Community Mitigation Strategies, Mobility, and COVID-19 Incidence Across Three Waves in the United States in 2020.

BACKGROUND: Summarizing the impact of community-based mitigation strategies and mobility on COVID-19 infections throughout the pandemic is critical for informing responses and future infectious disease outbreaks. Here, we employed time-series analyses to empirically investigate the relationships between mitigation strategies and mobility on COVID-19 incident cases across US states during the first three waves of infections. METHODS: We linked data on daily COVID-19 incidence by US state from March to December 2020 with the stringency index, a well-known index capturing the strictness of mitigation strategies, and the trip ratio, which measures the ratio of the number of trips taken per day compared with the same day in 2019. We utilized multilevel models to determine the relative impacts of policy stringency and the trip ratio on COVID-19 cumulative incidence and the effective reproduction number. We stratified analyses by three waves of infections. RESULTS: Every five-point increase in the stringency index was associated with 2.89% (95% confidence interval = 1.52, 4.26%) and 5.01% (3.02, 6.95%) reductions in COVID-19 incidence for the first and third waves, respectively. Reducing the number of trips taken by 50% compared with the same time in 2019 was associated with a 16.2% (-0.07, 35.2%) decline in COVID-19 incidence at the state level during the second wave and 19.3% (2.30, 39.0%) during the third wave. CONCLUSIONS: Mitigation strategies and reductions in mobility are associated with marked health gains through the reduction of COVID-19 infections, but we estimate variable impacts depending on policy stringency and levels of adherence.

Expanding Medicaid to Reduce Human Immunodeficiency Virus Transmission in Houston, Texas: Insights From a Modeling Study.

CONTEXT: Medicaid expansion has been nationally shown to improve engagement in the human immunodeficiency virus (HIV) treatment and prevention continua, which are vital steps to stopping the HIV epidemic. New HIV infections in the United States are disproportionately concentrated among young Black men who have sex with men (YBMSM). Houston, TX, is the most populous city in the Southern United States with a racially/ethnically diverse population that is located in 1 of 11 US states that have not yet expanded Medicaid coverage as of 2021. METHODS: An agent-based model that incorporated the sexual networks of YBMSM was used to simulate improved antiretroviral treatment and pre-exposure prophylaxis (PrEP) engagement through Medicaid expansion in Houston, TX. Analyses considered the HIV incidence (number of new infections and as a rate metric) among YBMSM over the next 10 years under Medicaid expansion as the primary outcome. Additional scenarios, involving viral suppression and PrEP uptake above the projected levels achieved under Medicaid expansion, were also simulated. RESULTS: The baseline model projected an HIV incidence rate of 4.96 per 100 person years (py) and about 368 new annual HIV infections in the 10th year. Improved HIV treatment and prevention continua engagement under Medicaid expansion resulted in a 14.9% decline in the number of annual new HIV infections in the 10th year. Increasing viral suppression by an additional 15% and PrEP uptake by 30% resulted in a 44.0% decline in new HIV infections in the 10th year, and a 27.1% decline in cumulative infections across the 10 years of the simulated intervention. FINDINGS: Simulation results indicate that Medicaid expansion has the potential to reduce HIV incidence among YBMSM in Houston. Achieving HIV elimination objectives, however, might require additional effective measures to increase antiretroviral treatment and PrEP uptake beyond the projected improvements under expanded Medicaid.

The Integration of Value Assessment and Social Network Methods for Breast Health Navigation Among African Americans.

OBJECTIVES: A major strategy to reduce the impact of breast cancer (BC) among African Americans (AA) is patient navigation, defined here as individualized assistance for reducing barriers to healthcare use. The primary focus of this study was to estimate the added value of incorporating breast health promotion by navigated participants and the subsequent BC screenings that network members may obtain. METHODS: In this study, we compared the cost-effectiveness of navigation across 2 scenarios. First, we examine the effect of navigation on AA participants (scenario 1). Second, we examine the effect of navigation on AA participants and their networks (scenario 2). We leverage data from multiple studies in South Chicago. Our primary outcome (BC screening) is intermediate, given limited available quantitative data on the long-term benefits of BC screening for AA populations. RESULTS: When considering participant effects alone (scenario 1), the incremental cost-effectiveness ratio was $3845 per additional screening mammogram. When including participant and network effects (scenario 2), the incremental cost-effectiveness ratio was $1098 per additional screening mammogram. CONCLUSION: Our findings suggest that inclusion of network effects can contribute to a more precise, comprehensive assessment of interventions for underserved communities.

