percent reporting ever having sex with another male increased. Past-year testing for chlamydia and any STI increased among females. Research is needed to understand how these changes interact and potentially contribute to increasing reported gonorrhea and chlamydia diagnoses and identify avenues for future intervention.

Does Context and Adversity Shape Sexual Behavior in Youth? Findings from Two Representative Samples of Puerto Rican Youth

Sexual risk behaviors often co-occur. Understanding the heterogeneity in patterns of sexual behavior among youth and how context of majority and minoritized status may be related to these behaviors can inform targeted STIs/HIV interventions. Data are from the Boricua Youth Study, a longitudinal study of two probability samples of Puerto Rican youth recruited in the South Bronx (SBx) and the metropolitan area in Puerto Rico (PR). We identified patterns of sexual behaviors among young adults (ages 15-24) with sexual experience (N = 1,203) using latent class analysis. Analyses examined context differences and the prospective relationship between adverse childhood experiences (ACEs) (childhood maltreatment/violence, family/parental dysfunction) and patterns of sexual behaviors (age at first sex, number of sex partners, sex with a high-risk partner, condom use, sex while intoxicated, oral sex, anal sex). We identified five classes of sexual behaviors: (1) currently inactive (16.51%); (2) single partner, low activity (13.49%); (3) single partner, inconsistent condom use (32.19%); (4) single partner, sex without a condom (27.65%); and (5) multirisk (10.16%). Young adults from the SBx (minoritized context), those who identified as male, and those with higher child maltreatment/violence ACEs were more likely to be in the multi-risk class relative to the single partner, inconsistent condom use class. Those from the SBx were also more likely to be in the single partner, sex without condom class, relative to the single partner, inconsistent condom use class. Differences in young adults' patterns of sexual behaviors between the two contexts, one representing the minoritized context (SBx) contrasted to the majority context (PR), were not explained by ACEs. Findings highlight the heterogeneity in the patterns of sexual behaviors among Puerto Rican young adults as well as how such patterns vary based on sociocultural contexts. Exposure to child maltreatment/violence ACEs was related to the riskier patterns; however, they did not explain why riskier patterns of sexual behaviors were found in the SBx compared to PR. Results underscore the need for tailored interventions and more in-depth examination of differences across contexts.

Vil NM, Bond KT, Mitchell JW, Juarez AC, Lambert F, Muheriwa SR, McMahon J. Dimensions of Sexual Health Conversations among U.S. Black Heterosexual Couples

Sexual health communication is an important feature of healthy intimate relationships; however, some couples may avoid discussing difficult matters (e.g., HIV/STI testing, sexual satisfaction) to minimize interpersonal conflict. From October 2018 to May 2019 in New York State, we conducted a multi-method descriptive pilot study to characterize Black heterosexual couples' (N = 28) sexual health conversations. Partners individually completed an online sexual health/relationship survey before engaging in-person for a joint dyadic qualitative in-depth interview. Quantitative descriptive statistics demonstrated that most absolute score differences among couple's preferences for sexual health outcomes, communal coping and sexual relationship power were mainly small, but greatest regarding extra-dyadic sexual behaviors. A qualitative descriptive approach discerned, motivation and norms for sexual health conversations, and communication patterns. Thematic and content analysis revealed two central themes: initiating and sustaining sexual health conversations, and leveraging features of the couples to promote sexual health. Integrated findings indicate that couples possess varied communication patterns that operate with motivations for sexual health conversations toward subsequent sexual health promotion. Equitable and skewed communication patterns emerged as relationship assets that can be leveraged to optimize sexual health. There is also opportunity for future work to address communication regarding extra-dyadic behavior and preferences. Asset-based considerations are discussed.

Comparing Sexual Network Mean Active Degree Measurement Metrics Among Men Who Have Sex With Men

BACKGROUND

Mean active degree is an important proxy measure of cross-sectional network connectivity commonly used in HIV/sexually transmitted infection epidemiology research. No current studies have compared measurement methods of mean degree using a cross-sectional study design for men who have sex with men (MSM) in the United States. We compared mean degree estimates based on reported ongoing main and casual sexual partnerships (current method) against dates of first and last sex (retrospective method).

METHODS

We used data from ARTnet, a cross-sectional survey of MSM in the United States (2017-2019). ARTnet collected data on the number and types of sexual partners in the past year, limited to the 5 most recent partners (data truncation). We quantified partnerships for months 0 to 12 before the survey date (retrospective method) and compared that with ongoing partnerships on the day of survey (current method). We used linear regression to understand the impact of truncated partnership data on mean degree estimation.

RESULTS

The retrospective method yielded similar degree estimates to the current for months proximate to the day of survey. The retrospective method mean degree systematically decreased as the month increased from 0 to 12 months before survey date. This was driven by data truncation: among participants with >5 partners in the past year compared with those with ≤5, the average change in main partnership degree between 12 and 0 months before survey date was -0.05 (95% confidence interval, -0.08 to -0.03) after adjusting for race/ethnicity, age, and education. The adjusted average change in casual partnership degree was -0.40 (95% confidence interval, -0.45 to -0.35).

CONCLUSIONS

The retrospective method underestimates mean degree for MSM in surveys with truncated partnership data, especially for casual partnerships. The current method is less prone to bias from partner truncation when the target population has high rate of partners per year.

Sexual Behavior and Health From Adolescence to Adulthood: Illustrative Examples of 25 Years of Research From Add Health

Due to its long-term longitudinal design, the National Longitudinal Study of Adolescent to Adult Health (Add Health) has provided numerous valuable insights into adolescent and young adult sexual behavior. Framed by a conceptual model of sexual behavior and health, I review research using Add Health data to study sexual behavior and health. In this paper, I review research examining both predictors (e.g., neighborhood, family, genetic, individual) and health outcomes (e.g., sexually transmitted infections, mental health) of sexual behavior in adolescents and young adults. Where possible, I focus on long-term longitudinal studies that make use of the unique strengths of the Add Health data. Existing Add Health research has provided considerable information about both the predictors and health consequences of adolescent and young adult sexual behavior. Factors ranging from neighborhoods to genetics predict whether adolescent and young adults engage in sexual behaviors. Findings on long-term outcomes of adolescent sexual behavior suggest that early sexual behavior predicts higher rates of sexually transmitted infections and pregnancy in young adulthood, but not long-term changes to mental health. Unique contributions of Add Health include the ability to examine multidimensional bio-ecological predictors of sexual behavior and to examine long-term effects of sexual behavior and how sexual behaviors and their correlates change across adolescence into adulthood. Future work can leverage these strengths, and in particular the long-term longitudinal nature of the data, to uncover new insights about the developmental course of sexual behavior and health.

