Behavior Change Among HIV-Negative Men Who Have Sex with Men Not Using PrEP in the United States.

This study measures changes in condomless anal sex (CAS) among HIV-negative men who have sex with men (MSM) who are not taking pre-exposure prophylaxis (PrEP). It considers the 2014-2019 cycles of the American Men's Internet Survey, a serial, cross-sectional web-based survey of US cisgender MSM aged ≥ 15 years, in which ~ 10% of each year's sample is drawn from the previous year. Among those surveyed for 2 years who remained HIV-negative and off PrEP, reports of having any CAS and of CAS partner number were compared across years. We disaggregated by partner HIV status, and considered demographic predictors. The overall population saw a significant 2.2 percentage-point (pp) increase in reports of any CAS year-over-year. Sub-populations with the largest year-on-year increases were 15-24-year-olds (5.0-pp) and Hispanic respondents (5.1-pp), with interaction (young Hispanic respondents = 12.8-pp). On the relative scale, these numbers correspond to 3.2%, 7.2%, 7.3% and 18.7%, respectively. Absolute increases were concentrated among partners reported as HIV-negative. Multivariable analyses for CAS initiation found effects concentrated among Hispanic and White youth and residents of fringe counties of large metropolitan areas. CAS partner number increases were similarly predicted by Hispanic identity and young age. Although condom use remains more common than PrEP use, increasing CAS among MSM not on PrEP suggests potential new HIV transmission pathways. Concentration of increases among 18-24-year-old MSM portends future increases in the proportion of newly diagnosed HIV that occur among youth. Concentration among young Hispanic MSM will likely expand existing disparities. Although reducing barriers to PrEP remains vital, condom promotion for MSM remains a key public health practice and appears to be missing key audiences. LGBTQ+-inclusive sex education is one avenue for enhancing these efforts.

Changes in Oral and Anal Sex With Opposite-Sex Partners Among Sexually Active Females and Males Aged 15 to 44 Years in the United States: National Survey of Family Growth, 2011-2019.

BACKGROUND: Oral and anal sex with opposite-sex partners is common and associated with sexually transmitted infection (STI) transmission. Trends in these behaviors over the last decade, during which bacterial STI diagnoses have reached historic highs while HIV diagnoses have decreased, are not well understood. We examined recent trends in oral and anal sex and associated condom use with opposite-sex partners among females and males. METHODS: We analyzed data from 16,926 female and 13,533 male respondents aged 15 to 44 years who reported sex with an opposite-sex partner in the past 12 months from the National Survey of Family Growth, 2011-2019. We used survey-weighted linear or logistic regression to evaluate linear temporal trends in oral and anal sex behaviors. RESULTS: From 2011-2013 to 2017-2019, reports of oral sex and number of oral sex partners in the past 12 months increased among females (85.4% in 2011-2013 to 89.4% in 2017-2019; odds ratio [OR], 1.05 [95% confidence interval {CI}, 1.02-1.09], and ß = 0.014 [95% CI, 0.005-0.023]; respectively) but not males (ranges, 87.9%-89.1%; 1.27-1.31). Condom use at last oral sex decreased among both females and males (6.3%-4.3%: OR, 0.93 [95% CI, 0.88-0.99]; 5.9%-4.4%: OR, 0.95 [95% CI, 0.91-1.00]). Anal sex (ranges, 21.0%-23.3% [females] and 23.3%-24.6% [males]), number of anal sex partners (females, 0.22-0.25; males, 0.26-0.30), and condom use at last anal sex (females, 15.3%-18.2%; males, 27.0%-28.7%) remained stable. CONCLUSIONS: The frequency of oral and anal sex with opposite-sex partners among U.S. 15- to 44-year-olds, paired with limited and-for oral sex-decreasing condom use, demonstrates the need to understand the role of these behaviors in increasing STI diagnosis rates and the potential role of extragenital screening and condoms in reducing STI transmission.

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.