Factors associated with HIV testing and treatment among young Black MSM and trans women in three jail systems.

Black men who have sex with men (BMSM) and transgender women (BTW) are disproportionately affected by incarceration and HIV. We assessed factors associated with HIV testing and viral suppression among 176 incarcerated BMSM and BTW in Chicago, IL; Los Angeles, CA; and Houston, TX. In multivariable logistic regression, having a sexual orientation of bisexual, heterosexual, or other vs. gay or same-gender loving was associated with higher odds of testing in custody (aOR 8.97; 95% CI 1.95 - 41.24). Binge drinking (aOR 0.19; 95% CI 0.04 - 0.92) and being unemployed prior to incarceration (aOR 0.03; 95% CI 0.00 - 0.23) were associated with lower odds of testing; participants in Los Angeles were also more likely to be tested than those in Chicago. Being housed in protective custody (aOR 3.12; 95% CI 1.09-9.59) and having a prescription for ART prior to incarceration (aOR 2.58; 95% CI 1.01-6.73) were associated with higher odds of viral suppression when adjusted for site and duration of incarceration, though the associations were not statistically significant in the full multivariable model. Future research should examine structural and process level factors that impact engagement in HIV testing and treatment among detained BMSM and BTW.

Healthcare Predictors of Information Dissemination About Genetic Risks.

OBJECTIVES: Despite the benefits of genetic counseling and testing (GCT), utilization is particularly low among African American (AA) women who exhibit breast cancer features that are common in BRCA-associated cancer. Underutilization is especially problematic for AA women who are more likely to die from breast cancer than women from any other race or ethnicity. Due to medical mistrust, fear, and stigma that can be associated with genetic services among racial/ethnic minorities, reliance on trusted social networks may be an impactful strategy to increase dissemination of knowledge about hereditary cancer risk. Informed by the social cognitive theory, the purpose of this study is to determine: 1) which AA patients diagnosed with breast cancer and with identified hereditary risk are sharing information about hereditary risk with their networks; 2) the nature of the information dissemination; and 3) if personal GCT experiences is associated with dissemination of information about hereditary risk. METHODS: Among consented participants (n = 100) that completed an interview administered using a 202-item questionnaire consisting of open- and closed-ended questions, 62 patients were identified to be at higher risk for breast cancer. Descriptive statistics, bivariable chi-square, Pearson's exact tests, and regression analyses were conducted to examine differences in characteristics between high-risk participants who disseminated hereditary risk information and participants who did not. RESULTS: Among high-risk participants, 25 (40%) indicated they had disseminated information about hereditary risk to at least one member in their family/friend network and 37 (60%) had not. Receipt of both provider recommendations and receipt of GCT services was associated with greater odds of disseminating information about hereditary risk with networks, OR = 4.53, 95%CI [1.33, 15.50], p = .02. CONCLUSION: Interventions that increase self-efficacy gained through additional personalized knowledge and experience gained through provider recommendations and by undergoing GCT may facilitate information dissemination among social/familial networks.

Patient Navigation Can Improve Breast Cancer Outcomes among African American Women in Chicago: Insights from a Modeling Study.

African American (AA) women experience much greater mortality due to breast cancer (BC) than non-Latino Whites (NLW). Clinical patient navigation is an evidence-based strategy used by healthcare institutions to improve AA women's breast cancer outcomes. While empirical research has demonstrated the potential effect of navigation interventions for individuals, the population-level impact of navigation on screening, diagnostic completion, and stage at diagnosis has not been assessed. An agent-based model (ABM), representing 50-74-year-old AA women and parameterized with locally sourced data from Chicago, is developed to simulate screening mammography, diagnostic resolution, and stage at diagnosis of cancer. The ABM simulated three counterfactual scenarios: (1) a control setting without any navigation that represents the "standard of care"; (2) a clinical navigation scenario, where agents receive navigation from hospital-affiliated staff; and (3) a setting with network navigation, where agents receive clinical navigation and/or social network navigation (i.e., receiving support from clinically navigated agents for breast cancer care). In the control setting, the mean population-level screening mammography rate was 46.3% (95% CI: 46.2%, 46.4%), the diagnostic completion rate was 80.2% (95% CI: 79.9%, 80.5%), and the mean early cancer diagnosis rate was 65.9% (95% CI: 65.1%, 66.7%). Simulation results suggest that network navigation may lead up to a 13% increase in screening completion rate, 7.8% increase in diagnostic resolution rate, and a 4.9% increase in early-stage diagnoses at the population-level. Results suggest that systems science methods can be useful in the adoption of clinical and network navigation policies to reduce breast cancer disparities.