Effects of the Waya Intervention on Marital Satisfaction and HIV Risk Behaviors in Western Kenya: A Pre-Post Study Design

Poor marital satisfaction is associated with high-risk sexual behavior and HIV transmission. We tested whether a counselor-led couple education and counseling intervention dubbed Waya (paternal aunt) would improve marital satisfaction and reduce HIV risk behavior among married couples in Kisumu County, western Kenya. In a pre-post design, we enrolled 60 heterosexual married couples at high risk for HIV to undergo five 1-h couple education and counseling sessions over 56 days. We collected self-reported data on marital satisfaction, the number of sex partners, and condom use with extramarital partners at pre- and post-intervention visits. We used Wilcoxon and McNemar tests to examine the association of our intervention with marital relationship satisfaction and reduction in HIV risk sexual behavior. The intervention was associated with marital relationship satisfaction score improvement from a median of 5 (interquartile range [IQR], 4-5) to 6 (IQR, 6-7) among men and 4 (IQR, 3-5) to 6 (IQR, 5-6) among women (p < .01). The intervention was also associated with reducing HIV risk sexual behaviors depicted by a reduction in the number of sex partners in the past one month and an increase in consistent extramarital condom use. The number of sex partners reduced from a median of 2 (IQR, 1-2) to 1 (IQR, 1-2) and consistent extramarital condom use increased from 4% at baseline to 56% among men. Our intervention was associated with improvements in marital relationship satisfaction and reductions in HIV high-risk behaviors necessary for achieving epidemic control in HIV hotspots such as fishing communities in western Kenya.

Variations in sexual network connectivity may explain dramatic variations in sexually transmitted infection prevalence between populations and over time: a selected four-country analysis

Background: The incidence of sexually transmitted infections (STIs) has been noted to vary dramatically between population groups and over time. Here, the hypothesis that changes in network connectivity underpin these changes is explored.

Methods: The incidence/prevalence estimates of HIV, herpes simplex virus-2, syphilis, chlamydia, and gonorrhoea, as well as two markers of sexual network connectivity (partner concurrency and multiple partnering) by ethnic group and sexual orientation in Kenya, South Africa, the United Kingdom (UK) and the United States (USA) were extracted from published studies. Pearson’s correlation was used to test the association between the markers of network connectivity and the incidence/prevalence of these five STIs. A literature review was performed to evaluate the possible causes of the increases and decreases in syphilis incidence over the past 60 years.

Results: In each country, the five STIs were found to cluster in particular ethnic groups and sexual orientations and to be positively associated with the two markers of network connectivity. Syphilis incidence in the UK and USA was found to increase dramatically in the 1960s/1970s, decline in the 1980s and again increase in the late 1990s. These changes took place predominantly in men who have sex with men, and were preceded by corresponding changes in network connectivity. The large decline in antenatal syphilis prevalence in Kenya and South Africa in the 1990s were likewise preceded by declines in network connectivity.

Conclusions: Although other explanatory variables are not controlled for, the present analysis is compatible with the hypothesis that differential network connectivity is a parsimonious explanation for variations in STI incidence over time and between populations.

Intersectional invisibility experiences of low-income African-American women in healthcare encounters

BACKGROUND

The disparities that Black/African-American women experience in health care are persistent and staggering. Findings from health outcomes research continue to demonstrate poorer outcomes for African-American women compared to women of other race/ethnicity in several conditions. These racial/ethnic and gender health disparities observed are complex, heavily nuanced and multi-factorial. To understand these, there is a need to apply an 'intersectionality' lens. Intersectionality refers to the experience of persons with multiple intersecting statuses. The objective of this exploratory study was to gain insight into the healthcare experiences of low-income African-American women.

METHODS

In-depth one-on-one interviews were conducted with 22 women and 2 focus group discussions with community leaders and advocates. Investigators conducted a thematic analysis of the transcripts.

RESULTS

The thematic analysis revealed four major themes, which tell the story of the intersectional invisibility experienced by low-income AA women in the healthcare system. These included (1) the perception of 'not feeling heard'; (2) patient as 'expert of her own body'; (3) disregard of patient preferences; and (4) the need for self-advocacy.

CONCLUSIONS

Black/African-American women, and particularly those with socioeconomic disadvantage, experience intersectional invisibility resulting from provider implicit bias, stereotypical assumptions, and systemic structures that enable discriminatory practices in healthcare delivery. Healthcare provider education that more explicitly addresses these biases and stereotypes should be complemented with system-level interventions that aim to dismantle the structural racism inherent in healthcare policies and practices.

Associations of Social Network- and Individual-Level Factors with HIV Testing, Condom Use, and Interest in PrEP Among Young Black Women

To achieve the 2030 goal of ending the HIV epidemic, we must consider social network- along with individual-level factors related to HIV prevention among young Black women (YBW). This cross-sectional study examined egocentric social network- and individual-level data of 180 YBW aged 18-24. Multivariable logistic regression models were used to study social network characteristics and individual sexual behaviors related to HIV prevention behaviors (e.g., HIV testing, condom use, and interest in preexposure prophylaxis, or PrEP). On average, YBW nominated 11 social network members (SNMs; seven friends, two family members, and one sex partner). About 92% of YBW spoke to at least one SNM about condom use and 58% spoke to at least one SNM about HIV testing. Respondents who spoke to a sex partner about condom use had 70% lower odds of being interested in PrEP, but 2.99 times the odds of reporting condom use during last sex. Odds of being tested for HIV in the prior 3 months were significantly increased by 3.97 times for those who spoke to at least one sex partner about HIV testing. However, odds of being interested in PrEP were significantly decreased by 63% for YBW who were tested for HIV in the prior 3 months. Findings underscore that understanding network- and individual-level factors is crucial in increasing HIV testing, condom use, and interest in PrEP among YBW.

Health Locus of Control and Neurocognitive Function in Latinx and Non-Latinx White People Living With HIV: A Cross-sectional Study

ABSTRACT

Research suggests that health locus of control (HLOC) is related to important health and neurocognitive outcomes in people living with HIV. However, the role of ethnicity in these relationships remains poorly understood. This study explored the role of HLOC on neurocognition in a diverse sample of 134 people living with HIV (Latinx: n = 96; non-Latinx White: n = 38) who completed comprehensive neurocognitive evaluations and the Multidimensional HLOC Scale-Form C. Results indicate no ethnocultural differences in HLOC beliefs (ps > .05). External HLOC (i.e., chance and powerful others) related to worse neurocognition in the Latinx group and contributed to significant variance in global neurocognition and learning, memory, and verbal fluency, underscoring the role of external HLOC beliefs on neurocognition, particularly for Latinx individuals. Additional research is needed to better characterize the mechanistic relationship between HLOC beliefs and neurocognitive function and to further explore this relationship among other underrepresented populations also disproportionately affected by HIV.

