Effectiveness of BNT162b2 BA.4/5 Bivalent mRNA Vaccine Against Symptomatic COVID-19 Among Immunocompetent Individuals Testing at a Large US Retail Pharmacy.

BACKGROUND: Data on the effectiveness of BA.4/5 bivalent vaccine stratified by age and prior infection are lacking. METHODS: This test-negative study used data from individuals ≥5 years of age testing for SARS-CoV-2 with symptoms (15 September 2022 to 31 January 2023) at a large national retail pharmacy chain. The exposure was receipt of 2-4 wild-type doses and a BNT162b2 BA.4/5 bivalent vaccine (>2 months since last wild-type dose). The outcome was a positive SARS-CoV-2 test. Absolute (vs unvaccinated) and relative (vs 2-4 wild-type doses) vaccine effectiveness (VE) were calculated as (1 - adjusted odds ratio from logistic regression) × 100. VE was stratified by age and self-reported prior infection. RESULTS: Overall, 307 885 SARS-CoV-2 tests were included (7916 aged 5-11, 16 329 aged 12-17, and 283 640 aged ≥18 years). SARS-CoV-2 positivity was 39%; 21% were unvaccinated, 70% received 2-4 wild-type doses with no bivalent vaccine, and 9% received a BNT162b2 BA.4/5 bivalent dose. At a median of 1-2 months after BNT162b2 BA.4/5 bivalent vaccination, depending on age group, absolute VE was 22%-60% and was significantly higher among those reporting prior infection (range, 55%-79%) than not (range, no protection to 50%). Relative VE was 31%-64%. CONCLUSIONS: BNT162b2 BA.4/5 bivalent showed early additional protection against Omicron-related symptomatic COVID-19, with hybrid immunity offering greater protection.

Evaluation of respondent-driven sampling in seven studies of people who use drugs from rural populations: findings from the Rural Opioid Initiative.

BACKGROUND: Accurate prevalence estimates of drug use and its harms are important to characterize burden and develop interventions to reduce negative health outcomes and disparities. Lack of a sampling frame for marginalized/stigmatized populations, including persons who use drugs (PWUD) in rural settings, makes this challenging. Respondent-driven sampling (RDS) is frequently used to recruit PWUD. However, the validity of RDS-generated population-level prevalence estimates relies on assumptions that should be evaluated. METHODS: RDS was used to recruit PWUD across seven Rural Opioid Initiative studies between 2018-2020. To evaluate RDS assumptions, we computed recruitment homophily and design effects, generated convergence and bottleneck plots, and tested for recruitment and degree differences. We compared sample proportions with three RDS-adjusted estimators (two variations of RDS-I and RDS-II) for five variables of interest (past 30-day use of heroin, fentanyl, and methamphetamine; past 6-month homelessness; and being positive for hepatitis C virus (HCV) antibody) using linear regression with robust confidence intervals. We compared regression estimates for the associations between HCV positive antibody status and (a) heroin use, (b) fentanyl use, and (c) age using RDS-1 and RDS-II probability weights and no weights using logistic and modified Poisson regression and random-effects meta-analyses. RESULTS: Among 2,842 PWUD, median age was 34 years and 43% were female. Most participants (54%) reported opioids as their drug of choice, however regional differences were present (e.g., methamphetamine range: 4-52%). Many recruitment chains were not long enough to achieve sample equilibrium. Recruitment homophily was present for some variables. Differences with respect to recruitment and degree varied across studies. Prevalence estimates varied only slightly with different RDS weighting approaches, most confidence intervals overlapped. Variations in measures of association varied little based on weighting approach. CONCLUSIONS: RDS was a useful recruitment tool for PWUD in rural settings. However, several violations of key RDS assumptions were observed which slightly impacts estimation of proportion although not associations.

Overdose responses among rural people who use drugs: A multi-regional qualitative study.