Achieving the "Ending the HIV Epidemic in the U.S." incidence reduction goals among at-risk populations in the South.

INTRODUCTION: Antiretroviral medication coverage remains sub-optimal in much of the United States, particularly the Sothern region, and Non-Hispanic Black or African American persons (NHB) continue to be disproportionately impacted by the HIV epidemic. The "Ending the HIV Epidemic in the U.S." (EHE) initiative seeks to reduce HIV incidence nationally by focusing resources towards the most highly impacted localities and populations. This study evaluates the impact of hypothetical improvements in ART and PrEP coverage to estimate the levels of coverage needed to achieve EHE goals in the South. METHODS: We developed a stochastic, agent-based network model of 500,000 individuals to simulate the HIV epidemic and hypothetical improvements in ART and PrEP coverage. RESULTS: New infections declined by 78.6% at 90%/40% ART/PrEP and 94.3% at 100%/50% ART/PrEP. Declines in annual incidence rates surpassed 75% by 2025 with 90%/40% ART/PrEP and 90% by 2030 with 100%/50% ART/PrEP coverage. Increased ART coverage among NHB MSM was associated with a linear decline in incidence among all MSM. Declines in incidence among Hispanic/Latino and White/Other MSM were similar regardless of which MSM race group increased their ART coverage, while the benefit to NHB MSM was greatest when their own ART coverage increased. The incidence rate among NHB women declined by over a third when either NHB heterosexual men or NHB MSM increased their ART use respectively. Increased use of PrEP was associated with a decline in incidence for the groups using PrEP. MSM experienced the largest absolute declines in incidence with increasing PrEP coverage, followed by NHB women. CONCLUSIONS: Our analysis indicates that it is possible to reach EHE goals. The largest reductions in HIV incidence can be achieved by increasing ART coverage among MSM and all race groups benefit regardless of differences in ART initiation by race. Improving ART coverage to > 90% should be prioritized with a particular emphasis on reaching NHB MSM. Such a focus will reduce the largest number of incident cases, reduce racial HIV incidence disparities among both MSM and women, and reduce racial health disparities among persons with HIV. NHB women should also be prioritized for PrEP outreach.

Effect of an opt-out point-of-care HIV-1 nucleic acid testing intervention to detect acute and prevalent HIV infection in symptomatic adult outpatients and reduce HIV transmission in Kenya: a randomized controlled trial.

BACKGROUND: In sub-Saharan Africa, adult outpatients with symptoms of acute infectious illness are not routinely tested for prevalent or acute HIV infection (AHI) when seeking healthcare. METHODS: Adult symptomatic outpatients aged 18-39 years were evaluated by a consensus AHI risk score. Patients with a risk score ≥ 2 and no previous HIV diagnosis were enrolled in a stepped-wedge trial of opt-out delivery of point-of-care (POC) HIV-1 nucleic acid testing (NAAT), compared with standard provider-initiated HIV testing using rapid tests in the observation period. The primary outcome was the number of new diagnoses in each study period. Generalized estimating equations with a log-binomial link and robust variance estimates were used to account for clustering by health facility. The trial is registered with ClinicalTrials.gov NCT03508908. RESULTS: Between 2017 and 2020, 13 (0.9%) out of 1374 participants in the observation period and 37 (2.5%) out of 1500 participants in the intervention period were diagnosed with HIV infection. Of the 37 newly diagnosed cases in the intervention period, two (5.4%) had AHI. Participants in the opt-out intervention had a two-fold greater odds of being diagnosed with HIV (odds ratio = 2.2, 95% confidence interval: 1.39-3.51) after adjustment for factors imbalanced across study periods. CONCLUSIONS: Among symptomatic adults aged 18-39 years targeted by our POC NAAT intervention, we identified one chronic HIV infection for every 40 patients and one AHI patient for every 750 patients tested. Although AHI yield was low in this population, routinely offered opt-out testing could diagnose twice as many patients as an approach relying on provider discretion.

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.

