Background Mean active degree is an important proxy measure of cross-sectional network connectivity commonly used in HIV/STI 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 U.S. (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 0–12 prior to the survey date (retrospective method), and compared that to 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 0–12 months prior to survey date. This was driven by data truncation: among participants with >5 partners in the past year compared to those with ≤5, the average change in main partnership degree between 12 and 0 months prior to survey date was −0.05 (95% CI: −0.08, −0.03) after adjusting for race/ethnicity, age, and education. The adjusted average change in casual partnership degree was −0.40 (95% CI: −0.45, −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.

Objective: To evaluate if community-level HIV PrEP coverage is correlated with individual sexual behaviors. Design: We used demographic, behavioral, and sexual network data from ARTnet, a 2017–2019 study of US MSM. Methods: Multivariable regression models with a Bayesian modeling framework were used to estimate associations between area-level PrEP coverage and seven sexual behavior outcomes (number of total, main, and casual male partners [network degree]; count of one-time partnerships; consistent condom use in one-time partnerships; and frequency of casual partnership anal sex (total and condomless)), controlling for individual PrEP use. Results: PrEP coverage ranged from 10.3% (Philadelphia) to 38.9% (San Francisco). Total degree was highest in Miami (1.35) and lowest in Denver (0.78), while the count of one-time partners was highest in San Francisco (11.7/year) and lowest in Detroit (1.5/year). Adjusting for individual PrEP use and demographics, community PrEP coverage correlated with total degree (aIRR=1.73; 95% CrI, 0.92–3.44), casual degree (aIRR=2.05; 95% CrI, 0.90–5.07), and count of one-time partnerships (aIRR=1.90; 95% CrI, 0.46–8.54). Without adjustment for individual PrEP use, these associations strengthened. There were weaker or no associations with consistent condom use in one-time partnerships (aIRR=1.68; 95% CrI, 0.86–3.35), main degree (aIRR=1.21; 95% CrI, 0.48–3.20), and frequency of casual partnership condomless anal sex (aIRR=0.23; 95% CrI, 0.01–3.60). Conclusion: Most correlations between community PrEP coverage and sexual behavior were explained by individual PrEP use. However, some residual associations remained after controlling for individual PrEP use, suggesting that PrEP coverage may partially drive community-level differences in sexual behaviors.

Background: Population-level estimates of sexual network mixing for parameterizing prediction models of pre-exposure prophylaxis (PrEP) effectiveness are needed to inform prevention of HIV transmission among men who have sex with men (MSM). Estimates obtained by egocentric sampling are vulnerable to information bias due to incomplete respondent knowledge. Methods: We estimated patterns of serosorting and PrEP sorting among MSM in the United States using data from a 2017–2019 egocentric sexual network study. Respondents served as proxies to report the HIV status and PrEP use of recent sexual partners. We contrasted results from a complete-case analysis (unknown HIV and PrEP excluded) versus a bias analysis with respondent-reported data stochastically reclassified to simulate unobserved self-reported data from sexual partners. Results: We found strong evidence of preferential partnering across analytical approaches. The bias analysis showed concordance between sexual partners of HIV diagnosis and PrEP use statuses for MSM with diagnosed HIV (39%; 95% simulation interval: 31, 46), MSM who used PrEP (32%; 21, 37), and MSM who did not use PrEP (83%; 79, 87). The fraction of partners with diagnosed HIV was higher among MSM who used PrEP (11%; 9, 14) compared to MSM who did not use PrEP (4%; 3, 5). Comparatively, across all strata of respondents, the complete-case analysis overestimated the fractions of partners with diagnosed HIV or PrEP use. Conclusion: We found evidence consistent with HIV and PrEP sorting among MSM, which may decrease the population-level effectiveness of PrEP. Bias analyses can improve mixing estimates for parameterization of transmission models.

