The extraordinary scale-up of antiretroviral therapy (ART) is expected to reduce the rate of new HIV infections at the population level. In this study, we calculated the incidence of HIV for males and females using data from a complete South African population.
The Africa Health Research Institute (AHRI) maintains an annual HIV surveillance system in the Umkhanyakude district of the KwaZulu-Natal province. Between 2004 and 2015, we followed 6,287 males (aged 15–54 years) and 8,661 females (aged 15–49 years) from their earliest HIV-negative test date until their latest HIV-negative or earliest HIV-positive test date. In addition, we obtained viral load measurements from all HIV-positive participants in 2011, 2012, and 2014 and included ART initiation data from the 17 health-care clinics in the AHRI surveillance area.
The HIV incidence rate declined among males aged 15–25 years between 2012 and 2015, from 1.70 (95% CI: 1.13–2.26) to 0.60 (95% CI: 0.00–1.29) events/100 person-years, as well as for males aged 25–54 years, from 3.28 (95% CI: 1.97–4.55) to 1.87 (95% CI: 0.60–3.56) events/100 person-years. For females aged 15–25 years, however, the HIV incidence rate increased from 6.32 (95% CI: 5.34–7.32) to 6.67 (95% CI: 5.25–8.16) events/100 person-years between 2013 and 2015. Throughout the study period, the HIV incidence rate was flat for females aged 25–49 years, ranging from 4.14 (95% CI: 3.35–5.01) to 5.00 (95% CI: 4.37–5.69) events/100 person-years. ART coverage was significantly higher in woman, increasing from 28.3% to 43.6% between 2010 and 2013, when compared with men, which increased from 26.7% to 32.3%. Among woman aged 15–25 years, the virologic suppression level increased from 20.8% (95% CI: 16.5–25.2%) in 2011 to 40% (95% CI: 34.4-45.7%) in 2014. During this period, the virologic suppression level increased only slightly for men of the same age group, from 15.2% (95% CI: 5.8–24.7%) to 18.5% (95% CI: 7.8–29.2%).
The HIV incidence rate declined for all men aged 15–54 years between 2012 and 2015 but increased among young woman aged 15–25 years. We hypothesize that the more conscientious treatment-and-care behaviors of woman -- i.e., higher ART uptake and higher rates of virologic suppression -- has begun to protect men from acquiring HIV.