Impact of Survey Design on Estimation of Exponential-Family Random Graph Models from Egocentrically-Sampled Data

Egocentric sampling of networks selects a subset of nodes ("egos") and collects information from them on themselves and their immediate network neighbours ("alters"), leaving the rest of the nodes in the network unobserved. This design is popular because it is relatively inexpensive to implement and can be integrated into standard sample surveys. Recent methodological developments now make it possible to statistically analyse this type of network data with Exponential-family Random Graph Models (ERGMs). This provides a framework for principled statistical inference, and the fitted models can in turn be used to simulate complete networks of arbitrary size that are consistent with the observed sample data, allowing one to infer the distribution of whole-network properties generated by the observed egocentric network statistics. In this paper, we discuss how design choices for egocentric network studies impact statistical estimation and inference for ERGMs. The design choices include both measurement strategies (for ego and alter attributes, and for ego-alter and alter-alter ties) and sampling strategies (for egos and alters). We discuss the importance of harmonising measurement specifications across egos and alters, and conduct simulation studies to demonstrate the impact of sampling design on statistical inference, specifically stratified sampling and degree censoring.

Psychosocial Support, Sexual Health, and HIV Risk among Older Men Who Have Sex with Younger Men

This study examines the extent to which older males are willing to offer psychosocial and sexual health promoting support to their younger male partners, as well as the individual and relationship-level factors associated with this willingness to provide support. In total, 324 men over the age of 45, who currently or previously had younger male sexual partners, completed an anonymous online survey. Results show that participants were most willing to provide emotional support to their younger male partners, followed by health-related encouragement, HIV/STI testing support, and financial support. Of note, HIV positive status and being in a "main partnership" were associated with greater willingness to provide financial support. These results suggest that older men are willing to provide psychosocial and health promotive support to younger male partners, which could be leveraged in targeted interventions to reduce HIV transmission.

Sorting by Race/Ethnicity Across HIV Genetic Transmission Networks in Three Major Metropolitan Areas in the United States

An important component underlying the disparity in HIV risk between race/ethnic groups is the preferential transmission between individuals in the same group. We sought to quantify transmission between different race/ethnicity groups and measure racial assortativity in HIV transmission networks in major metropolitan areas in the United States. We reconstructed HIV molecular transmission networks from viral sequences collected as part of HIV surveillance in New York City, Los Angeles County, and Cook County, Illinois. We calculated assortativity (the tendency for individuals to link to others with similar characteristics) across the network for three candidate characteristics: transmission risk, age at diagnosis, and race/ethnicity. We then compared assortativity between race/ethnicity groups. Finally, for each race/ethnicity pair, we performed network permutations to test whether the number of links observed differed from that expected if individuals were sorting at random. Transmission networks in all three jurisdictions were more assortative by race/ethnicity than by transmission risk or age at diagnosis. Despite the different race/ethnicity proportions in each metropolitan area and lower proportions of clustering among African Americans than other race/ethnicities, African Americans were the group most likely to have transmission partners of the same race/ethnicity. This high level of assortativity should be considered in the design of HIV intervention and prevention strategies.

Heterosexual Cisgender Men Partnered with Transgender Women Exhibit Higher HIV/STI Sexual Risk than Their Gay, Bisexual, and Queer Counterparts: Findings from a U.S.-Based Convenience Sample Recruited Online

Cisgender men are frequently vectors for HIV transmission among transgender women. Despite this, the correlates of sexual risk among these men remain under-examined. The purpose of the present study was to explore potential differences in relationship characteristics, sexual risk-taking, and risk-reduction strategies among cisgender men partnered with transgender women. The study utilized secondary screening data provided by adult cis men who reported being in a primary relationship with a trans woman (N = 710). Gay men (18%) were comparatively older, and most likely to report both HIV seropositivity and committed pairings. Heterosexual men (14%) were more likely to report exchange sex, briefer relationships, extra-dyadic sex, lesser serostatus awareness or PrEP uptake. Queer men (7%) were youngest, and most likely to access PrEP. Heterosexual cis men with trans women partners may be subject to unique socio-cultural drivers of sexual risk, such as heteronormative pressures and relationship stigma.

HIV and Sexually Transmitted Infection Epidemic Potential of Networks of Men Who Have Sex With Men in Two Cities

BACKGROUND

The speed with which a pathogen circulates in a sexual network is a function of network connectivity. Cross-sectional connectivity is a function of network features like momentary degree and assortative mixing. Temporal connectivity is driven by partner acquisition rates. The forward-reachable path (FRP) has been proposed as a summary measure of these two aspects of transmission potential. We use empirical data from San Francisco and Atlanta to estimate the generative parameters of the FRP and compare results to the HIV/sexually transmitted infection epidemics in each city.

METHODS

We used temporal exponential random graph models to estimate the generative parameters for each city's dynamic sexual network from survey data. We then simulated stochastic dynamic networks from the fitted models and calculated the FRP for each realization, overall, and stratified by partnership type and demographics.

RESULTS

The overall mean and median paths were higher in San Francisco than in Atlanta. The overall paths for each city were greater than the sum of the paths in each individual partnership network. In the casual partnership network, the mean path was highest in the youngest age group and lowest in the oldest age group, despite the fact that the youngest group had the lowest mean momentary degree and past-year partner counts.

CONCLUSIONS

The FRP by age group revealed the additional utility of the measure beyond the temporal and cross-sectional network connectivity measures. Other nonnetwork factors are still necessary to infer total epidemic potential for any specific pathogen.

Concurrency measures in the era of temporal network epidemiology: a review

Diseases spread over temporal networks of interaction events between individuals. Structures of these temporal networks hold the keys to understanding epidemic propagation. One early concept of the literature to aid in discussing these structures is concurrency-quantifying individuals' tendency to form time-overlapping 'partnerships'. Although conflicting evaluations and an overabundance of operational definitions have marred the history of concurrency, it remains important, especially in the area of sexually transmitted infections. Today, much of theoretical epidemiology uses more direct models of contact patterns, and there is an emerging body of literature trying to connect methods to the concurrency literature. In this review, we will cover the development of the concept of concurrency and these new approaches.

Partnership dynamics in mathematical models and implications for representation of sexually transmitted infections: a review

Mathematical models of sexually transmitted disease (STI) are increasingly relied on to inform policy, practice, and resource allocation. Because STI transmission requires sexual contact between two or more people, a model's ability to represent the dynamics of sexual partnerships can influence the validity of findings. This ability is to a large extent constrained by the model type, as different modeling frameworks vary in their capability to capture patterns of sexual contact at individual, partnership, and network levels. In this paper, we classify models into three groups: compartmental, individual-based, and statistical network models. For each framework, we describe the basic model structure and discuss key aspects of sexual partnership dynamics: how and with whom partnerships are formed, partnership duration and dissolution, and temporal overlap in partnerships (concurrency). We illustrate the potential implications of accurately accounting for partnership dynamics, but these effects depend on characteristics of both the population and pathogen; the combined impact of these partnership and epidemiologic dynamics can be difficult to predict. While each of the reviewed model frameworks may be appropriate to inform certain research or policy questions, modelers and consumers of models should carefully consider the implications of sexual partnership dynamics for the questions under study.

