CROI 2020 Abstract eBook

Abstract eBook

Poster Abstracts

generalized epidemic into eight loosely connected sub-epidemics. This suggests that interventions may be the most effective if they are implemented at the level of the MC. Furthermore, it may be very difficult to reduce incidence in Windhoek and Oshakati, as they are connected (by travel) to multiple other sub-epidemics.

925 MAPPING AND CHARACTERISING HIV TRANSMISSION HOTSPOTS IN SUB- SAHARAN AFRICA Caroline Bulstra 1 , Jan A. Hontelez 2 , Federica Giardina 2 , Richard Steen 2 , Nico Nagelkerke 2 , Till Bärnighausen 3 , Sake de Vlas 2 1 Heidelberg University, Heidelberg, Germany, 2 Erasmus University Medical Center, Rotterdam, Netherlands, 3 Africa Health Research Institute, Mtubatuba, South Africa Background: In the generalised epidemics of sub-Saharan Africa (SSA), HIV prevalence shows patterns of clustered micro-epidemics. We mapped and characterised these so-called ‘hotspots’ for young adults (15-29 years of age), as a proxy for transmission hotspots, for seven countries in Eastern and Southern Africa: Kenya, Malawi, Mozambique, Tanzania, Uganda, Zambia, and Zimbabwe. Methods: We used geolocated survey data from the most recent USAID Demographic and Health Surveys and AIDS Indicator Surveys, which included 53,234 young adults from 3,665 sample locations. Ordinary kriging was applied to predict HIV prevalence at unmeasured locations. We explored to what extent behavioural, socioeconomic and environmental factors explain HIV prevalence at the individual- and sample location-level, by developing a series of multilevel multivariable logistic regression models. We then compared and geospatially visualised how heterogeneity and hotspots can be explained by the models, using the sample location random effect estimates from each model. Results: We found substantial HIV prevalence heterogeneity among both adults (Figure 1A) and young adults (Figure 1B) througout all countries, with clear geospatial hotspots among young adults characterised by areas with prevalences of over 11% or 15% alternating with areas of prevalences between 0% and 2%. The heterogeneity in young adults could be explained for 15.6% by an interplay of known behavioural, socioeconomic and environmental factors. Maps of the interpolated random effect estimates show that environmental variables, representing indicators of economic activity, were most powerful in explaining HIV hotspot locations. Conclusion: In young adults, micro-epidemics of relatively high HIV prevalence alternate with areas of very low prevalence, clearly illustrating the existence of transmission hotspots. These hotspots are partially characterised by high economic activity, relatively high socioeconomic status, and risky sexual behaviour. Localised HIV prevention interventions specifically tailored to the populations at risk will be essential to curb transmission. More fine-scale geospatial mapping of key populations, such as sex workers, and migrant populations, could help to further understand the drivers of these transmission hotspots, and to determine to what extent they fuel the generalised epidemics in SSA.

Poster Abstracts

924 LOCAL AND REGIONAL DYNAMICS OF HIV EPIDEMICS AMONG HIGH-RISK POPULATIONS IN HAITI Frantz Jean-Louis 1 , Jean Wysler Domercant 2 , Caroline Ignacio 3 , Sara Gianella 3 , Guethina Galbaud 1 , Davey M. Smith 3 , Antoine Chaillon 3 1 Equip-MatCH, Petion-Ville, Haiti, 2 Wits Health Consortium, Johannesburg, South Africa, 3 University of California San Diego, San Diego, CA, USA Background: Although the overall HIV prevalence in Haiti has been stable around 2% for the past 15 years, the prevalence in high risk groups, such as men having sex with men (MSM) and female sex workers (FSW), are much higher, 12.9% and 8.7% respectively. To characterize the HIV epidemics in the Caribbean, we explored: (1) the dynamics of HIV transmission among persons with HIV (PWH) from high risk groups in Haiti, and (2) viral dispersal across the Caribbean. Methods: 78 HIV-1 pol sequences were newly sampled and analyzed from MSM, FSW and sexual partners of FSW from Haiti. We also analyzed 3,908 publicly available HIV-1 pol sequences from the Caribbean and 33,100 from the rest of the world. Phylogenetic and network analyses were performed to infer local HIV transmission in Haiti. Sequences were screened for drug resistant mutations (DRM). Next, we applied a multistep phylogenetic approach to evaluate dispersal across the Caribbean: (1) identify all well-supported monophyletic clades; (2) all clades of size ≥ 3 identified were used to perform a discrete phylogeographic inference to evaluate the dispersal history across Caribbean countries; (3) we applied a generalized linear model (GLM) to test the association of epidemiologic factors and connectivity (i.e. geographic distances and air traffic passenger flow) with lineage dispersal. Results: We first evaluated HIV transmission dynamics within Haiti: Genetic network analyses found that 23% (18/78) had a putative linkage with ≥1 sequence forming 6 clusters (size: 2-5 PWH), Fig.A. Clustering Haitian PWH were mostly MSM (10/18) or FSW clients (5/18). Considering DRM, K103N or M184V were shared in 83.3% clusters. Next, we evaluated geospatial dynamics in the Caribbean’s: Discrete phylogeographic analysis revealed viral trafficking from the Dominican Republic (DR) toward Haiti but also from Puerto Rico (PR) and Trinidad and Tobago toward DR and PR respectively (Fig.B). As might be expected, the GLM analysis showed that closer countries were the most likely to show viral exchange. Conclusion: HIV transmissions occurs across risk groups in Haiti with high rates of shared DRMs. This study also found that local epidemics are likely sustained by regional human migration. Thus, prevention efforts to curb local epidemics will need to consider all risk groups and also epidemics from other countries.

CROI 2020 347