BACKGROUND: Efforts to distribute naloxone have equipped more people with the ability to reverse opioid overdoses but people who use drugs are often reluctant to call 911 due to concerns for legal repercussions. Rural communities face unique challenges in reducing overdose deaths compared to urban communities, including limited access to harm reduction services as well as greater concerns about stigma and privacy. METHODS: The Rural Opioid Initiative was funded in 2017 to better understand the health-related harms associated with the opioid crisis in rural US communities and consists of eight studies spanning ten states and 65 counties. Each study conducted semi-structured qualitative interviews with people who use drugs to understand contextual factors influencing drug use and health behaviors. We analyzed qualitative data from seven studies with data available at the time of analysis to understand peer response to overdose. RESULTS: Of the 304 participants interviewed, 55% were men, 70% were white, 80% reported current injection drug use, and 60% reported methamphetamine use. Similar to what has been found in studies focused on urban settings, people who use drugs in rural communities use a range of strategies to reverse overdoses, including non-evidence-based approaches. Several reported that multiple doses of naloxone are needed to reverse overdose. Three themes emerged around the willingness to call 911, including (1) hesitancy to call 911 for fear of legal consequences, (2) negative perceptions or experiences with law enforcement officers, and (3) efforts to obtain medical intervention while avoiding identification/law enforcement involvement. CONCLUSION: People who use drugs employ multiple strategies to attempt overdose reversal, including non-evidence-based approaches. Greater education about the most effective and least harmful strategies is needed. Reluctance to call 911 is rooted in concerns about potential legal consequences as well as perceptions about law enforcement officers, which may be heightened in rural communities where people who use drugs are more easily identified by law enforcement. People who use drugs will go to great strides to connect their peers to needed medical services, suggesting that comprehensive interventions to reduce interactions with law enforcement officers and eliminate legal consequences for reporting overdoses are critical.

Characterising a syndemic among black women at risk for HIV: the role of sociostructural inequity and adverse childhood experiences.

Objectives Black women disproportionately experience STIs (including HIV/AIDS), gender-based violence, substance misuse and mental health conditions. Addressing a gap in syndemic research, we characterised comorbidity overlap within the context of sociostructural inequities and adverse childhood experiences (ACEs) among black women in Baltimore, Maryland. Methods Between 2015 and 2018, black women (n=305) were recruited from STI clinics in Baltimore, Maryland. Among those with complete survey data (n=230), we conducted a latent class analysis to differentiate women based on their profile of the following syndemic comorbidities: STIs, adult sexual victimisation, substance misuse and mental health disorders. We then examined the association between ACEs and syndemic latent class membership. Results Thirty-three percent of women experienced three to nine ACEs before age 18 years, and 44% reported four to six comorbidities. The two-class latent class solution demonstrated the best fit model, and women were categorised in either class 1 (past-year STI; 59%) or class 2 (syndemic comorbidities; 41%). Women in class 2 were more likely to report unstable housing (10% vs 3%) and identify as bisexual/gay (22% vs 10%) than women in class 1. ACEs were significantly associated with an increased likelihood of class 2 membership. Conclusions This study reinforces the importance of screening for ACEs and offering trauma-informed, integrated care for black women with syndemic comorbidities. It also highlights the critical nature of tailoring interventions to improve sociostructural equity, preventing and reducing syndemic development.

Network Correlates of Using a Syringe After an Injection Partner Among Women Who Inject Drugs in Philadelphia Pennsylvania.

This analysis aims to identify relationship-level correlates of receptive syringe sharing among women who inject drugs in Philadelphia. Sixty-four women who injected daily were recruited from Prevention Point Philadelphia's syringe exchange program (9/2/20 - 11/23/20). Interviewer-administered surveys collected (1) individual-level demographics and risk behaviors and (2) relationship-level information about each past-6-month injection partner and injecting practices between the two. We built two separate log-binomial regression models which accounted for clustering of network members within participants to identify relationship-level correlates of using a syringe after a partner. Women reported injecting with a syringe previously used by 21.14% of partners. Women were more likely to use a syringe after sex partners (Adjusted Prevalence Ratio [APR]model_1=2.77) and those who provided injection assistance (APRmodel_1=1.92) or emotional support (APRmodel_2=6.19). Future harm reduction efforts could train women to negotiate safer injection practices with sex partners and those who provide injection assistance and/or emotional support.