Impacts of Changing Sexual Behavior on Chlamydia and Gonorrhea Burden Among US High School Students, 2007 to 2017.

BACKGROUND: Rates of adolescent sexual activity have long been declining in the United States. We sought to estimate the number of cases of gonorrhea and chlamydia averted over 1 decade associated with these declines and associated costs saved. METHODS: We analyzed data from the Centers for Disease Control and Prevention's Youth Risk Behavior Survey of US high school students from 2007 to 2017 and combined it with epidemiological estimates drawn from the literature to parameterize a dynamic population transmission model. We compared transmissions from observed behavioral trends with a counterfactual scenario that assumed sexual behaviors from 2007 remained constant for 10 years. We calculated outcomes by age and for 3 racial/ethnic groups (Hispanic, non-Hispanic Black, and non-Hispanic White adolescents) who vary on underlying burden and amount of behavioral change. RESULTS: We estimated 1,118,483 cases of chlamydia and 214,762 cases of gonorrhea were averted (19.5% of burden across all ages). This yielded $474 million (2017 dollars) savings in medical costs over the decade. The largest number of averted cases (767,543) was among Black adolescents, but the largest proportion (28.7%) was among Hispanic adolescents. CONCLUSIONS: Whatever its origins, changing sexual behavior among adolescents results in large estimated reductions in STI burden and medical costs relative to previous cohorts. Although diagnoses among adolescents have not declined at this rate, multiple explanations could make these apparently divergent trends consistent. Efforts to continue supporting effective sex education in and out of school along with STI screening for adolescents should reinforce these gains.

Effects of Condom Use on Human Immunodeficiency Virus Transmission Among Adolescent Sexual Minority Males in the United States: A Mixed Epidemiology and Epidemic Modeling Study.

BACKGROUND: We examined condom use patterns and potential population-level effects of a hypothetical condom intervention on human immunodeficiency virus (HIV) transmission among adolescent sexual minority males (ASMM). METHODS: Using 3 data sets: national Youth Risk Behavior Survey 2015 to 2017 (YRBS-National), local YRBS data from 8 jurisdictions with sex of partner questions from 2011 to 2017 (YRBS-Trends), and American Men's Internet Survey (AMIS) 2014 to 2017, we assessed associations of condom use with year, age, and race/ethnicity among sexually active ASMM. Using a stochastic agent-based network epidemic model, structured and parameterized based on the above analyses, we calculated the percent of HIV infections averted over 10 years among ASMM ages 13 to 18 years by an intervention that increased condom use by 37% for 5 years and was delivered to 62% of ASMM at age 14 years. RESULTS: In YRBS, 51.8% (95% confidence interval [CI], 41.3-62.3%) and 37.9% (95% CI, 32.7-42.3%) reported condom use at last sexual intercourse in national and trend data sets, respectively. In AMIS, 47.3% (95% CI, 44.6-49.9%) reported condom use at last anal sex with a male partner. Temporal trends were not observed in any data set (P > 0.1). Condom use varied significantly by age in YRBS-National (P < 0.0001) and YRBS-Trends (P = 0.032) with 13- to 15-year-olds reporting the lowest use in both; age differences were not significant in AMIS (P = 0.919). Our hypothetical intervention averted a mean of 9.0% (95% simulation interval, -5.4% to 21.2%) of infections among ASMM. CONCLUSIONS: Condom use among ASMM is low and appears to have remained stable during 2011 to 2017. Modeling suggests that condom use increases, consistent with previous interventions, have potential to avert 1 in 11 new HIV infections among ASMM.

A Behavioral Cascade of HIV Seroadaptation Among US Men Who Have Sex with Men in the Era of PrEP and U = U.

