CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

for men. Our network analysis shows that individuals in communities where prevalence is high travel to areas where prevalence is low, and vice versa. We estimate that 60% of the overall risk of acquiring HIV in Namibia is localized, 17% is due to visitors, and 23% is due to travel; notably, 40% of the overall risk is related to mobility. Mobility is more important in some areas than others: it contributes to more than half of the overall risk for women in ~20% of constituencies, and for men in ~10%. Using our epidemic-mobility network and risk metrics, we identify which areas of the country are the most vulnerable to the importation of risk, and which are the most important in disseminating risk. Conclusion: The HIV epidemic in Namibia is not simply driven by localized transmission; a high level of mobility has created a dynamic, widely dispersed risk network. Our results imply that it may be harder to eliminate HIV in Namibia than currently appears.

(-6.1 pp; 95 %CI: -8.8, -3.4). However, spatio-temporal analysis revealed heterogeneity in MTCT trends at various geographic levels. Within catchment areas, MTCT persistently decreased in 44 (31.7%) CAs, however 17 (12.2%) CAs had persistent increases in MTCT and 78 (56.1%) CAs had no change or inconsistent direction of change. By province, the proportion of CAs with increased MTCT was greatest in Harare (3/8, 37.5%) and lowest in Mashonaland Central (2/30, 6.7%) and Manicaland (4/52, 7.7%). Within-province variation was also apparent, for example with clusters of CAs with increasing MTCT evident within provinces such as Manicaland where proportionally few CAs had increasing MTCT (Figure). Conclusion: While overall trends in MTCT showmarked progress toward elimination in Zimbabwe, variability by health facility catchment area supports the need for differentiated strategies at the sub-national level. Spatial analysis provides a useful tool to identify high priority areas for targeted and efficient allocation of PMTCT services.

Poster Abstracts

875 MAPPING OF HIV-1C TRANSMISSION NETWORKS IN BOTSWANA

Vlad Novitsky 1 , Melissa Zahralban-Steele 1 , Sikhulile Moyo 2 , Tapiwa Nkhisang 1 , Dorcas Maruapula 2 , Mary F. McLane 1 , Jean Leidner 3 , Kara Bennett 4 , Tendani Gaolathe 2 , Etienne Kadima 2 , Shahin Lockman 2 , Joseph Makhema 2 , Simani Gaseitsiwe 2 , Victor De Gruttola 1 , Max Essex 1 1 Harvard University, Boston, MA, USA, 2 Botswana Harvard AIDS Institute Partnership, Gabarone, Botswana, 3 Goodtables Data Consulting, Norman, OK, USA, 4 Bennett Statistical Consulting, Inc, New York, NY, USA Background: Better understanding of HIV transmission networks and their dynamics could help to prevent new viral transmissions and ultimately curtail HIV spread. Phylogenetic mapping of HIV transmission networks is a promising approach in this process. Methods: Using proviral DNA and/or viral RNA as a template for amplification, we obtained near full-length HIV-1C sequences from 5,182 HIV-infected individuals participating in four studies in Botswana from 1996–2018, including 4,473 (86%; 72% on ART) sequences from the Botswana Combination Prevention Project (BCPP) sampled 2013–2018. In addition, 444 non-Botswana sequences were included in analyses. Phylogenetic relationships among viral sequences were estimated by maximum likelihood using RAxML v.8 and the GTR+Γ4+Ι model. Genotyping density was defined as a proportion of genotyped cases among the estimated total number of HIV-infected community residents. We defined a cluster as a phylogenetically distinct viral lineage that gives rise to a monophyletic subtree of the overall phylogeny with bootstrap support of splits ≥0.80 and median pairwise distance <10th quantile of the overall distribution of pairwise distances in the analyzed set of near full-length genome sequences. Results: We identified 781 phylogenetically distinct HIV-1C lineages circulating in Botswana by mid-2018, including 726 (93%) clusters with Botswana participants. The cluster size varied from 2 to 20 members per cluster. The

874 SPATIAL ANALYSIS TO IDENTIFY EMERGING HOT SPOTS OF MTCT IN ZIMBABWE, 2012-2018 Carolyn A. Fahey 1 , Sandra I. McCoy 1 , Aybuke Koyuncu 1 , Mi-Suk Kang Dufour 2 , Angela Mushavi 3 , Agnes Mahomva 4 , Nancy Padian 1 , Frances Cowan 5 1 University of California Berkeley, Berkeley, CA, USA, 2 University of California San Francisco, San Francisco, CA, USA, 3 Ministry of Health and Child Welfare, Harare, Zimbabwe, 4 Elizabeth Glaser Pediatric AIDS Foundation, Washington, DC, USA, 5 Centre for Sexual Health and HIV/AIDS Research Zimbabwe, Harare, Zimbabwe Background: To inform targeting of services for the elimination of mother- to-child HIV transmission (MTCT) in Zimbabwe, we examined spatio-temporal trends in MTCT from 2012 to 2018. Methods: We conducted three serial cross-sectional serosurveys of infants (9-18 months old) and their mothers or caregivers (≥16 years old) to assess MTCT and related outcomes. Using a multi-stage sampling strategy, in five of ten provinces we randomly selected 157 of 699 health facilities offering prevention of MTCT (PMTCT) services. Within the catchment area (CA) of each facility, we enumerated infants born 9-18 months prior (alive or deceased) and selected a random sample. A total of 26,882 mother- or caregiver-infant pairs were interviewed and tested for HIV in 2012 (n=8,800), 2014 (n=10,404) and 2018 (n=7,678). Global Positioning System (GPS) coordinates were also collected for each facility. We calculated the MTCT rate for the 139 CAs which were included in all three waves and assessed overall temporal changes using a population- averaged model. We then classified changes in MTCT by CA as persistently decreasing (downward trend between each consecutive wave), persistently increasing, or no change/inconsistent direction and assessed spatial trends to identify emerging “hot spots” and diminishing “cold spots”. Results: Overall, catchment area MTCT declined from 9.7% (2012) to 5.1% in 2014 [-4.5 percentage points (pp); 95% CI: -7.2, -1.9] and to 3.6% in 2018

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