RESUMEN: Este análisis tiene como objetivo identificar los correlatos a nivel de relación del compartimiento de jeringas receptivas en las mujeres que se inyectan drogas en Filadelfia. Sesenta y cuatro mujeres que se inyectaron diariamente fueron reclutadas en el programa de intercambio de jeringas de Prevention Point Philadelphia (9/2/20 − 11/23/20). Las encuestas fueron administradas por un entrevistador y recabaron (1) características demográficas y comportamientos de riesgo a nivel del individuo y (2) información sobre la relación con cada pareja de inyección durante los últimos 6 meses, incluidas las prácticas de inyección entre los dos. Construimos dos modelos de regresión logarítmico-binomial separados que representaban la agrupación de miembros de la red dentro de los participantes para identificar correlatos a nivel de relación del uso de una jeringa después de una pareja. Las mujeres utilizaron una jeringa que había sido utilizada previamente por 21.14% de las parejas de inyección enumeradas. Las mujeres eran más probables en usar una jeringa después de las parejas sexuales (Razón de prevalencia ajustada [RPA]model_1 = 2.77) y de quienes las ayudaron a inyectarse (RPAmodel_1 = 1.92) o les brindaron apoyo emocional (RPAmodel_2 = 6.19). Los esfuerzos futuros de reducción del daño podrían capacitar a las mujeres para negociar prácticas de inyección más seguras con sus parejas sexuales y quienes brindan asistencia para la inyección y/o apoyo emocional.

Potential Impact of Telemedicine for Medication Abortion Policy and Programming Changes on Abortion Accessibility in the United States.

Objectives. To quantify the impact of telemedicine for medication abortion (TMAB) expansion or ban removal on abortion accessibility. Methods. We included 1091 facilities from the 2018 Advancing New Standards in Reproductive Health facility database and Planned Parenthood Web site, among which 241 did not offer abortion as sites for TMAB expansion. Accessibility was defined as the proportion of reproductive-aged women living within a 30-, 60-, or 90-minute drive time from an abortion-providing facility. We calculated accessibility differences between 3 scenarios: (1) facilities offering abortion in 2018 (reference), (2) the reference scenario in addition to all facilities in states without TMAB bans (TMAB expansion), and (3) all facilities (TMAB ban removal). We also stratified by state and urban-rural status. Results. In 2018, 65%, 81%, and 89% of women lived within a 30-, 60-, or 90-minute drive time from an abortion-providing facility, respectively. Expansion and ban removal expanded abortion accessibility relative to the current accessibility scenario (range: 1.25-5.66 percentage points). Women in rural blocks experienced greater increases in accessibility than those in urban blocks. Conclusions. TMAB program and policy changes could expand abortion accessibility to an additional 3.5 million reproductive-aged women. Public Health Implications. Our findings can inform where to invest resources to improve abortion accessibility. (Am J Public Health. 2022;112(8):1202-1211. https://doi.org/10.2105/AJPH.2022.306876).

Perceived HIV Treatment Norms Modify the Association Between HIV-Related Stigma and Adherence to Antiretroviral Therapy Among Persons Living with HIV in Baltimore, Maryland.