Seroadaptive behaviors help reduce HIV risk for some men who have sex with men (MSM), and have been well documented across MSM populations. Advancements in biomedical prevention have changed the contexts in which seroadaptive behaviors occur. We thus sought to estimate and compare the prevalence of four stages of the "seroadaptive cascade" by PrEP use in the recent era: knowledge of own serostatus, knowledge of partner serostatus; serosorting (matching by status), and condomless anal intercourse. Serosorting overall appeared to remain common, especially with casual and one-time partners. Although PrEP use did not impact status discussion, it did impact serosorting and the likelihood of having condomless anal intercourse. For respondents not diagnosed with HIV and not on PrEP, condomless anal intercourse occurred in just over half of relationships with HIV-positive partners who were not on treatment. Biomedical prevention has intertwined with rather than supplanted seroadaptive behaviors, while contexts involving neither persist.

RESUMEN: Los comportamientos seroadaptivos ayudan a reducir el riesgo de VIH en algunos hombres que tienen sexo con otros hombres (HSH) y han sido bien documentados en varias comunidades de HSH. Los avances en prevención biomédica han cambiado los contextos de los comportamientos seroadaptivos. Por ello buscamos estimar y comparar la prevalencia de cuatro fases de la 'cascada seroadaptiva' mediante el uso de PrEP en la era reciente: conocimiento del seroestatus personal, conocimiento del seroestatus del compañero, serosorting (emparejamiento por estatus) y coito anal sin condón. En general, el serosorting parece seguir siendo común especialmente con parejas casuales o de una noche. A pesar de que el uso de PrEP no impactó la discusión sobre el estatus, sí impactó el serosorting y la probabilidad de coito anal sin condón. Los encuestados no diagnosticados con VIH y sin PrEP tuvieron coito anal sin condón en la mitad de las relaciones con parejas VIH-positivo que no estaban bajo tratamiento. La prevención biomédica se ha entremezclado en lugar de suplantar los comportamientos seropositivos, mientras persisten los contextos en los que no aparece ninguno.

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.

Does Stigma Toward Anal Sexuality Impede HIV Prevention Among Men Who Have Sex With Men in the United States? A Structural Equation Modeling Assessment.

INTRODUCTION: Men who have sex with men (MSM) are suboptimally engaged in efficacious HIV interventions, due in part to stigma. AIM: We sought to validate the Anal Health Stigma Model, developed based on theory and prior qualitative data, by testing the magnitude of associations between measures of anal sex stigma and engagement in HIV prevention practices, while adjusting for covariates. METHODS: We conducted a cross-sectional online survey of 1,263 cisgender MSM living in the United States and analyzed data with structural equation modeling. We tested a direct path from Anal Sex Stigma to Engagement in HIV Prevention alongside 2 indirect paths, 1 through Anal Sex Concerns and another through Comfort Discussing Anal Sexuality with Health Workers. The model adjusted for Social Support, Everyday Discrimination, and Sociodemographics. MAIN OUTCOME MEASURE: Engagement in HIV Prevention comprised an ad hoc measure of (i) lifetime exposure to a behavioral intervention, (ii) current adherence to biomedical intervention, and (iii) consistent use of a prevention strategy during recent penile-anal intercourse. RESULTS: In the final model, anal sex stigma was associated with less engagement (ß = -0.22, P < .001), mediated by participants' comfort talking about anal sex practices with health workers (ß = -0.52; ß = 0.44; both P < .001), adjusting for covariates (R2 = 67%; χ2/df = 2.98, root mean square error of approximation = 0.040, comparative fit index = 0.99 and Tucker-Lewis index = 0.99). Sex-related concerns partially mediated the association between stigma and comfort (ß = 0.55; ß = 0.14, both P < .001). Modification indices also supported total effects of social support on increased comfort discussing anal sex (ß = 0.35, P < .001) and, to a lesser degree, on decreased sex-related concerns (ß = -0.10; P < .001). CLINICAL IMPLICATIONS: Higher stigma toward anal sexuality is associated with less engagement in HIV prevention, largely due to discomfort discussing anal sex practices with health workers. STRENGTH & LIMITATIONS: Adjustment for mediation in a cross-sectional design cannot establish temporal causality. Self-report is vulnerable to social desirability and recall bias. Online samples may not represent cisgender MSM in general. However, findings place HIV- and health-related behaviors within a social and relational context and may suggest points for intervention in health-care settings. CONCLUSION: Providers' willingness to engage in discussion about anal sexuality, for example, by responding to questions related to sexual well-being, may function as social support and thereby bolster comfort and improve engagement in HIV prevention. Kutner BA, Simoni JM, King KM, et al. Does Stigma Toward Anal Sexuality Impede HIV Prevention Among Men Who Have Sex With Men in the United States? A Structural Equation Modeling Assessment. J Sex Med 2020;17:477-490.