Navigated African American breast cancer patients as incidental change agents in their family/friend networks.

BACKGROUND: Patient navigation is an increasingly widespread intervention to address the persistent, severe, and disproportionate breast cancer (BC) burden that African Americans (AA) face. Navigation may have more widespread effects than previously estimated due to patient-driven diffusion of BC information. METHODS: This pilot study examined the network effects of a randomized controlled trial via recruitment of navigated and non-navigated AA BC patients as well as their network members. We estimated study arm differences in patient BC promotion (i.e., number of individuals to whom BC patients promote BC screening) and network BC screening (i.e., % BC screening among network members). RESULTS: Among our sample of 100 AA BC patients, navigated patients promoted BC screening to more individuals than non-navigated patients. BC patients were more likely to promote BC screening to children and individuals with whom they communicated more frequently. Some models further suggested more network BC screening among "navigated" network members relative to "non-navigated" network members. CONCLUSIONS: Navigated AA patients promoted BC screening more widely throughout their networks than non-navigated AA BC patients. There were also suggestive findings regarding increased BC screening among their network members. Our pilot study highlights the potential for social network analysis to improve the precision of intervention effect estimates and to inform future innovations (e.g., integrating navigation and network-based interventions) with multilevel effects on cancer health disparities.

Sex Partner Behavior Variation Related to Network Position of and Residential Proximity to Sex Partners Among Young Black Men Who Have Sex with Men.

This analysis examines how sex behaviors are influenced by a sex partner's network bridging position and the residential proximity between the two. The study sample consisted of 437 young black men who have sex with men (YBMSM) in Chicago and their sex partners (2013-2014). Dyadic analyses that clustered on individuals using generalized estimating equations (n = 1095 relationships) were conducted to assess the associations between different HIV-related sexual behaviors and the network position of and residential proximity to a partner. The odds of group sex was higher with partners who had high network bridging, regardless of how close they lived to one another. The odds of transactional sex was higher with partners who had high network bridging and lived in a different region of the city. Sex behaviors associated with an increased risk of HIV transmission were associated with the network structural position of and residential proximity to partners among YBMSM.

Socio-Structural and Neighborhood Predictors of Incident Criminal Justice Involvement in a Population-Based Cohort of Young Black MSM and Transgender Women.

Black men who have sex with men (MSM) and transgender women are disproportionately affected by criminal justice involvement (CJI) and HIV. This study recruited 618 young Black MSM and transgender women in Chicago, IL, using respondent-driven sampling between 2013 and 2014. Random effects logistic regression evaluated predictors of incident CJI over 18 months of follow-up. Controlling for respondent age, gender and sexual identity, spirituality (aOR 0.56, 95% CI 0.33-0.96), and presence of a mother figure (aOR 0.41, 95% CI 0.19-0.89) were protective against CJI. Economic hardship (financial or residential instability vs. neither aOR 2.23, 95% CI 1.10-4.51), two or more past episodes of CJI vs. none (aOR 2.66, 95% CI 1.40-5.66), and substance use (marijuana use vs. none aOR 2.79, 95% CI 1.23-6.34; other drug use vs. none aOR 4.49, 95% CI 1.66-12.16) were associated with CJI during follow-up. Research to identify and leverage resilience factors that can buffer the effects of socioeconomic marginalization may increase the effectiveness of interventions to address the socio-structural factors that increase the risk for CJI among Black MSM and transgender women. Given the intersection of incarceration, HIV and other STIs, and socio-structural stressors, criminal justice settings are important venues for interventions to reduce health inequities in these populations.

The potential of online social networking data for augmenting the study of high-risk personal networks among young men who have sex with men at-risk for HIV.