Adherence to antiretroviral therapy (ART) is associated with reduced HIV-related morbidity/mortality and ongoing transmission; however, the extent to which this association is modified by perceived HIV treatment norms is unknown. 270 PLWH completed a survey to assess demographics, risk behaviors, stigma, ART adherence, and perceived HIV treatment norms (Baltimore, 2014-2017). We used modified Poisson regression to examine effect modification by perceived HIV treatment norms. The association between HIV-related stigma and ART adherence was modified by perceived HIV treatment norms. Among individuals who perceived that friends/family were sub-optimally adherent, HIV-related stigma was negatively associated with ART adherence (Adjusted Risk Ratio [ARR] = 0.36; 95%CI 0.15-0.87). Among those who perceived optimal adherence among friends/family, the relationship between HIV-related stigma and ART adherence was not statistically significant (ARR = 1.07; 95%CI 0.65-1.76). Interventions to improve ART adherence among those who are sub-optimally adherent could focus on increasing perceptions of ART adherence among their friends/family.

RESUMEN: La adherencia al tratamiento antirretroviral está asociada con la reducción de la morbilidad y mortalidad relacionada con el VIH y su transmisión; sin embargo, no se sabe hasta qué punto esta asociación se modificada por las normas percibidas sobre el tratamiento del VIH. 270 personas que viven con el VIH completaron una encuesta para evaluar las características demográficas, los comportamientos de riesgo, el estigma, la adherencia a los tratamientos antiretrovirales y las normas percibidas sobre el tratamiento del VIH (Baltimore, 2014­2017). Se utilizó una regresión de Poisson modificada para examinar la modificación del efecto por las normas percibidas sobre el tratamiento del VIH. La asociación entre el estigma relacionada con el VIH y la adherencia al tratamiento antirretroviral fue modificada por las normas percibidas de tratamiento del VIH. Entre los individuos que percibían que sus amigos/familiares no se adhirieron al tratamiento antirretroviral de manera óptima, el estigma relacionada con el VIH se asoció negativamente con la adherencia al tratamiento antirretroviral (Razón de riesgo ajustada [RRA] = 0.36; IC 95%:0.15­0.87). Entre los que percibían que sus amigos(as)/familiares se adhirieron al tratamiento del VIH de manera óptima, la asociación entre el estigma relacionada con el VIH y la adherencia al tratamiento antirretroviral no fue estadísticamente significativa (RRA = 1.07; IC 95%:0.65­1.76). Las intervenciones para mejorar la adherencia al tratamiento antirretroviral para aquellos que no se adhieren al tratamiento de manera óptima podrían centrarse en mejorar las normas percibidas sobre la adherencia al tratamiento antirretroviral entre sus amigos(as) y familiares.

Integrating a web-based survey application into Qualtrics to collect risk location data for HIV prevention research.

Aspects of the physical and social environment play an important role in shaping HIV-related risk/prevention behaviors and access to prevention and treatment services. Here, we describe the feasibility of integrating a web-based survey application to collect risk locations into Qualtrics and compare this approach with a JavaScript-based alternative. Between 2017 and 2018, we enrolled 29 persons living with HIV in Boston Massachusetts to complete an interviewer-administered questionnaire using Qualtrics. Surveys collected demographics; sex/drug use risk behaviors; locations where participants met sex partners, had condomless sex, attended group sex events, and shared a syringe or injection equipment with someone else (up to 10 locations each); and the locations where participants (a) had sex with each sex partner (past 6 months) and (b) used drugs with each drug use partner (past 6 months). Location data were collected using embedded links to an encrypted web-based survey application. Overall, participants provided valid coordinates 93% of the time; when an exact location was not provided, a neighborhood was provided instead, resulting in little missing data. Our findings suggest that this web-based data collection tool (alone or with embedded links in Qualtrics) is a feasible and secure option for collecting risk location data.

Privacy and Confidentiality Considerations for Collecting HIV Risk Network Data among Men who Have Sex with Men and Implications for Constructing Valid Risk Networks.