Background In custodial settings such as jails and prisons, infectious disease transmission is heightened by factors such as overcrowding and limited healthcare access. Specific features of social contact networks within these settings have not been sufficiently characterized, especially in the context of a large-scale respiratory infectious disease outbreak. The study aims to quantify contact network dynamics within the Fulton County Jail in Atlanta, Georgia, to improve our understanding respiratory disease spread to informs public health interventions. Methods As part of the Surveillance by Wastewater and Nasal Self-collection of Specimens (SWANSS) study, jail roster data were utilized to construct social contact networks. Rosters included resident details, cell locations, and demographic information. This analysis involved 6,702 residents over 140,901 person days. Network statistics, including degree, mixing, and turnover rates, were assessed across age groups, race/ethnicities, and jail floors. We compared outcomes for two distinct periods (January 2022 and April 2022) to understand potential responses in network structures during and after the SARS-CoV-2 Omicron variant peak. Results We found high cross-sectional network degree at both cell and block levels, indicative of substantial daily contacts. While mean degree increased with age, older residents exhibited lower degree during the Omicron peak, suggesting potential quarantine measures. Block-level networks demonstrated higher mean degrees than cell-level networks. Cumulative degree distributions for both levels increased from January to April, indicating heightened contacts after the outbreak. Assortative age mixing was strong, especially for residents aged 20–29. Dynamic network statistics illustrated increased degrees over time, emphasizing the potential for disease spread, albeit with a lower growth rate during the Omicron peak. Conclusions The contact networks within the Fulton County Jail presented ideal conditions for infectious disease transmission. Despite some reduction in network characteristics during the Omicron peak, the potential for disease spread remained high. Age-specific mixing patterns suggested unintentional age segregation, potentially limiting disease spread to older residents. The study underscores the need for ongoing monitoring of contact networks in carceral settings and provides valuable insights for epidemic modeling and intervention strategies, including quarantine, depopulation, and vaccination. This network analysis offers a foundation for understanding disease dynamics in carceral environments.

The uptake of COVID-19 vaccines remains low despite their high effectiveness. Epidemic models that represent decision-making psychology can provide insight into the potential impact of vaccine promotion interventions in the context of the COVID-19 pandemic. We coupled a network-based mathematical model of SARS-CoV-2 transmission in Georgia, USA with a social-psychological vaccination decision-making model in which vaccine side effects, post-vaccination infections, and other unidentified community-level factors could “nudge” individuals towards vaccine resistance while hospitalization spikes could nudge them towards willingness. Combining an increased probability of hospitalization-prompted resistant-to-willing switches with a decreased probability of willing-to-resistant switches prompted by unidentified community-level factors increased vaccine uptake and decreased SARS-CoV-2 incidence by as much as 30.7% and 24.0%, respectively. The latter probability had a greater impact than the former. This illustrates the disease prevention potential of vaccine promotion interventions that address community-level factors influencing decision-making and anticipate the case curve instead of reacting to it.

Background: Previous models have estimated the total population attributable fraction of NG/CT on HIV incidence among men who have sex with men (MSM), but this does not represent realistic intervention effects. We estimated the potential impact of screening for NG/CT on downstream incidence of HIV among MSM. Methods: Using a network model, we estimated the effects of varying coverage levels for STI screening among different priority populations: all sexually active MSM regardless of HIV serostatus, MSM with multiple recent (past 6 months) sex partners regardless of serostatus, MSM without HIV, and MSM with HIV. Under the assumption that all screening events included a urethral test, we also examined the effect of increasing of the proportion of screening events that include rectal screening for NG/CT on HIV incidence. Results: Increasing annual NG/CT screening among sexually active MSM by 60% averted 4.7% of HIV infections over a 10-year period (interquartile range (IQR): 2.3, 7.3). More HIV infections were averted when screening was focused on MSM with multiple recent sex partners: 60% coverage among MSM with multiple recent sex partners averted 9.8% of HIV infections (IQR: 8.1, 11.6). Increased STI screening among MSM without HIV averted more new HIV infections compared to the transmissions averted due to screening MSM with HIV, but fewer NG/CT tests were needed among MSM with HIV to avert a single new HIV infection. Conclusions: NG/CT screening among MSM is expected to lead to modest but clinically relevant reductions in HIV incidence among MSM.

AU The:severity Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly of infectious disease outbreaks is governed by:patterns of human contact, which vary by geography, social organization, mobility, access to technology and healthcare, economic development, and culture. Whereas globalized societies and urban centers exhibit characteristics that can heighten vulnerability to pandemics, small-scale subsistence societies occupying remote, rural areas may be buffered. Accordingly, voluntary collective isolation has been proposed as one strategy to mitigate the impacts of COVID-19 and other pandemics on small-scale Indigenous populations with minimal access to healthcare infrastructure. To assess the vulnerability of such populations and the viability of interventions such as voluntary collective isolation, we simulate and analyze the dynamics of SARS-CoV-2 infection among Amazonian forager-horticulturalists in Bolivia using a stochastic network metapopulation model parameterized with high-resolution empirical data on population structure, mobility, and contact networks. Our model suggests that relative isolation offers little protection at the population level (expected approximatelyAU 80%: PleasenotethatasperPLOSstyle cumulative incidence), ; dono and more remote communities are not conferred protection via greater distance from outside sources of infection, due to common features of small-scale societies that promote rapid disease transmission such as high rates of travel and dense social networks. Neighborhood density, central household location in villages, and household size greatly increase the individual risk of infection. Simulated interventions further demonstrate that without implausibly high levels of centralized control, collective isolation is unlikely to be effective, especially if it is difficult to restrict visitation between communities as well as travel to outside areas. Finally, comparison of model results to empirical COVID-19 outcomes measured via seroassay suggest that our theoretical model is successful at predicting outbreak severity at both the population and community levels. Taken together, these findings suggest that the social organization and relative isolation from urban centers of many rural Indigenous communities offer little protection from pandemics and that standard control measures, including vaccination, are required to counteract effects of tight-knit social structures characteristic of small-scale populations.