Large benefits to youth-focused HIV treatment-as-prevention efforts in generalized heterosexual populations: An agent-based simulation model.

Predominantly heterosexual HIV-1 epidemics like those in sub-Saharan Africa continue to have high HIV incidence in young people. We used a stochastic, agent-based model for age-disparate networks to test the hypothesis that focusing uptake and retention of ART among youth could enhance the efficiency of treatment as prevention (TasP) campaigns. We used the model to identify strategies that reduce incidence to negligible levels (i.e., < 0.1 cases/100 person-years) 20-25 years after initiation of a targeted TasP campaign. The model was parameterized using behavioral, demographic, and clinical data from published papers and national reports. To keep a focus on the underlying age effects we model a generalized heterosexual population with average risks (i.e., no MSM, no PWIDs, no sex workers) and no entry of HIV+ people from other regions. The model assumes that most people (default 95%, range in variant simulations 60-95%) are "linkable"; i.e., could get linked to effective care given sufficient resources. To simplify the accounting, we assume a rapid jump in the number of people receiving treatment at the start of the TasP campaign, followed by a 2% annual increase that continues until all linkable HIV+ people have been treated. Under historical scenarios of CD4-based targeted ART allocation and current policies of untargeted (random) ART allocation, our model predicts that viral replication would need to be suppressed in 60-85% of infected people at the start of the TasP campaign to drive incidence to negligible levels. Under age-based strategies, by contrast, this percentage dropped by 18-54%, depending on the strength of the epidemic and the age target. For our baseline model, targeting those under age 30 halved the number of people who need to be treated. Age-based targeting also minimized total and time-discounted AIDS deaths over 25 years. Age-based targeting yielded benefits without being highly exclusive; in a model in which 60% of infected people were treated, ~87% and ~58% of those initiating therapy during a campaign targeting those <25 and <30 years, respectively, fell outside the target group. Sensitivity analyses revealed that youth-focused TasP is beneficial due to age-related risk factors (e.g. shorter relationship durations), and an age-specific herd immunity (ASHI) effect that protects uninfected adolescents entering the sexually active population. As testing rates increase in response to UNAIDS 90-90-90 goals, efforts to link all young people to care and treatment could contribute enormously to ending the HIV epidemic.

Addressing Gaps in HIV Preexposure Prophylaxis Care to Reduce Racial Disparities in HIV Incidence in the United States.

The potential for human immunodeficiency virus (HIV) preexposure prophylaxis (PrEP) to reduce the racial disparities in HIV incidence in the United States might be limited by racial gaps in PrEP care. We used a network-based mathematical model of HIV transmission for younger black and white men who have sex with men (BMSM and WMSM) in the Atlanta, Georgia, area to evaluate how race-stratified transitions through the PrEP care continuum from initiation to adherence and retention could affect HIV incidence overall and disparities in incidence between races, using current empirical estimates of BMSM continuum parameters. Relative to a no-PrEP scenario, implementing PrEP according to observed BMSM parameters was projected to yield a 23% decline in HIV incidence (hazard ratio = 0.77) among BMSM at year 10. The racial disparity in incidence in this observed scenario was 4.95 per 100 person-years at risk (PYAR), a 19% decline from the 6.08 per 100 PYAR disparity in the no-PrEP scenario. If BMSM parameters were increased to WMSM values, incidence would decline by 47% (hazard ratio = 0.53), with an associated disparity of 3.30 per 100 PYAR (a 46% decline in the disparity). PrEP could simultaneously lower HIV incidence overall and reduce racial disparities despite current gaps in PrEP care. Interventions addressing these gaps will be needed to substantially decrease disparities.