Assessment of Bias in Estimates of Sexual Network Degree using Prospective Cohort Data

BACKGROUND

Sexual network degree, a count of ongoing partnerships, plays a critical role in the transmission dynamics of human immunodeficiency virus and other sexually transmitted infections. Researchers often quantify degree using self-reported cross-sectional data on the day of survey, which may result in bias because of uncertainty about future sexual activity.

METHODS

We evaluated the bias of a cross-sectional degree measure with a prospective cohort study of men who have sex with men (MSM). At baseline, we asked men about whether recent sexual partnerships were ongoing. We confirmed the true, ongoing status of those partnerships at baseline at follow-up. With logistic regression, we estimated the partnership-level predictors of baseline measure accuracy. With Poisson regression, we estimated the longitudinally confirmed degree as a function of baseline predicted degree.

RESULTS

Across partnership types, the baseline ongoing status measure was 70% accurate, with higher negative predictive value (91%) than positive predictive value (39%). Partnership exclusivity and racial pairing were associated with higher accuracy. Baseline degree generally overestimated confirmed degree. Bias, or number of ongoing partners different than predicted at baseline, was -0.28 overall, ranging from -1.91 to -0.41 for MSM with any ongoing partnerships at baseline. Comparing MSM of the same baseline degree, the level of bias was stronger for black compared with white MSM, and for younger compared with older MSM.

CONCLUSIONS

Research studies may overestimate degree when it is quantified cross-sectionally. Adjustment and structured sensitivity analyses may account for bias in studies of human immunodeficiency virus or sexually transmitted infection prevention interventions.

Development of a Mathematical Model to Estimate the Cost-Effectiveness of HRSA's Ryan White HIV/AIDS Program

BACKGROUND

The Health Resources and Services Administration's Ryan White HIV/AIDS Program provides services to more than half of all people diagnosed with HIV in the United States. We present and validate a mathematical model that can be used to estimate the long-term public health and cost impact of the federal program.

METHODS

We developed a stochastic, agent-based model that reflects the current HIV epidemic in the United States. The model simulates everyone's progression along the HIV care continuum, using 2 network-based mechanisms for HIV transmission: injection drug use and sexual contact. To test the validity of the model, we calculated HIV incidence, mortality, life expectancy, and lifetime care costs and compared the results with external benchmarks.

RESULTS

The estimated HIV incidence rate for men who have sex with men (502 per 100,000 person years), mortality rate of all people diagnosed with HIV (1663 per 100,000 person years), average life expectancy for individuals with low CD4 counts not on antiretroviral therapy (1.52-3.78 years), and lifetime costs ($362,385) all met our validity criterion of within 15% of external benchmarks.

CONCLUSIONS

The model represents a complex HIV care delivery system rather than a single intervention, which required developing solutions to several challenges, such as calculating need for and receipt of multiple services and estimating their impact on care retention and viral suppression. Our strategies to address these methodological challenges produced a valid model for assessing the cost-effectiveness of the Ryan White HIV/AIDS Program.

Addressing sexually transmitted infections in the sociocultural context of black heterosexual relationships in the United States

RATIONALE

Black girls and women are disproportionately affected by sexually transmitted infections (STIs) and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Research shows sexual networks, sexual concurrency, and assortative mixing impacting racial disparities in STI/HIV. However, the underlying sociocultural conditions of these phenomenon have yet to be fully explored within a framework of Black girls' and women's sexual development.

OBJECTIVE

This grounded theory study investigated the sociocultural conditions and processes of becoming a sexual Black woman in order to understand the sociocultural drivers of STI/HIV rates among this group.

METHOD

We used theoretical sampling to select and interview 20 Black women aged 19-62 years old from a Midwestern community.

RESULTS

This study revealed sociocultural conditions related to Black heterosexual relationships and STI/HIV risk. Protecting Black men, silencing Black girls and women, cultural norms and messaging about sexuality, and gendered societal expectations and sexual stereotypes contribute to STI/HIV risk in Black girls and women.

CONCLUSIONS

Our findings demonstrate how the intersection of social and systemic structures (i.e.,history, incarceration, unemployment) shape the context of Black heterosexual relationships. We suggest STI/HIV prevention efforts address these systemic, cultural, and societal factors in order to effectively reduce racial disparities in STI/HIV risk.

Estimating Contextual Effects from Ego Network Data

Network concepts are often used to characterize the features of a social context. For example, past work has asked if individuals in more socially cohesive neighborhoods have better mental health outcomes. Despite the ubiquity of use, it is relatively rare for contextual studies to employ the methods of network analysis. This is the case, in part, because network data are difficult to collect, requiring information on all ties between all actors. This paper asks whether it is possible to avoid such heavy data collection while still retaining the best features of a contextual-network study. The basic idea is to apply network sampling to the problem of contextual models, where one uses sampled ego network data to infer the network features of each context, and then uses the inferred network features as second-level predictors in a hierarchical linear model. We test the validity of this idea in the case of network cohesion. Using two complete datasets as a test, we find that ego network data are sufficient to capture the relationship between cohesion and important outcomes, like attachment and deviance. The hope, going forward, is that researchers will find it easier to incorporate holistic network measures into traditional regression models.

Correlates of Sexually Transmitted Infections Among South African Women Using Individual- and Community-Level Factors: Results from Generalized Additive Mixed Models

South Africa has the highest burden of human immunodeficiency virus (HIV) infections in the world. There is also growing evidence that an individual's risk of contracting HIV is increased by the presence of other sexually transmitted infections (STIs). The primary objective of this study was to examine the association between the prevalence of STIs in a cohort of South African women who enrolled in HIV prevention trials (2002-2012). The current study linked the individual factors with the community-level characteristics using geo-referencing. These multi-level data were analyzed in generalized additive mixed models settings. In the multivariate logistic regression model, younger age (odds ratio [OR] 4.30, 95% CI 3.20, 5.77 and OR 2.72, 95% CI 2.02, 3.66 for age < 25 and 25-29, respectively); being single/not cohabiting (OR 4.57, 95% CI 3.18, 6.53), two + sex partners (OR 1.46, 95% CI 1.18,1.80); parity < 2 (OR 2.04, 95% CI 1.53, 2.72), parity = 2 (OR 1.85, 95% CI 1.37, 2.48), and using injectables (contraceptive) (OR 1.53, 95% CI 1.13, 2.06) were all significantly associated with increased prevalence of STIs. Women who resided in the communities with high proportions of female headed-households were also significantly at higher risk for STIs (OR 1.20, p = .0025). Because these factors may reflect characteristics of the larger groups who share similar cultural norms and social environments, they can provide considerable insight into the spread of STIs. Prevention strategies based on individual and community-level drivers of STIs are likely to be the most effective means of targeting and reaching those at greatest risk of infection. This strategy has the potential to play a significant role in the epidemic's trajectory.