Capturing dynamics in high-risk personal networks is essential for preventing HIV transmission. Online social networking data offer incentive to augment traditional selfreported approaches for network enumeration. To explore what online networks reveal about dynamics among high-risk associates, we examine the relationship between egocentric confidant and sex networks and personal Facebook friendship networks of a cohort of young Black men who have sex with men. Although overlap exists between self-reported and Facebook associates, the stabilities of each were unrelated. Confidants who were also Facebook friends with a respondent were, however, more likely to be retained. Thus, Facebook networks contain stable confidants.

Prescription Opioid Use in a Population-Based Sample of Young Black Men Who Have Sex with Men: A Longitudinal Cohort Study.

Background: Prescription opioid use (POU) among young adults is increasing. This represents a major public health concern due to the increased risks of opioid use misuse and opioid-related overdose. Limited research has examined the POU among young black men who have sex with men (YBMSM), a diverse group experiencing continued increases in HIV incidence over the past decade. Objective: This study aims to examine the prevalence and both the individual and network characteristics of POU among YBMSM. Methods: Data were from a longitudinal cohort study of 16-29 year old YBMSM (N = 514) between 2013 and 2016 in Chicago. Bivariate and multivariable associations were estimated using general estimating equations (GEE). Results: Approximately 4.2% of YBMSM reported POU in the past 12 months with a cumulative incidence rate of 4.1% over the 18-month follow-up period. YBMSM having criminal justice involvements, experiencing violence, or using any illicit drug other than marijuana in the past 12 months were more likely to report POU in the past 12 months. The presence of a mother figure, however, was associated with a decreased risk of POU in the past 12 months, while engaging in condomless anal sex with their named sexual partners was associated with an increased risk of POU in the past 12 months. Conclusions: This is one of the first studies to describe POU among a population-based sample of YBMSM. The high incidence rate of POU among YBMSM is alarming, and it underscores the need for further analysis on POU among this key population.

Human Immunodeficiency Virus Partner Notification Services Among a Representative Sample of Young Black Men Who Have Sex With Men Demonstrates Limited Service Offering and Potential Benefits of Clinic Involvement.

BACKGROUND: Partner notification (PN) is commonly offered to persons recently diagnosed with human immunodeficiency virus (HIV) to improve linkage to care and prevent onward transmission. Yet, much remains unknown about the factors associated with successful PN participation in populations at highest risk. METHODS: Data were collected during the first 2 waves (2013-2015) of "uConnect," a population-based cohort study of young black men who have sex with men in Chicago (N = 618). Participants completed a biobehavioral survey and were tested for HIV. Among HIV-infected participants (N = 187), weighted logistic regression models examined the relationship between participant characteristics and being offered PN and providing partner names. RESULTS: 30.3% (n = 187) of the sample was HIV-positive, of which 71.7% (n = 134) were offered PN, including: 8.2% (n = 11) by the city health department; 51.5% (n = 69) by health care providers; and 40.3% (n = 54) by both. Being offered PN was significantly associated with criminal justice involvement history (adjusted odds ratio [aOR], 2.49; 95% confidence interval [CI], 1.38-4.49), volatile nitrates usage (aOR, 2.88; 95% CI, 1.20-6.94), and recent conversations with HIV outreach workers (aOR, 2.68; 95% CI, 1.25-5.77). Providing partner names was significantly associated with intermittent (aOR, 7.26; 95% CI, 1.75-30.07) and heavy (aOR, 11.47; 95% CI, 2.57-51.22) marijuana use, and being offered PN by both the city health department and health care provider (aOR, 8.36; 95% CI, 2.73-25.62). CONCLUSIONS: A substantial proportion of HIV-diagnosed individuals were never offered PN. Being offered PN by multiple sources is associated with participation, and improved collaboration within health systems may improve participation rates.

PrEP Chicago: A randomized controlled peer change agent intervention to promote the adoption of pre-exposure prophylaxis for HIV prevention among young Black men who have sex with men.