Monitoring HIV Preexposure Prophylaxis Use Among Men Who Have Sex With Men in Washington State: Findings From an Internet-Based Survey.

BACKGROUND: Many state and local health departments now promote and support the use of HIV preexposure prophylaxis (PrEP), yet monitoring use of the intervention at the population level remains challenging. METHODS: We report the results of an online survey designed to measure PrEP use among men who have sex with men (MSM) in Washington State. Data on the proportion of men with indications for PrEP based on state guidelines and levels of awareness, interest, and use of PrEP are presented for 1080 cisgender male respondents who completed the survey between January 1 and February 28, 2017. We conducted bivariate and multivariable logistic regression to identify factors associated with current PrEP use. To examine patterns of discontinuation, we conducted Cox proportional hazards regression and fit a Kaplan-Meier curve to reported data on time on PrEP. RESULTS: Eighty percent of respondents had heard of PrEP, 19% reported current use, and 36% of men who had never used PrEP wanted to start taking it. Among MSM for whom state guidelines recommend PrEP, 31% were taking it. In multivariable analysis, current PrEP use was associated with older age, higher education, and meeting indications for PrEP use. Our data suggest that 20% of PrEP users discontinue within 12 months, and men with lower educational attainment were more likely to discontinue. CONCLUSIONS: Despite high levels of use, there is significant unmet need for PrEP in Washington. Our experience indicates that Internet surveys are feasible and informative for monitoring PrEP use in MSM.

Potential Impact of HIV Preexposure Prophylaxis Among Black and White Adolescent Sexual Minority Males.

OBJECTIVES: To assess the potential impact of preexposure prophylaxis (PrEP) on the HIV epidemic among Black and White adolescent sexual minority males (ASMM). METHODS: We used a network model and race-specific data from recent trials to simulate HIV transmission among a population of Black and White 13- to 18-year-old ASMM over 20 years. We estimated the number of infections prevented (impact) and the number needed to treat to prevent an infection (efficiency) under multiple coverage and adherence scenarios. RESULTS: At modeled coverage and adherence, PrEP could avert 3% to 20% of infections among Black ASMM and 8% to 51% among White ASMM. A larger number, but smaller percentage, of infections were prevented in Black ASMM in all scenarios examined. PrEP was more efficient among Black ASMM (number needed to treat to avert an infection = 25-32) compared with White ASMM (146-237). CONCLUSIONS: PrEP can reduce HIV incidence among both Black and White ASMM but is far more efficient for Black ASMM because of higher incidence. Public Health Implications. Black ASMM communities suffer disproportionate HIV burden; despite imperfect adherence, PrEP programs could prevent HIV efficiently in these communities.

EpiModel: An R Package for Mathematical Modeling of Infectious Disease over Networks.

Package EpiModel provides tools for building, simulating, and analyzing mathematical models for the population dynamics of infectious disease transmission in R. Several classes of models are included, but the unique contribution of this software package is a general stochastic framework for modeling the spread of epidemics on networks. EpiModel integrates recent advances in statistical methods for network analysis (temporal exponential random graph models) that allow the epidemic modeling to be grounded in empirical data on contacts that can spread infection. This article provides an overview of both the modeling tools built into EpiModel, designed to facilitate learning for students new to modeling, and the application programming interface for extending package EpiModel, designed to facilitate the exploration of novel research questions for advanced modelers.