Automated image analysis of instagram posts: Implications for risk perception and communication in public health using a case study of #HIV

People’s perceptions about health risks, including their risk of acquiring HIV, are impacted in part by who they see portrayed as at risk in the media. Viewers in these cases are asking themselves “do those portrayed as at risk look like me?” An accurate perception of risk is critical for high-risk populations, who already suffer from a range of health disparities. Yet, to date no study has evaluated the demographic representation of health-related content from social media. The objective of this case study was to apply automated image recognition software to examine the demographic profile of faces in Instagram posts containing the hashtag #HIV (obtained from January 2017 through July 2018) and compare this to the demographic breakdown of those most at risk of a new HIV diagnosis (estimates of incidence of new HIV diagnoses from the 2017 US Centers for Disease Control HIV Surveillance Report). We discovered 26,766 Instagram posts containing #HIV authored in American English with 10,036 (37.5%) containing a detectable human face with a total of 18,227 faces (mean = 1.8, standard deviation [SD] = 1.7). Faces skewed older (47% vs. 11% were 35–39 years old), more female (41% vs. 19%), more white (43% vs. 26%), less black (31% vs 44%), and less Hispanic (13% vs 25%) on Instagram than for new HIV diagnoses. The results were similarly skewed among the subset of #HIV posts mentioning pre-exposure prophylaxis (PrEP). This disparity might lead Instagram users to potentially misjudge their own HIV risk and delay prophylactic behaviors. Social media managers and organic advocates should be encouraged to share images that better reflect at-risk populations so as not to further marginalize these populations and to reduce disparity in risk perception. Replication of our methods for additional diseases, such as cancer, is warranted to discover and address other misrepresentations.

Community and Socioeconomic Factors Associated with COVID-19 in the United States: Zip code level cross sectional analysis

BACKGROUND

Multiple reports have pointed towards involvement of community and socioeconomic characteristics of people in the United States may be associated with COVID-19 cases and deaths.

METHODS

In this study, zip-code level data from 5 major metropolitan areas, was utilized to study the effect of multiple demographic & socio-economic factors including race, age, income, chronic disease comorbidity, population density, number of people per household on number of positive cases and ensuing death. Adjusted linear regression analysis using 13 to 16 such variables was performed.

RESULTS

Overall, 442 zip codes reporting 93,170 positive COVID-19 cases and 138 zip codes reporting mortality ranging from 0 to 25 were included in this study. A multivariable linear regression model noted that 1% increase in the proportion of residents above the age of 65 years, proportion of African American residents, proportion of females, persons per household and population density of the zip code increased the proportion of positive cases by 0.77%, 0.23%, 1.64%, 1.83% and 0.46% respectively (P<0.01) with only population density remaining significant in zip codes with greater than median number of cases. In zips with greater than median number of deaths, no community/socio-economic factor contributed significantly to death.

CONCLUSION

This study gives early signals of gender, and racial inequalities while providing overwhelming evidence of how population density may contribute to an increase in the number of positive cases of COVID-19.

Characterizing Men Who Have Sex with Transgender Women in Lima, Peru: Sexual Behavior and Partnership Profiles

HIV prevalence is high among transgender women (TW), but how HIV is transmitted to this population is not well understood. This analysis aims to characterize sexual partners of TW (PTW) to understand how their behavior contributes to HIV risk among TW. We examined baseline data from TW, PTW, and men who have sex with men (MSM) from a treatment-as-prevention study in Lima, Peru. Individual and partnership characteristics were compared across groups, and Poisson regression was used to calculate prevalence ratios for associations between sexual concurrency and potential correlates. We found that 81% of PTW had no cisgender male partners. Prevalence of alcohol dependency, concurrency, and condomless anal intercourse was high and HIV testing was low compared to the other groups. Our results suggest that PTW are a distinct population from MSM and TW, engage in behavior associated with HIV transmission, and are likely not well reached by HIV prevention interventions.

A qualitative study of attitudes towards, typologies, and drivers of concurrent partnerships among people of black Caribbean ethnicity in England and their implications for STI prevention

BACKGROUND

Partner concurrency, (having sexual partnerships overlapping in time), especially when condoms are not used, can facilitate sexually transmitted infections (STI) transmission. In Britain, STI diagnoses rates and the reporting of concurrency are higher among black Caribbeans than other ethnic groups. We explored attitudes towards, drivers, characteristics, and contexts of concurrent partnerships, and their implications for STI risk among black Caribbeans in England.

METHODS

Purposive sampling, by sex and age-groups, was used to recruit participants (overall n = 59) from five sexual health clinics and community settings in London and Birmingham, England. Audio-recorded four focus group discussions (n = 28 participants), and in-depth interviews (n = 31) were conducted (June 2014-December 2015). Transcribed data were thematically analysed using Framework Analysis.

RESULTS

'Main plus' and 'non-main' concurrency were identified in this population. Main plus concurrency involves an individual having a main partner with whom s/he has a "relationship" with, and the individual and/or their partner secretly or explicitly have other non-main partners. In contrast, non-main concurrency entails having multiple, non-committed partners overlapping in time, where concurrency is usually taken as a given, making disclosure to partners irrelevant. While main partnerships were usually long-term, non-main partnerships ranged in duration from a single event through to encounters lasting several months/years. Condomless sex was common with ex/long-term/married/cohabiting partners; whereas condoms were typically used with non-main partners. However, condom use declined with partnership duration and familiarity with partners. Awareness of partners' concurrency facilitated condom use, STI-testing, and partner notification. While unresolved feelings, or sharing children with ex-partners, usually facilitated main plus concurrency; non-main concurrency was common among young, and single people. Gender norms, notions of masculinity, and sexual desires influenced concurrency. Black Caribbean popular music, social media, peer pressure, and relationship norms among black Caribbeans were also perceived to encourage concurrency, especially among men and young people.

CONCLUSIONS

Concurrency among black Caribbeans is shaped by a complex interaction between emotional/psychological, interpersonal, sociocultural, and structural factors. Concurrency type, its duration, and awareness influence sexual health choices, and thus STI risk in this population. Collecting these data during clinic consultations could facilitate offering partner notification methods tailored to concurrency type. Gender- and age-specific, culturally-sensitive interventions addressing STI risks associated with concurrency are needed.