Studies aiming to construct risk networks have historically collected network members' names, demographic characteristics and relational data (i.e., type, strength, duration, frequency of interaction, and HIV-related risk behaviors between the pair). Due to difficulties in constructing risk networks stemming from partner anonymity and the use of nicknames, some studies also collect network members' screen names, phone numbers, physical attributes, and scars/tattoos to assist with entity resolution. In-depth interviews with 20 men who have sex with men and transgender women in Kentucky assessed privacy/confidentiality concerns as well as accuracy/recall issues associated with providing these details. Most preferred providing alters' nicknames/first names only or a first name with the first letter of the last name. Many perceived screen names, phone numbers, and scars/tattoos to be too personal/identifying. Willingness to provide more detailed information varied by relationship type/strength, which could influence the validity of the resulting network.

Privacy, Confidentiality, and Safety Considerations for Conducting Geographic Momentary Assessment Studies Among Persons Who Use Drugs and Men Who Have Sex with Men.

Geographic momentary assessments (GMA) collect real-time behavioral data in one's natural environment using a smartphone and could potentially increase the ecological validity of behavioral data. Several studies have evaluated the feasibility and acceptability of GMA among persons who use drugs (PWUD) and men who have sex with men (MSM), but fewer have discussed privacy, confidentiality, and safety concerns, particularly when illegal or stigmatized behavioral data were collected. This study explores perceptions regarding privacy, confidentiality, and safety of GMA research among PWUD and MSM recruited in three different settings (rural Appalachia, a mid-sized city in the South, and a mid-Atlantic city). Between November 2014 and April 2017, we recruited 35 PWUD from rural Appalachian Kentucky (N = 20) and Baltimore, Maryland (N = 15) and 20 MSM from Lexington, Kentucky to complete semi-structured qualitative interviews. Through thematic analyses, we identified and compared privacy, confidentiality, and safety concerns by demographic characteristics, risk behaviors, and setting. Privacy, confidentiality, and safety concerns varied by setting, age, smartphone ownership, use of illegal drugs, and history of drug-related arrests. Among those who used drugs, participants reported concerns with being tracked and burden associated with carrying and safeguarding study phones and responding to survey prompts. Privacy and confidentiality concerns were noted in each setting, but tracking concerns were greatest among Baltimore participants and led many to feel that they (or others) would be unwilling to participate or comply with study procedures. While locations considered to be sensitive varied by setting, participants in all settings said they would take measures to prevent sensitive information from being collected (i.e., intentionally disable devices, leave phones at home, alter response times). Privacy, confidentiality, and safety concerns may limit the accuracy of risk location information, study compliance, and participation. As concerns were often greatest among those engaging in illegal behaviors and with the highest risk behaviors, selection bias and non-response bias could negatively influence the representativeness and validity of study findings.

Using Network and Spatial Data to Better Target Overdose Prevention Strategies in Rural Appalachia.

This analysis uses network and spatial data to identify optimal individuals to target with overdose prevention interventions in rural Appalachia. Five hundred and three rural persons who use drugs were recruited to participate in the Social Networks among Appalachian People Study (2008-2010). Interviewer-administered surveys collected information on demographic characteristics, risk behaviors (including overdose history), network members, and residential addresses. We restricted the sample to individuals with at least one confirmed relationship to another study participant (N = 463). Using dyadic analyses (N = 1428 relationships), we identified relationship-level correlates of relationships with network members who have previously overdosed. We then examined individual- and network-level factors associated with (1) having at least one first-degree alter (i.e., network member) with a prior overdose and (2) each additional network member with a prior overdose (N = 463 study participants). Overall, 28% of the sample had previously overdosed and 57% were one-degree away from someone who previously overdosed. Relationships with those who had overdosed were characterized by closer residential proximity. Those with at least one network member who previously overdosed were more geographically central and occupied more central network positions. Further, the number of network members with an overdose history increased with decreasing distance to the town center, increasing network centrality, and prior enrollment in an alcohol detox program. Because fatal overdoses can be prevented through bystander intervention, these findings suggest that strategies that target more central individuals (both geographically and based on their network positions) and those who have previously enrolled in alcohol detox programs with overdose prevention training and naloxone may optimize intervention reach and have the potential to curb overdose fatalities in this region.