BACKGROUND/AIMS: Advances in biomedical prevention strategies such as pre-exposure prophylaxis (PrEP) represent a new opportunity for reducing HIV incidence among young Black men who have sex with men, for whom the number of new HIV infections continues to rise. However, studies have documented low rates of PrEP uptake in this community. Research suggests that the peer networks of young Black men who have sex with men play important roles in their sexual health decisions. PrEP Chicago is a randomized controlled trial network intervention designed to increase PrEP uptake among young Black men who have sex with men living in Chicago. The aims of this study are twofold. Aim 1 is to estimate the effectiveness of a peer change agent intervention for (1) increasing the number of referrals made to a PrEP information line, (2) increasing the rate of PrEP adoption among non-participant peers, and (3) increasing PrEP knowledge, attitudes, and intentions among participants. Aim 2 is to determine the individual and network variables that explain peer change agent effectiveness. METHODS: PrEP Chicago is a social network intervention that utilizes the influence of peer change agents to link young Black men who have sex with men in Chicago to PrEP. Young Black men who have sex with men were recruited using respondent-driven sampling. Once screened for eligibility, participants were randomly assigned to either one of two treatment sequences: (1) intervention treatment in Year 1 followed by a minimal contact attention control in Year 2 or (2) the minimal contact attention control in Year 1 followed by treatment in Year 2. The treatment consists of a PrEP/peer change agent training workshop followed by booster calls for 12 months. The attention control consists of a sex diary activity designed to help participants assess sexual risk. Psychosocial, sexual health, and network data are collected from all participants at baseline and at 12- and 24-month follow-ups. RESULTS: In total, 423 participants aged 18-35 have been enrolled (more than 100% target enrollment) and have completed baseline data collection. A majority of participants in both intervention and control groups reported having heard of PrEP before enrolling in the study, yet also reported having had no current or prior experience taking PrEP. Statistical analyses await completion of Year 1 of the trial in March 2018. CONCLUSION: PrEP Chicago addresses a gap in HIV prevention research and intervention design by utilizing the existing social networks among young Black men who have sex with men as mechanisms for information diffusion, behavioral influence, social support, and empowerment. Therefore, interventions that leverage peer influence processes to facilitate PrEP uptake are promising strategies to improve sexual health engagement and overcome disparities in outcomes among this at-risk population.

Sex Behaviors as Social Cues Motivating Social Venue Patronage Among Young Black Men Who Have Sex with Men.

HIV prevention programs often focus on the physical social venues where men who have sex with men (MSM) frequent as sites where sex behaviors are assumed to be practiced and risk is conferred. But, how exactly these behaviors influence venue patronage is not well understood. In this study, we present a two-mode network analysis that determines the extent that three types of sex behaviors-condomless sex, sex-drug use, and group sex-influence the patronage of different types of social venues among a population sample of young Black MSM (YBMSM) (N = 623). A network analytic technique called exponential random graph modeling was used in a proof of concept analysis to verify how each sex behavior increases the likelihood of a venue patronage tie when estimated as either: (1) an attribute of an individual only and/or (2) a shared attribute between an individual and his peers. Findings reveal that sex behaviors, when modeled only as attributes possessed by focal individuals, were no more or less likely to affect choices to visit social venues. However, when the sex behaviors of peers were also taken into consideration, we learn that individuals were statistically more likely in all three behavioral conditions to go places that attracted other MSM who practiced the same behaviors. This demonstrates that social venues can function as intermediary contexts in which relationships can form between individuals that have greater risk potential given the venues attraction to people who share the same risk tendencies. As such, structuring interventions around these settings can be an effective way to capture the attention of YBMSM and engage them in HIV prevention.

Marijuana Use Among Young Black Men Who Have Sex With Men and the HIV Care Continuum: Findings From the uConnect Cohort.

BACKGROUND: Young Black men who have sex with men (YBMSM) are at highest risk for HIV seroconversion in the United States. Successful movement through the HIV care continuum is an important intervention for limiting onwards HIV transmission. OBJECTIVE: Little data exists on how substances most commonly used by YBMSM, such as marijuana, are related to the HIV continuum, which represents the primary aim of this study. METHODS: A cohort of YBMSM (n = 618) was generated through respondent-driven sampling. Frequency of marijuana use and marijuana use as a sex-drug were assessed across the HIV care continuum using weighted logistic regression models. RESULTS: Study participants reported more intermittent marijuana use (n = 254, 56.2%) compared to heavy use (n = 198, 43.8%). Our sample contained 212 (34.3%) HIV seropositive participants of which 52 (24.5%) were unaware of their HIV positive status. Study participants who were heavy marijuana users were more likely to be unaware of their HIV seropositive status (AOR: 4.18; 95% CI 1.26, 13.89). All other stages in the care continuum demonstrated no significant differences between those who use marijuana intermittently or heavily or as a sex-drug and nonusers. CONCLUSIONS: YBMSM who used marijuana heavily were more likely to be HIV-positive unaware than those who never used marijuana. Findings were inconclusive regarding the relationships between marijuana use and other HIV care continuum metrics. However, knowledge of ones' HIV status is a critical requirement for engaging in care and may have implications for onwards HIV transmission.