Egocentric sexual networks of men who have sex with men in the United States: Results from the ARTnet study

In this paper, we present an overview and descriptive results from one of the first egocentric network studies of men who have sex with men (MSM) from across the United States: the ARTnet study. ARTnet was designed to support prevention research for human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs) that are transmitted across partnership networks. ARTnet implemented a population-based egocentric network study design that sampled egos from the target population and asked them to report on the number, attributes, and timing of their sexual partnerships. Such data provide the foundation needed for parameterizing stochastic network models that are used for disease projection and intervention planning. ARTnet collected data online from 2017 to 2019, with a final sample of 4904 participants who reported on 16198 sexual partnerships. The aims of this paper were to characterize the joint distribution of three network parameters needed for modeling: degree distributions, assortative mixing, and partnership age, with heterogeneity by partnership type (main, casual and one-time), demography, and geography. Participants had an average of 1.19 currently active partnerships ("mean degree"), which was higher for casual partnerships (0.74) than main partnerships (0.45). The mean rate of one-time partnership acquisition was 0.16 per week (8.5 partners per year). Main partnerships lasted 272.5 weeks on average, while casual partnerships lasted 133.0 weeks. There was strong but heterogenous assortative mixing by race/ethnicity for all groups. The mean absolute age difference for all partnership types was 9.5 years, with main partners differing by 6.3 years compared to 10.8 years for casual partners. Our analysis suggests that MSM may be at sustained risk for HIV/STI acquisition and transmission through high network degree of sexual partnerships. The ARTnet network study provides a robust and reproducible foundation for understanding the dynamics of HIV/STI epidemiology among U.S. MSM and supporting the implementation science that seeks to address persistent challenges in HIV/STI prevention.

Role of Structural Marginalization, HIV Stigma, and Mistrust on HIV Prevention and Treatment Among Young Black Latinx Men Who Have Sex with Men and Transgender Women: Perspectives from Youth Service Providers

Young black and Latinx men who have sex with men (YBLMSM) and transgender women (YBLTW) are disproportionately impacted by HIV. Structural and social marginalization, the social barriers, and structures that unevenly distribute benefits and burdens to different groups, may contribute to inability for youth to access prevention and treatment care services. Yet, few reports have examined the community and health care experiences of social marginalization among youth service providers who have multiple roles in the community (i.e., serve as a service provider and are a member or prior member of the YBLMSM and YBLTW population). Eighteen key informants (KIs), defined as youth, young adults, or adults who were members of or connected to the YBLMSM and young black and Latinx transgender (YBLTG) community, participated in a one-time, face-to-face, or telephone key informant interview (KII) lasting ∼45 min. KIs were defined as youth service providers because they described working with the target population and either being a member of or closely connected to the target population. KIs described key themes related to marginalization: lack of competent care among health care providers and both clinical and community spaces that left out key populations. HIV stigma and medical mistrust continues to create a barrier to care in this population and for interventions to be effective interventions will need to use an intersectional approach that simultaneously address all identities, and the social and structural needs of youth.

No Evidence of Bias in Sexual Partnership Corroboration by Race and Ethnicity Among a Diverse Cohort of Young Men Who Have Sex with Men and Transgender Women

Black men who have sex with men (MSM) continue to experience disproportionately high HIV incidence rates relative to their white peers. Yet, Black MSM do not report higher levels of sexual risk behavior, and contextual factors such as access to care and sexual networks only partially explain these disparities. However, risk misclassification could help explain this paradox, if measurement biases systematically underestimate sexual risk behavior among Black MSM relative to their peers. The current study examined variation in sexual partnership corroboration in the RADAR study, a large and diverse cohort of young MSM and transgender women. Network data were elicited regarding all sexual partners in the prior 6 months, including instances where participants reported other participants as sexual partners. Using these data, anal and condomless anal sex partners were separately examined using a series of exponential random graph models to estimate the rate of corroboration of sexual connections between participants and examine whether this parameter varied by race/ethnicity. For both types of behavior, providing separate estimates for corroboration across race/ethnicity groups reduced model fit and did not significantly vary across groups. Accordingly, we found no evidence of measurement bias by race/ethnicity in the current data. However, overall rates of corroboration (41.2-50.3%) were low, suggesting substantial levels of measurement error. Accordingly, it is vital that researchers continue to improve upon methods to measure risk behavior in order to maximize their validity. We discuss the implications of these findings, including potential alternative causes of risk misclassification (e.g., sampling bias) and future directions to reduce measurement error.

Social Space Diffusion: Applications of a Latent Space Model to Diffusion with Uncertain Ties

Social networks represent two different facets of social life: (1) stable paths for diffusion, or the spread of something through a connected population, and (2) random draws from an underlying social space, which indicate the relative positions of the people in the network to one another. The dual nature of networks creates a challenge - if the observed network ties are a single random draw, is it realistic to expect that diffusion only follows the observed network ties? This study takes a first step towards integrating these two perspectives by introducing a social space diffusion model. In the model, network ties indicate positions in social space, and diffusion occurs proportionally to distance in social space. Practically, the simulation occurs in two parts. First, positions are estimated using a statistical model (in this example, a latent space model). Then, second, the predicted probabilities of a tie from that model - representing the distances in social space - or a series of networks drawn from those probabilities - representing routine churn in the network - are used as weights in a weighted averaging framework. Using longitudinal data from high school friendship networks, I explore the properties of the model. I show that the model produces smoothed diffusion results, which predict attitudes in future waves 10% better than a diffusion model using the observed network, and up to 5% better than diffusion models using alternative, non-model-based smoothing approaches.

Coital Frequency and Male Concurrent Partnerships During Pregnancy and Postpartum in Agbogbloshie, Ghana

During pregnancy and postpartum, women in high HIV prevalence regions continue to be at high risk for acquiring HIV, due to both behavioral and biological mechanisms, despite declines in coital frequency as a pregnancy advances. We estimated differences in rates of partnership concurrency for men with and without pregnant or postpartum sexual partners. We used monthly retrospective panel data from Ghana from three perspectives: couple-level data, female reports of pregnancy and male partner concurrency, and male reports of concurrent partnerships and female partner pregnancy. Coital frequency increased during the first trimester and then declined with advancing pregnancy. However, in all three analyses, there was no compelling evidence that men with pregnant or postpartum partners had additional concurrent partnerships. Our findings suggest that even though women's sexual activity likely declines during pregnancy and postpartum, they may not be at increased risk of HIV/STI due to their partners seeking additional partnerships.