BACKGROUND: Mandatory vaccination has been effective in maintaining high vaccination coverage in countries such as the United States. However, there are no peer-reviewed analyses of the association between mandates and both coverage and subsequent incidence of vaccinepreventable disease in Europe. METHODS: Using data from the European Centre for Disease Prevention and Control and the World Health Organization, we evaluated the relationship between country-level mandatory vaccination policies and (1) measles and pertussis vaccine coverage and (2) the annual incidence of these diseases in 29 European countries. Multivariate negative binomial and linear regression models were used to quantify these associations. RESULTS: Mandatory vaccination was associated with a 3.71 (95% confidence interval [CI]: 1.68 to 5.74) percentage point higher prevalence of measles vaccination and a 2.14 (95% CI: 0.13 to 4.15) percentage point higher prevalence of pertussis vaccination when compared with countries that did not have mandatory vaccination. Mandatory vaccination was only associated with decreased measles incidence for countries without nonmedical exemptions (adjusted incidence rate ratio = 0.14; 95% CI: 0.05 to 0.36). We did not find a significant association between mandatory vaccination and pertussis incidence. CONCLUSIONS: Mandatory vaccination and the magnitude of fines were associated with higher vaccination coverage. Moreover, mandatory vaccination was associated with lower measles incidence for countries with mandatory vaccination without nonmedical exemptions. These findings can inform legislative policies aimed at increasing vaccination coverage.

Annual HIV testing is recommended for high-risk populations in the United States, to identify HIV infections early and provide timely linkage to treatment. However, heterosexuals at high risk for HIV, due to their residence in urban areas of high poverty and elevated HIV prevalence, test for HIV less frequently than other risk groups, and late diagnosis of HIV is common. Yet the factors impeding HIV testing in this group, which is predominantly African American/Black and Latino/Hispanic, are poorly understood. The present study addresses this gap. Using a systematic community-based sampling method, venue-based sampling (VBS), we estimate rates of lifetime and recent (past year) HIV testing among high-risk heterosexuals (HRH), and explore a set of putative multi-level barriers to and facilitators of recent testing, by gender. Participants were 338 HRH African American/Black and Latino/Hispanic adults recruited using VBS, who completed a computerized structured assessment battery guided by the Theory of Triadic Influence, comprised of reliable/valid measures on socio-demographic characteristics, HIV testing history, and multi-level barriers to HIV testing. Logistic regression analysis was used to identify factors associated with HIV testing within the past year. Most HRH had tested at least once (94%), and more than half had tested within the past year (58%), but only 37% tested annually. In both men and women, the odds of recent testing were similar and associated with structural factors (better access to testing) and sexually transmitted infection (STI) testing and diagnosis. Thus VBS identified serious gaps in rates of annual HIV testing among HRH. Improvements in access to high-quality HIV testing and leveraging of STI testing are needed to increase the proportion of HRH testing annually for HIV. Such improvements could increase early detection of HIV, improve the long-term health of individuals, and reduce HIV transmission by increasing rates of viral suppression.

Background: Delay discounting has been found to be associated with numerous health-related outcomes, including risky sexual behaviour. To date, it is unclear whether delay discounting measured in different domains is associated within individuals. The goal of this study was to assess the concordance of monetary and sexual delay discounting in men who have sex with men. Methods: Participants completed an online survey, including the Monetary Choice Questionnaire and the Sexual Discounting Task. Linear regression models were used to assess the association between monetary and sexual discount rates. Results: Sexual discount rates did not predict monetary discount rates. There was a substantial amount of clustering of sexual discount rates, requiring sexual discounting data to be categorised. Conclusions: Monetary and sexual delay discounting are distinct processes that are not necessarily associated within individuals, and monetary delay discounting is not an appropriate proxy measure for sexual impulsivity. Data from the Sexual Discounting Task are typically rank-transformed for analysis. These data suggest that this might be an invalid method of analysis. Future studies should investigate the distribution of their data to determine if it is appropriate to analyse sexual discounting data as a continuous measure.