Background International and global organisations advocate targeting interventions to areas of high HIV prevalence (ie, hotspots). To better understand the potential benefits of geo-targeted control, we assessed the extent to which HIV hotspots along Lake Victoria sustain transmission in neighbouring populations in south-central Uganda. Methods We did a population-based survey in Rakai, Uganda, using data from the Rakai Community Cohort Study. The study surveyed all individuals aged 15-49 years in four high-prevalence Lake Victoria fishing communities and 36 neighbouring inland communities. Viral RNA was deep sequenced from participants infected with HIV who were antiretroviral therapy-naive during the observation period. Phylogenetic analysis was used to infer partial HIV transmission networks, including direction of transmission. Reconstructed networks were interpreted through data for current residence and migration history. HIV transmission flows within and between high-prevalence and low-prevalence areas were quantified adjusting for incomplete sampling of the population. Findings Between Aug 10, 2011, and Jan 30, 2015, data were collected for the Rakai Community Cohort Study. 25 882 individuals participated, including an estimated 75•7% of the lakeside population and 16•2% of the inland population in the Rakai region of Uganda. 5142 participants were HIV-positive (2703 [13•7%] in inland and 2439 [40•1%] in fishing communities). 3878 (75•4%) people who were HIV-positive did not report antiretroviral therapy use, of whom 2652 (68•4%) had virus deep-sequenced at sufficient quality for phylogenetic analysis. 446 transmission networks were reconstructed, including 293 linked pairs with inferred direction of transmission. Adjusting for incomplete sampling, an estimated 5•7% (95% credibility interval 4•4-7•3) of transmissions occurred within lakeside areas, 89•2% (86•0-91•8) within inland areas, 1•3% (0•6-2•6) from lakeside to inland areas, and 3•7% (2•3-5•8) from inland to lakeside areas. Interpretation Cross-community HIV transmissions between Lake Victoria hotspots and surrounding inland populations are infrequent and when they occur, virus more commonly flows into rather than out of hotspots. This result suggests that targeted interventions to these hotspots will not alone control the epidemic in inland populations, where most transmissions occur. Thus, geographical targeting of high prevalence areas might not be effective for broader epidemic control depending on underlying epidemic dynamics.
Introduction
Pre‐exposure prophylaxis (PrEP) programmes have been initiated in sub‐Saharan Africa to prevent HIV acquisition in key populations at increased risk. However, data on PrEP uptake and retention in high‐risk African communities are limited. We evaluated PrEP uptake and retention in HIV hyperendemic fishing villages and trading centres in south‐central Uganda between April 2018 and March 2019.
Methods
PrEP eligibility was assessed using a national risk screening tool. Programme data were used to evaluate uptake and retention over 12 months. Multivariable modified Poisson regression estimated adjusted prevalence ratios (aPR) and 95% Confidence intervals (CIs) of uptake associated with covariates. We used Kaplan–Meier analysis to estimate retention and multivariable Cox regression to estimate adjusted relative hazards (aRH) and 95% CIs of discontinuation associated with covariates.
Results and discussion
Of the 2985 HIV‐negative individuals screened; 2750 (92.1 %) were eligible; of whom 2,536 (92.2%) accepted PrEP. Male (aPR = 0.91, 95% CI = 0.85 to 0.97) and female (aPR = 0.85, 95% CI = 0.77 to 0.94) fisher folk were less likely to accept compared to HIV‐discordant couples. Median retention was 45.4 days for both men and women, whereas retention was higher among women (log rank, p < 0.001) overall. PrEP discontinuation was higher among female sex workers (aRH = 1.42, 95% CI = 1.09 to 1.83) and female fisher folk (aRH = 1.99, 95% CI = 1.46 to 2.72), compared to women in discordant couples. Male fisher folk (aRH = 1.37, 95% CI = 1.07 to 1.76) and male truck drivers (aRH = 1.49, 95% CI = 1.14 to 1.94) were more likely to discontinue compared to men in discordant couples. Women 30 to 34 years tended to have lower discontinuation rates compared to adolescents 15 to 19 years (RH = 0.78 [95% CI = 0.63 to 0.96]).
Conclusions
PrEP uptake was high, but retention was very low especially among those at the highest risk of HIV: fisher folk, sex workers and truck drivers and adolescent girls. Research on reasons for PrEP discontinuation could help optimize retention.
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