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

Background: Preexposure prophylaxis (PrEP) is highly effective for preventing human immunodeficiency virus (HIV) infection, but risk compensation (RC) in men who have sex with men (MSM) raises concerns about increased sexually transmitted infections (STIs). The Center for Disease Control and Prevention's (CDC's) PrEP guidelines recommend biannual STI screening, which may reduce incidence by treating STIs that would otherwise remain undiagnosed. We investigated these two counteracting phenomena. Methods: With a network-based mathematical model of HIV, Neisseria gonorrhoeae (NG), and Chlamydia trachomatis (CT) transmission dynamics among MSM in the United States, we simulated PrEP uptake following the prescription indications and HIV/STI screening recommendations in the CDC guidelines. Scenarios varied PrEP coverage (the proportion of MSM indicated for PrEP who received it), RC (a reduction in the per-act probability of condom use), and the STI screening interval. Results: In our reference scenario (40% coverage, 40% RC), 42% of NG and 40% of CT infections would be averted over the next decade. A doubling of RC would still result in net STI prevention relative to no PrEP. STIs declined because PrEP-related STI screening resulted in a 17% and 16% absolute increase in the treatment of asymptomatic and rectal STIs, respectively. Screening and timely treatment at quarterly vs biannual intervals would reduce STI incidence an additional 50%. Conclusions: Implementation of the CDC PrEP guidelines while scaling up PrEP coverage could result in a significant decline in STI incidence among MSM. Our study highlights the design of PrEP not only as antiretroviral medication but as combination HIV/STI prevention incorporating STI screening.

Projected demographic composition of the United States population of people living with diagnosed HIV.

The transformation of HIV from a fatal disease to lifelong disease has resulted in an HIV-infected population that is growing and aging, placing new and increasing demands on public programs and health services. We used National HIV Surveillance System and US census data to project the demographic composition of the population of people living with diagnosed HIV (PLWDH) in the United States through 2045. The input parameters for the projections include: (1) census projections, (2) number of people with an existing HIV diagnosis in 2013, (3) number of new HIV diagnoses in 2013, and (4) death rate within the PLWDH population in 2013. Sex-, risk group-, and race-specific projections were estimated through an adapted Leslie Matrix Model for age-structured populations. Projections for 2013-2045 suggest that the number of PLWDH in the U.S. will consistently grow, from 917,294 to 1,232,054, though the annual growth rate will slow from 1.8% to 0.8%. The number of PLWDH aged 55 years and older will increase from 232,113 to 470,221. The number of non-Hispanic (NH) African Americans/Blacks and Hispanics is projected to consistently grow, shifting the racial/ethnic composition of the US PLWDH population from 32 to 23% NH-White, 42 to 38% NH-Black, and 20-32% Hispanic between 2013 and 2045. Given current trends, the composition of the PLWDH population is projected to change considerably. Public health practitioners should anticipate large shifts in the age and racial/ethnic structure of the PLWDH population in the United States.

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

BACKGROUND: Preexposure prophylaxis (PrEP) is effective for preventing human immunodeficiency virus (HIV) infection among men who have sex with men (MSM) within trial settings. Population impact will depend on clinical indications for PrEP initiation, coverage levels, and drug adherence. No modeling studies have estimated the impact of clinical practice guidelines for PrEP issued by the Centers for Disease Control and Prevention (CDC). METHODS: Mathematical models of HIV transmission among MSM were used to estimate the percentage of infections averted (PIA) and the number needed to treat (NNT) under behavioral indications of the CDC's PrEP guidelines. We modeled the contribution of these indications while varying treatment coverage and adherence. RESULTS: At 40% coverage of indicated MSM over the next decade, application of CDC guidelines would avert 1162 infections per 100 000 person-years, 33.0% of expected infections. The predicted NNT for the guidelines would be 25. Increasing coverage and adherence jointly raise the PIA, but reductions to the NNT were associated with better adherence only. CONCLUSIONS: Implementation of CDC PrEP guidelines would result in strong and sustained reductions in HIV incidence among MSM in the United States. The guidelines strike a good balance between epidemiological impact (PIA) and efficiency (NNT) at plausible scale-up levels. Adherence counseling could maximize public health investment in PrEP by decreasing the NNT.