A sexually transmitted infection model with long-term partnerships in homogeneous and heterogenous populations

Population models for sexually transmitted infections frequently use a transmission model that assumes an inherent partnership length of zero. However, in a population with long-term partnerships, the infection status of the partners, the length of the partnership, and the exclusivity of the partnership significantly affect the rate of infection. We develop an autonomous population model that can account for the possibilities of an infection from either a casual sexual partner or a longtime partner who was either infected at the start of the partnership or was newly infected. The impact of the long-term partnerships on the rate of infection is captured by calculating the expected values of the rate of infection from these extended contacts. We present a new method to evaluate partner acquisition rates for casual or long-term partnerships which produces in a more realistic number of lifetime sexual partners. Results include a SI model with different infectiousness levels for the transmission of HIV and HSV-2 with acute and chronic/latent infection stages for homogeneous (MSM) and heterogeneous (WSM-MSW) groups. The accompanying reproduction number and sensitivity studies highlight the impact of both casual and long-term partnerships on infection spread. We construct an autonomous set of equations that handle issues usually ignored by autonomous equations and handled only through simulations or in a non-autonomous form. The autonomous formulation of the model allows for simple numerical computations while incorporating a combination of random instantaneous contacts between individuals and prolonged contacts between specific individuals.

Sexual Behavior With Noncommercial Partners: A Concurrent Partnership Study Among Middle-Aged Female Sex Workers in China

Female sex workers (FSWs) often engage in concurrent partnerships, meaning they have multiple sexual relationships at the same time. The objective of this study was to investigate sexual concurrency and its associations with condom use and syphilitic infections among FSWs over age 35. Respondent-driven sampling was used to recruit 1,245 FSWs in Nanning, Hefei, and Qingdao, China. FSWs were asked to report whether they had concurrent partners in the past six months. Concurrency was defined as engagement in sex with commercial clients and (1) husbands and boyfriends (n = 167); (2) husbands only (n = 301); or (3) boyfriends only (n = 469). FSWs with only commercial clients were used as the comparison group (n = 308). Across all groups, the percentage of FSWs with prevalent and active syphilis ranged from 19.6% to 25.6% and 9.1% to 11.5%, respectively. Condom use was low with noncommercial sexual partners and was more likely to be used when FSWs' boyfriends had other partners. Three components of the theory of planned behavior were significantly associated with consistent condom use. Concurrent relationships may lead to increased transmission of syphilis at the workplace and family levels. Effective interventions should target concurrency with both commercial and noncommercial partners.

Association between substance use and concurrent sexual relationships among urban slum dwellers in Nairobi, Kenya

While the overall incidence and prevalence of HIV/AIDS are declining in Africa, substance use-related HIV/AIDS is on the rise. The main objectives of this study were to elicit the types of commonly used substances and to examine the association between substance use and concurrent sexual relationships among slum dwellers in Kenya. Freelisting elicitation techniques were used to identify the most commonly used substances using 53 key informants. This was followed by a self-administered, structured questionnaire using a convenience sample of 506 participants. Findings from our freelisting analysis produced 27 substances that were used in the community. Analysis of the survey data shows that participants who reported using substances in the past three months were more likely to be involved in concurrent sexual relationships than those who did not (86.2% vs. 74.0%; p = .002). In the multivariable model, the odds of ever having concurrent sexual relationships were higher among participants who used any substance in the past three months (aOR 2.46; 95% CI 1.37-4.42, p < .01). The observed association between substance use and concurrent sexual relationships may be influenced by social and economic factors such as poverty and lack of opportunity among urban slum dwellers.

Concurrence and selection of sexual partners as predictors of condom use among Mexican indigenous migrant workers

OBJECTIVE

To identify if the selection of mixed sexual partners and the existence of concurrent partners are predictors of condom use in indigenous migrant agricultural workers from Colima, Mexico.

METHODS

Analytical cross-sectional study using an egocentric sexual network approach. Community interviewers applied a structured questionnaire to 192 indigenous migrant workers in a sugarcane agro-industrial context. Data were analyzed with binary logistic regression; odds ratios (OR) and 95% confidence intervals (CI 95%) were estimated.

RESULTS

In the logistic regression model, adjusted odds (OR; 95% CI) of steady condom use were lower within partnerships of the same indigenous ethnicity compared to other partnerships (0.30; 0.17-0.53), partnerships that were concurrent to other partnerships (0.27; 0.15-0.50), and partnerships that used illegal drugs during sex to other partnerships (0.23; 0.11-0.49). Those variables were actually associated with increased risk of unprotected sex (occasionally or never using condoms), and therefore exposures were unprotected.

CONCLUSION

Sexual partners of the same ethnicity, concurrent partnerships and partnerships that use illegal drugs favor the low frequency of constant condom use and, in turn, the vulnerability to STIs and HIV transmission in indigenous migrant agricultural workers.

Mental Representation of Self in Relationships Indirectly Affects Young Black Women's Engagement in Risky Sexual Behaviors Through Psychosocial HIV/STI Risk Factors

Black females are disproportionately affected by HIV/STIs, though individual-level sexual risk factors do not appear to explain racial/ethnic HIV incidence rate disparities. The current study examined the roles of attachment representations, working models of self and others, with psychosocial risk factors related to population-level sexual network features in association with risky sexual behaviors. A total of 560 Black emerging adult females (M age= 20.58, SD = 1.89) enrolling in a behavioral HIV prevention intervention trial completed the baseline assessment used in the current analyses. A series of multiple mediator models examined indirect effects of working models of self and others on sexual risk engagement through the following psychosocial HIV/STI risk factor: (a) partner communication self-efficacy, (b) fear of condom negotiation, (c) peer norms for risky sexual behavior, (d) partner trust, and (e) sex-related alcohol expectancies. Results indicated indirect effects of working model of self on: condom use with boyfriend/main partner through peer norms for risky sex (ab = .08 ,95% CI [.02, .17]); any alcohol use prior to sex through peer norms for risky sex (ab = -.06, 95% CI [-.12, -.02]); and alcohol use prior to sex through sex-related alcohol expectancies (ab = -.13, 95% CI [-.21, -.05]). Findings indicated direct associations between working model of self and all the psychosocial HIV/STI risk factors included in the mediation models. Working model of self may help identify Black females elevated risk for HIV/STI through these psychosocial risk factors.

HIV prevalence correlated with circumcision prevalence and high-risk sexual behavior in India's states: an ecological study

Background: HIV prevalence varies between 0% and 1.6% in India's states. The factors underpinning this variation are poorly defined.

Methods: We evaluated the relationship between HIV prevalence by state and a range of risk factors in the Indian 2015 National Family Health Survey. Pearson’s correlation was used to assess the relationship between HIV prevalence and each variable. The prevalence of each risk factor was compared between five high-HIV-prevalence states (>1% prevalence) and a large low-HIV-prevalence state (Uttar Pradesh; HIV prevalence, 0.06%).

Results: There was an association between HIV prevalence and men's mean lifetime number of partners (r = 0.55; P = 0.001) and men reporting sex with a non-married, non-cohabiting partner (r = 0.40; P = 0.014). In general, men in high-prevalence states were less likely to be circumcised and (with the exception of Chandigarh) use condoms at last sex. In two high prevalence states (Mizoram and Nagaland), men reported a higher number of lifetime partners and a higher prevalence of multiple partners and high-risk sex in the past year.