Network-Based Research on Rural Opioid Use: an Overview of Methods and Lessons Learned.

PURPOSE OF REVIEW: The purpose of this paper is to provide a thorough overview of methods used for recruitment, network data collection, and network data management in a network-based study of rural people who use drugs (PWUD) and to offer methodological recommendations for future research on rural drug use. RECENT FINDINGS: The Social Networks among Appalachian People (SNAP) study recruited a cohort of 503 rural PWUD via respondent-driven sampling (RDS) and has retained more than 80% of eligible participants over 7-9 years. SNAP has yielded important methodological insights, including that (1) RDS referral was non-random and disproportionately involved kin and (2) interviewer-administered questionnaires were successful in eliciting accurate name and age information about network members. The SNAP experience suggests that RDS was a successful recruitment strategy for rural PWUD and questionnaires administered by community-based interviewers in the context of a Certificate of Confidentiality could elicit detailed data on PWUD risk networks.

Spatial Distribution of Partner-Seeking Men Who Have Sex With Men Using Geosocial Networking Apps: Epidemiologic Study.

BACKGROUND: Geosocial networking apps have made sexual partner-seeking easier for men who have sex with men, raising both challenges and opportunities for human immunodeficiency virus and sexually transmitted infection prevention and research. Most studies on men who have sex with men geosocial networking app use have been conducted in large urban areas, despite research indicating similar patterns of online- and app-based sex-seeking among men who have sex with men in rural and midsize cities. OBJECTIVE: The goal of our research was to examine the spatial distribution of geosocial networking app usage and characterize areas with increasing numbers of partner-seeking men who have sex with men in a midsize city in the South. METHODS: Data collection points (n=62) were spaced in 2-mile increments along 9 routes (112 miles) covering the county encompassing the city. At each point, staff logged into 3 different geosocial networking apps to record the number of geosocial networking app users within a 1-mile radius. Data were collected separately during weekday daytime (9:00 AM to 4:00 PM) and weekend nighttime (8:00 PM to 12:00 AM) hours. Empirical Bayesian kriging was used to create a raster estimating the number of app users throughout the county. Raster values were summarized for each of the county's 208 Census block groups and used as the outcome measure (ie, geosocial networking app usage). Negative binomial regression and Wilcoxon signed rank sum tests were used to examine Census block group variables (eg, median income, median age) associated with geosocial networking app usage and temporal differences in app usage, respectively. RESULTS: The number of geosocial networking app users within a 1-mile radius of the data collection points ranged from 0 to 36 during weekday daytime hours and 0 to 39 during weekend nighttime hours. In adjusted analyses, Census block group median income and percent Hispanic ethnicity were negatively associated with geosocial networking app usage for all 3 geosocial networking apps during weekday daytime and weekend nighttime hours. Population density and the presence of businesses were positively associated with geosocial networking app usage for all 3 geosocial networking apps during both times. CONCLUSIONS: In this midsize city, geosocial networking app usage was highest in areas that were more population-dense, were lower income, and had more businesses. This research is an example of how geosocial networking apps' geospatial capabilities can be used to better understand patterns of virtual partner-seeking among men who have sex with men.

Examining the Social Context of Injection Drug Use: Social Proximity to Persons Who Inject Drugs Versus Geographic Proximity to Persons Who Inject Drugs.

