Changing dynamics of HIV transmission in Côte d'Ivoire: modeling which key populations acquired and transmitted infections and estimating the impact of past HIV interventions (1976-2015)

摘要

Introduction: Understanding the impact of past interventions and how it affected transmission dynamics is key to guiding prevention efforts. We e stimated the population-level impact of condom, antiretroviral therapy (ART), and preventio n of mother-to-child transmission activities on HIV transmission and the contribution of key ris k factors on HIV acquisition and transmission. Methods: An age stratified dynamical model of sexual and ve rtical HIV transmission among the general population, female sex workers (FSW), and m en who have sex with men (MSM) was calibrated to detailed prevalence and intervention data. We estimated the fraction of HIV infections averted by the interventions, and the fr action of incident infections acquired and transmitted by different populations over successiv e 10-year periods (1976-2015). Results: Overall, condom use averted 61% (95% Credible Inte rvals: 56-66%) of all adult infections during 1987-2015 mainly due to increases by FSW (46% of infections averted). In comparison, ART prevented 15% (10-19%) of adult inf ections during 2010- 2015. As a result, FSW initially (1976-1985) contributed 95% (91-97%) of all new infections, declining to 19% (11-27%) during 2005-2015. Older men and clients mi xing with non-FSW are currently the highest contributor to transmission. MSM contribute d ≤ 4% transmissions throughout. Young women (15-24 years; excluding FSW) do not transmit more infection than they acquired. Conclusion: Early increases in condom use, mainly by FSW, have substantially reduced HIV transmission. Clients of FSW and older men have bec ome the main source of transmission whereas young women remain at increased risk. Stren gthening prevention and scaling-up of ART, particularly to FSW and CFSW, is important.