Conclusions: Variation in circumcision prevalence and sexual behavior may contribute to the large variations in HIV prevalence by state in India.

Differential sexual network connectivity offers a parsimonious explanation for population-level variations in the prevalence of bacterial vaginosis: a data-driven, model-supported hypothesis

BACKGROUND

The prevalence of bacterial vaginosis (BV) and vaginal microbiota types varies dramatically between different populations around the world. Understanding what underpins these differences is important, as high-diversity microbiotas associated with BV are implicated in adverse pregnancy outcomes and enhanced susceptibility to and transmission of sexually transmitted infections.

MAIN TEXT

We hypothesize that these variations in the vaginal microbiota can, in part, be explained by variations in the connectivity of sexual networks. We argue: 1) Couple-level data suggest that BV-associated bacteria can be sexually transmitted and hence high sexual network connectivity would be expected to promote the spread of BV-associated bacteria. Epidemiological studies have found positive associations between indicators of network connectivity and the prevalence of BV; 2) The relationship between BV prevalence and STI incidence/prevalence can be parsimoniously explained by differential network connectivity; 3) Studies from other mammals are generally supportive of the association between network connectivity and high-diversity vaginal microbiota.

CONCLUSION

To test this hypothesis, we propose a combination of empirical and simulation-based study designs.

Trends in Geographic Rates of HIV Diagnoses Among Black Females in the United States, 2010-2015

BACKGROUND

HIV diagnoses among females in the United States declined 22% from 2010 to 2015, including a 27% decline in diagnoses among black females. Despite this progress, disparities persist. Black females accounted for 60% of new HIV diagnoses among females in 2015. Geographic disparities also exist. This article describes geographic differences in HIV diagnoses among black females in the United States, from 2010 to 2015.

MATERIALS AND METHODS

We examined HIV surveillance data from 2010 to 2015 to determine in which geographic areas decreases or increases in HIV diagnoses occurred. We used data from the National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention's (NCHHSTP) AtlasPlus to calculate percent changes in HIV diagnosis rates by geographic region for black females ≥13 years of age.

RESULTS

The number of new HIV diagnoses declined 27% among black females from 2010 to 2015. The highest rates of HIV diagnosis per 100,000 population of black females, from 2010 to 2015, were in the Northeast and the South. In 2015, five of the eight states reporting the highest rates of HIV diagnosis (i.e., the highest quartile) were in the South.

CONCLUSIONS

HIV diagnosis rates decreased nationally among black females, but the decreases were not uniform within regions or across the United States. Some states experienced increases, and black females in the South and Northeast remain disproportionately affected. Additional research is needed to ascertain factors associated with the increases to continue progress toward reducing HIV-related disparities among females in the United States.

Differences in Chlamydia trachomatis seroprevalence between ethnic groups cannot be fully explained by socioeconomic status, sexual healthcare seeking behavior or sexual risk behavior: a cross-sectional analysis in the HEalthy LIfe in an Urban Setting (HELIUS) study

Background

In the Netherlands, there are strong disparities in Chlamydia trachomatis (CT) prevalence between ethnic groups. The current study aims to identify whether socioeconomic status, sexual risk behavior and sexual healthcare seeking behavior may explain differences in CT seroprevalence between ethnic groups.

Methods

We used 2011–2014 baseline data of the HELIUS (HEalthy LIfe in an Urban Setting) study, a multi-ethnic population-based cohort study in Amsterdam, the Netherlands, including participants from Dutch, African Surinamese, South-Asian Surinamese, Ghanaian, Moroccan and Turkish origin. For this analysis, we selected sexually active, heterosexual participants aged 18–34 years old. CT seroprevalence was determined using a multiplex serology assay. The CT seroprevalence ratios between different ethnicities are calculated and adjusted for potential indicators of socioeconomic status, sexual risk behavior and sexual healthcare seeking behavior.

Results

The study population consisted of 2001 individuals (52.8% female) with a median age of 28 years (IQR 24–31). CT seropositivity differed by ethnicities and ranged from 71.6% (African Surinamese), and 67.9% (Ghanaian) to 31.1% (Turkish). The CT seroprevalence ratio of African Surinamese was 1.72 (95% CI 1.43–2.06) and 1.52 (95% CI 1.16–1.99) of Ghanaian as compared to the Dutch reference group, after adjustment for socioeconomic status, sexual risk behavior and sexual healthcare seeking behavior.

Conclusions

Indicators of socioeconomic status, sexual risk behavior, and sexual health seeking behavior could not explain the higher CT seroprevalence among African Surinamese and Ghanaian residents of Amsterdam.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3533-7) contains supplementary material, which is available to authorized users.

It's the network, stupid: a population's sexual network connectivity determines its STI prevalence

There is little consensus as to why sexually transmitted infections (STIs), including HIV and bacterial vaginosis (BV) are more prevalent in some populations than others. Using a broad definition of sexual network connectivity that includes both structural and conductivity-related factors, we argue that the available evidence suggests that high prevalence of traditional STIs, HIV and BV can be parsimoniously explained by these populations having more connected sexual networks. Positive feedback, whereby BV and various STIs enhance the spread of other STIs, then further accentuates the spread of BV, HIV and other STIs. We review evidence that support this hypothesis and end by suggesting study designs that could further evaluate the hypothesis, as well as implications of this hypothesis for the prevention and management of STIs.

Strong association between higher-risk sex and HIV prevalence at the regional level: an ecological study of 27 sub-Saharan African countries

Background: It is unclear why HIV prevalence varies by nearly two orders of magnitude between regions within countries in sub-Saharan Africa. In this ecological study, we assess if HIV prevalence by region is associated with any of four markers of higher risk sexual behavior: lifetime number of partners, multiple partners in past year, higher risk sex (defined as sex with non-cohabiting, non-marital partners) and age at debut. Methods: We performed Pearson's correlation between the 4 behavioral risk factors and HIV prevalence by region in 47 nationally representative surveys from 27 sub-Saharan African countries, separately by gender. In addition, principal components analysis was used to reduce the eight risk factors (four for each gender) to two principal components (PCs). Mixed effects linear regression was used to assess the relationship between the resulting two PCs and HIV prevalence after controlling for the prevalence of male circumcision. Results: HIV prevalence varied by a median 3.7 fold (IQR 2.9-7.9) between regions within countries. HIV prevalence was strongly associated with higher risk sex and, to a lesser extent, the other risk factors evaluated. Both PCs were strongly associated with HIV prevalence when assessed via linear regression. Conclusions: Differences in sexual behavior may underpin the large differences in HIV-prevalence between subpopulation within sub-Saharan African countries.