In this analysis, we used social network and spatial data to examine associations between people's drug injection status and their social and/or spatial proximity to others who injected drugs. We recruited 503 rural Kentucky residents who used drugs to participate in the Social Networks among Appalachian People (SNAP) Study (2008-2010). Interviewer-administered surveys collected information on recent (past 6 months) sex, drug-use, and social-support network members (n = 897 ties). Using network simulations, we determined a threshold for the association between social proximity to others who injected drugs and recent injection status ("socially proximal" was defined by a shortest path ≤2). We defined "geographically proximal" as the median road-network distance between pairs of individuals who both injected drugs (≤7 miles (≤11.2 km)). Logistic regression was used to determine the independent and joint associations between the number of socially and/or geographically proximal injecting peers and a person's injection status. After adjustment, the odds of recent injection increased by 0.4% for each injecting peer who was geographically proximal but not socially proximal, 12% for each geographically and socially proximal injecting peer, and 22% for each injecting peer who was socially proximal but not geographically proximal. When implementing network-based interventions which promote cessation of injection drug use, investigators should consider collecting sociometric network data to examine whether the intervention diffuses through the network and whether there are additive or threshold effects.

Multiplex Relationships and HIV: Implications for Network-Based Interventions.

The number of network members and the roles they play can influence risk behaviors and consequently intervention strategies to reduce HIV transmission. We recruited 652 people who use drugs (PWUD) from socially disadvantaged neighborhoods in New York City (07/2006-06/2009). Interviewer-administered surveys ascertained demographic, behavioral, and network data. We used logistic regression, stratified by exchange sex, to assess the relationship between HIV status and the number of network members with different roles, treated as independent and multiplex (i.e., drug + sex). Those with more multiplex risk ties were significantly more likely to be HIV positive, but only among those not reporting exchange sex (AOR = 3.2). Among those reporting exchange sex, men reporting recent male sex partners were more likely to report HIV positive status (AOR = 12.6). These data suggest that sex and drug relationships among PWUD are interrelated. Interventions that target multiplex rather than single-role relationships may be more effective in influencing behavior change.

Assessing the geographic coverage and spatial clustering of illicit drug users recruited through respondent-driven sampling in New York City.

We assess the geographic coverage and spatial clustering of drug users recruited through respondent-driven sampling (RDS) and discuss the potential for biased RDS prevalence estimates. Illicit drug users aged 18-40 were recruited through RDS (N = 401) and targeted street outreach (TSO) (N = 210) in New York City. Using the Google Maps API™, we calculated travel distances and times using public transportation between each participant's recruitment location and the study office and between RDS recruiter-recruit pairs. We used K function analysis to evaluate and compare spatial clustering of (1) RDS vs. TSO respondents and (2) RDS seeds vs. RDS peer recruits. All participant recruitment locations clustered around the study office; however, RDS participants were significantly more likely to be recruited within walking distance of the study office than TSO participants. The TSO sample was also less spatially clustered than the RDS sample, which likely reflects (1) the van's ability to increase the sample's geographic heterogeneity and (2) that more TSO than RDS participants were enrolled on the van. Among RDS participants, individuals recruited spatially proximal peers, geographic coverage did not increase as recruitment waves progressed, and peer recruits were not less spatially clustered than seeds. Using a mobile van to recruit participants had a greater impact on the geographic coverage and spatial dependence of the TSO than the RDS sample. Future studies should consider and evaluate the impact of the recruitment approach on the geographic/spatial representativeness of the sample and how spatial biases, including the preferential recruitment of proximal peers, could impact the precision and accuracy of estimates.

Polydrug Use and HIV Risk Among People Who Inject Heroin in Tijuana, Mexico: A Latent Class Analysis.