Conceptual framework and research methods for migration and HIV transmission dynamics.

Migration and mobility have had a profound influence on the global HIV epidemic. We propose a network-dyadic conceptual model to interpret previous literature and inform the development of future research with respect to study design, measurement methods, and analytic approach. In this model, HIV transmission is driven by risk behaviors of migrants that emerges and is enabled by mobility, the bridging of sub-epidemics across space and time, and the displacement effects on the primary residential sending community for migrants. To investigate these causal pathways, empirical study designs must measure the relative timing of migratory events, sexual risk behaviors, and incident HIV infections. Network-based mathematical models using empirical data on partnerships help gain insight into the dynamic disease transmission systems. Although the network-dyadic conceptual model and related network methods may not address all questions related to migration and HIV, they provide a unified approach for future research on this important topic.

Modeling the impact of post-diagnosis behavior change on HIV prevalence in Southern California men who have sex with men (MSM).

Our objective here is to demonstrate the population-level effects of individual-level post-diagnosis behavior change (PDBC) in Southern Californian men who have sex with men (MSM), recently diagnosed with HIV. While PDBC has been empirically documented, the population-level effects of such behavior change are largely unknown. To examine these effects, we develop network models derived from the exponential random graph model family. We parameterize our models using behavioral data from the Southern California Acute Infection and Early Disease Research Program, and biological data from a number of published sources. Our models incorporate vital demographic processes, biology, treatment and behavior. We find that without PDBC, HIV prevalence among MSM would be significantly higher at any reasonable frequency of testing. We also demonstrate that higher levels of HIV risk behavior among HIV-positive men relative to HIV-negative men observed in some cross-sectional studies are consistent with individual-level PDBC.

Impact of post-incarceration care engagement interventions on HIV transmission among young Black men who have sex with men and their sexual partners: an agent-based network modeling study.

Background: Understanding the impact of incarceration on HIV transmission among Black men who have sex with men is important given their disproportionate representation among people experiencing incarceration and the potential impact of incarceration on social and sexual networks, employment, housing, and medical care. We developed an agent-based network model (ABNM) of 10,000 agents representing young Black men who have sex with men in the city of Chicago to examine the impact of varying degrees of post-incarceration care disruption and care engagement interventions following release from jail on HIV incidence. Methods: Exponential random graph models were used to model network formation and dissolution dynamics, and network dynamics and HIV care continuum engagement were varied according to incarceration status. Hypothetical interventions to improve post-release engagement in HIV care for individuals with incarceration (e.g., enhanced case management, linkage to housing and employment services) were compared to a control scenario with no change in HIV care engagement after release. Finding: HIV incidence at 10 years was 4.98 [95% simulation interval (SI): 4.87, 5.09 per 100 person-years (py)] in the model population overall; 5.58 (95% SI 5.38, 5.76 per 100 py) among those with history of incarceration, and 12.86 (95% SI 11.89, 13.73 per 100 py) among partners of agents recently released from incarceration. Sustained post-release HIV care for agents with HIV and experiencing recent incarceration resulted in a 46% reduction in HIV incidence among post-incarceration partners [incidence rate (IR) per 100 py = 5.72 (95% SI 5.19, 6.27) vs. 10.61 (95% SI 10.09, 11.24); incidence rate ratio (IRR) = 0.54; (95% SI 0.48, 0.60)] and a 19% reduction in HIV incidence in the population overall [(IR per 100 py = 3.89 (95% SI 3.81-3.99) vs. 4.83 (95% SI 4.73, 4.92); IRR = 0.81 (95% SI 0.78, 0.83)] compared to a scenario with no change in HIV care engagement from pre-to post-release. Interpretation: Developing effective and scalable interventions to increase HIV care engagement among individuals experiencing recent incarceration and their sexual partners is needed to reduce HIV transmission among Black men who have sex with men. Funding: This work was supported by the following grants from the National Institutes of Health: R01DA039934; P20 GM 130414; P30 AI 042853; P30MH058107; T32 DA 043469; U2C DA050098 and the California HIV/AIDS Research Program: OS17-LA-003; H21PC3466.

