No abstract

Introduction Randomized clinical trials have demonstrated the efficacy of antiretroviral pre‐exposure prophylaxis (Pr EP ) in preventing HIV acquisition among men who have sex with men ( MSM ). However, limited research has examined initiation and adherence to Pr EP among Black MSM ( BMSM ) in the United States ( US ) who are disproportionately represented among newly HIV infected and late to care individuals. This research reports on the HIV Prevention Trials Network 073 ( HPTN 073) study aimed to examine Pr EP initiation, utilization and adherence among Black MSM utilizing the theoretically principled, culturally informed and client‐centered care coordination (C4) model. Methods The HPTN 073 study enrolled and followed 226 HIV ‐uninfected Black MSM in three US cities (Los Angeles, CA ; Washington DC ; and Chapel Hill, NC ) from February 2013 through September 2015. Study participants were offered once daily oral emtricitabine/tenofovir ( FTC / TDF ) Pr EP combined with C4 and followed up for 52 weeks. Participants received HIV testing, risk reduction education and clinical monitoring. Results Of the 226 men enrolled, 178 participants initiated Pr EP (79%), and of these 64% demonstrated Pr EP utilization at week 26 (mid‐point of the study) based on pharmacokinetic testing. Condomless anal sex with an HIV ‐infected or unknown status casual male partner was statistically significantly associated with a greater likelihood of Pr EP initiation (adjusted odds ratio ( OR ) 4.4, 95% confidence interval ( CI ) 1.7, 11.7). Greater age (≥25 vs. <25, OR 2.95, 95% CI 1.37 –6.37), perception of having enough money ( OR 3.6, 95% CI 1.7 to 7.7) and knowledge of male partner taking Pr EP before sex ( OR 2.22, 95% CI 1.03 to 4.79) were statistically significantly associated with increased likelihood of Pr EP adherence at week 26. Annualized HIV incidence was 2.9 (95% CI 1.2 to 7.9) among those who init...

Women at high-risk for HIV acquisition often face challenges that hinder their retention in HIV prevention trials. These same challenges may contribute to missed clinical care visits among HIV-infected women. This article, informed by the Gelberg-Andersen Behavioral Model for Vulnerable Populations, identifies factors associated with missed study visits and describes the multifaceted retention strategies used by study sites. HPTN 064 was a multisite, longitudinal HIV seroincidence study in 10 US communities. Eligible women were aged 18-44 years, resided in a census tract/zipcode with high poverty and HIV prevalence, and self-reported ≥1 personal or sex partner behavior related to HIV acquisition. Multivariate analyses of predisposing (e.g., substance use) and enabling (e.g., unmet health care needs) characteristics, and study attributes (i.e., recruitment venue, time of enrollment) identified factors associated with missed study visits. Retention strategies included: community engagement; interpersonal relationship building; reduction of external barriers; staff capacity building; and external tracing. Visit completion was 93% and 94% at 6 and 12 months. Unstable housing and later date of enrollment were associated with increased likelihood of missed study visits. Black race, recruitment from an outdoor venue, and financial responsibility for children were associated with greater likelihood of attendance. Multifaceted retention strategies may reduce missed study visits. Knowledge of factors associated with missed visits may help to focus efforts.

Longstanding social and economic inequities elevate health risks and vulnerabilities for Black, Indigenous and People of Color (BIPOC) communities. Engagement of BIPOC communities in infectious disease research is a critical component in efforts to increase vaccine confidence, acceptability, and uptake of future approved products. Recent data highlight the relative absence of BIPOC communities in vaccine clinical trials. Intentional and effective community engagement methods are needed to improve BIPOC inclusion. We describe the methods utilized for the successful enrollment of BIPOC participants in the U.S. Government (USG)-funded COVID-19 Prevention Network (CoVPN)-sponsored vaccine efficacy trials and analyze the demographic and enrollment data across the efficacy trials to inform future efforts to ensure inclusive participation. Across the four USG-funded COVID-19 vaccine clinical trials for which data are available, 47% of participants enrolled at CoVPN sites in the US were BIPOC. White enrollment outpaced enrollment of BIPOC participants throughout the accrual period, requiring the implementation of strategies to increase diverse and inclusive enrollment. Trials opening later benefitted considerably from strengthened community engagement efforts, and greater and more diverse volunteer registry records. Despite robust fiscal resources and a longstanding collaborative and collective effort, enrollment of White persons outpaced that of BIPOC communities. With appropriate resources, commitment and community engagement expertise, the equitable enrollment of BIPOC individuals can be achieved. To ensure this goal, intentional efforts are needed, including an emphasis on diversity of enrollment in clinical trials, establishment of enrollment goals, ongoing robust community engagement, conducting population-specific trials, and research to inform best practices.

Analytical expressions are found for the derivatives of commonly used Mie scattering parameters, in particular the absorption and the scattering efficiencies, and for the angular intensity functions. These expressions are based on the analytical derivatives of the Mie scattering amplitudes a(n) and b(n) with respect to the particle size parameter and complex refractive index. In addition, analytical derivatives are found for the volume absorption and scattering coefficients, as well as for the intensity functions of a population of particles with log normal size distribution. These derivatives are given with respect to the total number density, to the median radius and spread of the distribution, and to the refractive index. Comparison between analytically and numerically computed derivatives showed the analytical version to be 2.5 to 6.5 times as fast for the single-particle and particle-distribution cases, respectively.