BACKGROUND: Although most people who inject drugs (PWID) in Tijuana, Mexico, primarily inject heroin, injection and non-injection use of methamphetamine and cocaine is common. We examined patterns of polydrug use among heroin injectors to inform prevention and treatment of drug use and its health and social consequences. METHODS: Participants were PWID residing in Tijuana, aged ≥18 years who reported heroin injection in the past six months and were recruited through respondent-driven sampling (n = 1,025). Latent class analysis was conducted to assign individuals to classes on a probabilistic basis, using four indicators of past six-month polydrug and polyroute use: cocaine injecting, cocaine smoking or snorting, methamphetamine injecting, and methamphetamine smoking or snorting. Latent class membership was regressed onto covariates in a multinomial logistic regression. RESULTS: Latent class analyses testing 1, 2, 3, and 4 classes were fit, with the 3-class solution fitting best. Class 1 was defined by predominantly heroin use (50.2%, n = 515); class 2 by methamphetamine and heroin use (43.7%, n = 448), and class 3 by methamphetamine, cocaine, and heroin use (6.0%, n = 62). Bivariate and multivariate analyses indicated a group of methamphetamine and cocaine users that exhibited higher-risk sexual practices and lower heroin injecting frequency, and a group of methamphetamine users who were younger and more likely to be female. CONCLUSIONS: Discrete subtypes of heroin PWID were identified based on methamphetamine and cocaine use patterns. These findings have identified subtypes of heroin injectors who require more tailored interventions to reduce the health and social harms of injecting drug use.

Nonprescription syringe sales: a missed opportunity for HIV prevention in California.

OBJECTIVE: To assess implementation of California Senate Bill SB41 in two inland California counties where prevalence of injection drug use is among the highest in the nation. DESIGN: Syringe purchase trial. SETTING: Fresno and Kern counties, California. PARTICIPANTS: All 248 community pharmacies in the counties. MAIN OUTCOME MEASURE: Successful or unsuccessful syringe purchase attempt. RESULTS: Only 52 (21.0%) syringe purchase attempts were successful. The proportion of successful attempts did not vary by county or by data collector ethnicity. The most common reasons for unsuccessful syringe purchase attempts were prescription requirements (45.7%), the requested syringe size was not available (10.7%), and the pharmacy did not sell syringes (9.7%). In addition, some syringe purchase attempts (4.1%) were unsuccessful because the data collector was asked to purchase more syringes than allowed by law. Although 80% and 78% of Fresno and Kern residents, respectively, live within a 5-minute drive of a community pharmacy, less than one-half live within a 5-minute drive of a community pharmacy that sold syringes. CONCLUSION: SB41 has not resulted in broad pharmacy-based syringe access in California's inland counties, where a disproportionate number of cases of human immunodeficiency virus (HIV) infections are associated with injection drug use. Additional steps by legislative bodies, regulatory agencies, and professional organizations are needed to actively engage pharmacies in expanding nonprescription syringe sales to reduce HIV transmission among injection drug users.

Incidence and prevalence of intrasubtype HIV-1 dual infection in at-risk men in the United States.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) dual infection (DI) has been associated with decreased CD4 T-cell counts and increased viral loads; however, the frequency of intrasubtype DI is poorly understood. We used ultradeep sequencing (UDS) to estimate the frequency of DI in a primary infection cohort of predominantly men who have sex with men (MSM). METHODS: HIV-1 genomes from longitudinal blood samples of recently infected, therapy-naive participants were interrogated with UDS. DI was confirmed when maximum sequence divergence was excessive and supported by phylogenetic analysis. Coinfection was defined as DI at baseline; superinfection was monoinfection at baseline and DI at a later time point. RESULTS: Of 118 participants, 7 were coinfected and 10 acquired superinfection. Superinfection incidence rate was 4.96 per 100 person-years (95% confidence interval [CI], 2.67-9.22); 6 occurred in the first year and 4 in the second. Overall cumulative prevalence of intrasubtype B DI was 14.4% (95% CI, 8.6%-22.1%). Primary HIV-1 incidence was 4.37 per 100 person-years (95% CI, 3.56-5.36). CONCLUSIONS: Intrasubtype DI was frequent and comparable to primary infection rates among MSM in San Diego; however, superinfection rates declined over time. DI is likely an important component of the HIV epidemic dynamics, and development of stronger immune responses to the initial infection may protect from superinfection.