Background: Reducing new HIV infections among adolescents and young adults is a major focus of HIV prevention investments including the PEPFAR-supported DREAMS initiative. We aim to characterize recent trends in sexual behaviour and knowledge of HIV in a setting designated for DREAMS investments.
Methods: A general population cohort in a high-prevalence setting in rural KwaZulu-Natal, South Africa were surveyed annually. Between 2005 and 2015, 28,239 individuals aged 16-24 years (14,654 women; 13,585 men) participated in sexual behaviour or HIV testing surveys (68,920 observations).
Results: The proportion of youth reporting being sexually active and reports of multiple partnerships in the past year have declined (time trend p< 0.001 for all outcomes, Figure 1). Reported condom use at last sex with any partner increased over time but much more slowly among women than men. HIV prevalence has increased among both sexes. Knowledge of HIV status was higher with older ages and has reduced slightly after peaking around 2012. Knowledge of where to obtain ART is nearly universal. Support for the observed trends in self-reported sexual activity will be explored by examining fertility data.
Conclusions: Reports of sexual activity and multiple partnerships among adolescents have declined in recent years. HIV prevalence increases may be a combination of ongoing high infection risk and survival of children on ART into young-adulthood. Results suggest that substantial scope remains for increasing HIV testing and consistent condom use particularly among young women.

Trends in sexual behaviour, HIV prevalence, and knowledge of HIV 2005-2015 (all values proportions)
[Trends in sexual behaviour, HIV prevalence, and knowledge of HIV 2005-2015 (all values proportions)]