Stimulant use interventions may strengthen 'Getting to Zero' HIV elimination initiatives in Illinois: Insights from a modeling study.

OBJECTIVE(S): Getting to Zero (GTZ) is an Illinois-based HIV elimination initiative. GTZ identifies younger Black men who have sex with men (YBMSM) as a population who have experienced disproportionate HIV incidence. Rising stimulant use among YBMSM has been determined to impede engagement in the HIV prevention and treatment continua for reducing onward HIV transmission. Given the limited development of dedicated or culturally appropriate interventions for this population, this modeling study explores the impact of stimulant use on HIV incidence among YBMSM and assesses the impact of interventions to treat stimulant use on downstream HIV transmission to achieve GTZ goals. METHODS: A previously developed agent-based network model (ABNM), calibrated using data for YBMSM in Illinois, was extended to incorporate the impact of stimulant use (methamphetamines, crack/cocaine, and ecstasy) on sexual networks and engagement in HIV treatment and prevention continua. The model simulated the impact of a residential behavioral intervention (BI) for reducing stimulant use and an outpatient biomedical intervention (mirtazapine) for treating methamphetamine use. The downstream impact of these interventions on population-level HIV incidence was the primary intervention outcome. RESULTS: Baseline simulated annual HIV incidence in the ABNM was 6.93 [95% Uncertainty Interval (UI): 6.83,7.04] per 100 person years (py) and 453 [95% UI: 445.9,461.2] new infections annually. A residential rehabilitation intervention targeted to 25% of stimulant using persons yielded a 27.1% reduction in the annual number of new infections. Initiating about 50% of methamphetamine using persons on mirtazapine reduced the overall HIV incidence among YBMSM by about 11.2%. A 30% increase in antiretroviral treatment (ART) and preexposure prophylaxis (PrEP) uptake in the non-stimulant using YBMSM population combined with a 25% uptake of BI for stimulant using persons produces an HIV incidence consistent with HIV elimination targets (about 200 infections/year) identified in the GTZ initiative. CONCLUSIONS: Behavioral and biomedical interventions to treat stimulant use, in addition to expanding overall ART and PrEP uptake, are likely to enhance progress towards achieving GTZ goals.

Impact of changes in protective behaviors and out-of-household activities by age on COVID-19 transmission and hospitalization in Chicago, Illinois.

PURPOSE: Even with an efficacious vaccine, protective behaviors (social distancing, masking) are essential for preventing COVID-19 transmission and could become even more important if current or future variants evade immunity from vaccines or prior infection. METHODS: We created an agent-based model representing the Chicago population and conducted experiments to determine the effects of varying adult out-of-household activities (OOHA), school reopening, and protective behaviors across age groups on COVID-19 transmission and hospitalizations. RESULTS: From September-November 2020, decreasing adult protective behaviors and increasing adult OOHA both substantially impacted COVID-19 outcomes; school reopening had relatively little impact when adult protective behaviors and OOHA were maintained. As of November 1, 2020, a 50% reduction in young adult (age 18-40) protective behaviors resulted in increased latent infection prevalence per 100,000 from 15.93 (IQR 6.18, 36.23) to 40.06 (IQR 14.65, 85.21) and 19.87 (IQR 6.83, 46.83) to 47.74 (IQR 18.89, 118.77) with 15% and 45% school reopening. Increasing adult (age ≥18) OOHA from 65% to 80% of prepandemic levels resulted in increased latent infection prevalence per 100,000 from 35.18 (IQR 13.59, 75.00) to 69.84 (IQR 33.27, 145.89) and 38.17 (IQR 15.84, 91.16) to 80.02 (IQR 30.91, 186.63) with 15% and 45% school reopening. Similar patterns were observed for hospitalizations. CONCLUSIONS: In areas without widespread vaccination coverage, interventions to maintain adherence to protective behaviors, particularly among younger adults and in out-of-household settings, remain a priority for preventing COVID-19 transmission.