CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

Methods: The VOICE risk score (5-10, with 10 the highest risk score) is calculated for each woman based on baseline factors including age, marital status, financial stability, STIs, and alcohol usage. Using these data and self-reported sexual behavior not included in the risk score, we developed a Markov chain model of partnership formation, sexual behavior, and HIV transmission and used it to predict HIV incidence in the absence of PrEP. The model is calibrated using reported sexual activity, incidence data from the VOICE trial, and epidemiological data from the 2012 South African National HIV survey. Results: HPTN 082 enrolled 451 African women ages 16-25 with a median VOICE risk score of 7. 15% (68) reported anal sex in the last month, 30%(135) reported multiple partners in the last three months, and 49% (221) had a partner with unknown HIV status. Without PrEP, we predict an HIV incidence of 9.9% (95%CI 8.9-10.9), ranging from 6.3% (5.1-7.8) in women with a risk score of 5 to 21.5% (18.2-24.6) in women with a risk score of 10. Increased incidence at higher risk scores could be due to self-reported differences in sexual behavior. The remaining increase in incidence was attributed by the model to higher partner HIV prevalence. For example, women who did not live with their main partner were more likely to have multiple partners (OR=2.3, 95%CI 1.7-3.4) but also more likely to use a condom (OR=2.2, 95%CI 1.4-3.4). The model inferred a greatly increased HIV prevalence among their partners (OR=6.2, 95%CI 3.1-12.6). Conclusion: HPTN 082 recruited a cohort of young African women who had multiple risk factors and would benefit from PrEP, given the predicted HIV incidence of 9.9%. These predictions will allow us to evaluate the effectiveness of PrEP stratified by VOICE risk score using an objective measure of adherence (tenofovir levels) from HPTN 082.

wider population (excluding current FSW and clients) attributable to onward transmissions from sustained viremia among FSW living with HIV from 2016 onwards. Results: Simulations reproduced the observed range of HIV prevalence and HIV cascade indicators over time, such that by 2016, overall HIV prevalence across epidemic realizations was 18-32% and FSW HIV prevalence was 43-76%. The model reproduced observed ART coverage: 49-90% among reproductive-age women compared with 20-40% among FSW living with HIV; and between 8-25% of FSW living with HIV were virally suppressed. From 2016 onwards, a failure to achieve viral load suppression among FSW could contribute to 7-12%, 26-34%, and 35-46% of cumulative HIV transmissions in the wider population over the subsequent 1, 10, and 20 years (Figure). After adjusting for current proportion of FSWwho are virally suppressed, the tPAF was highest in settings with increasing HIV incidence among FSW; high turn-over in sex work; and larger number of non-paid partnerships among FSW. Conclusion: Across the broadly generalized epidemics of Southern Africa, a failure to prevent HIV among FSW or to meet the treatment needs of FSW living with HIV could contribute to a large proportion of onward transmissions, and undermine existing efforts of achieving local epidemic control.

Poster Abstracts

1086 A MATHEMATICAL MODELING ANALYSIS OF COMBINATION HIV PREVENTION IN ANTENATAL CLINICS Kimberly A. Powers 1 , Kate Orroth 1 , Nora E. Rosenberg 1 , Lauren A. Graybill 1 , Andrew Kumwenda 2 , Tiwonge Mtande 3 , Katie Mollan 1 , Oliver Mweemba 2 , Wilbroad Mutale 2 , Benjamin H. Chi 1 1 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, 2 University of Zambia, Lusaka, Zambia, 3 University of North Carolina Project–Malawi, Lilongwe, Malawi Background: Given high HIV acquisition risk and increased healthcare engagement during pregnancy, antenatal clinic (ANC) settings in sub-Saharan Africa present major opportunities for HIV prevention. Despite demonstrated success in reducing mother-to-child HIV transmission, few ANC-based programs have considered interventions to prevent horizontal HIV transmission and acquisition among pregnant women and their sexual partners. We hypothesized that combination HIV prevention strategies anchored in ANC settings could

1085 ESTIMATING HIV INCIDENCE AMONG YOUNG WOMEN IN HPTN 082 USING BASELINE HIV RISK SCORES James R. Moore 1 , Deborah J. Donnell 1 , Marie-Claude Boily 2 , Kate M. Mitchell 2 , Sinead Delany-Moretlwe 3 , Connie L. Celum 4 , Dobromir Dimitrov 1 1 Fred Hutchinson Cancer Research Center, Seattle, WA, USA, 2 Imperial College London, London, UK, 3 Wits Reproductive Health and HIV Institute, Johannesburg, South Africa, 4 University of Washington, Seattle, WA, USA Background: Pre-exposure prophylaxis (PrEP) is highly efficacious for prevention of HIV acquisition, but adherence to PrEP remains a major barrier. HPTN 082 is testing strategies to support PrEP adherence in young African women. A mathematical modelling approach is used to predict HIV incidence in the absence of PrEP among HPTN 082 participants, using the previously validated VOICE risk score and baseline sexual activity data from HPTN 082. This predicted incidence will provide a counterfactual to estimate PrEP effectiveness in this population.

CROI 2019 427