High coverage of ART associated with decline in risk of HIV acquisition in rural KwaZulu-Natal, South Africa

Abstract

The landmark HIV Prevention Trials Network (HPTN) 052 trial in HIV-discordant couples demonstrated unequivocally that treatment with antiretroviral therapy (ART) substantially lowers the probability of HIV transmission to the HIV-uninfected partner. However, it has been vigorously debated whether substantial population-level reductions in the rate of new HIV infections could be achieved in "real-world" sub-Saharan African settings where stable, cohabiting couples are often not the norm and where considerable operational challenges exist to the successful and sustainable delivery of treatment and care to large numbers of patients. We used data from one of Africa's largest population-based prospective cohort studies (in rural KwaZulu-Natal, South Africa) to follow up a total of 16,667 individuals who were HIV-uninfected at baseline, observing individual HIV seroconversions over the period 2004 to 2011. Holding other key HIV risk factors constant, individual HIV acquisition risk declined significantly with increasing ART coverage in the surrounding local community. For example, an HIV-uninfected individual living in a community with high ART coverage (30 to 40% of all HIV-infected individuals on ART) was 38% less likely to acquire HIV than someone living in a community where ART coverage was low (<10% of all HIV-infected individuals on ART).

Fig. 1

Time series of maps showing the evolution of the proportion of the HIV-infected adults (≥15 years of age) receiving ART (A) and HIV prevalence (B) across the demographic surveillance area (2005 to 2008, left to right, top row; 2009 to 2011, left to right, bottom row). A, Africa Centre; B, Mtubatuba Town; C, KwaMsane Township. Main roads are also superimposed for ease of reference. Each pixel on the map corresponds to the proportion of the total HIV-infected population receiving ART (A) and total population infected with HIV (B) in the surrounding local community as measured using a standard Gaussian kernel of radius 3 km. Over the study period, estimated HIV prevalence in the adult population (≥15 years of age) increased from 18 to 24%, which is likely a consequence of the increasing life span of HIV-infected people due to ART. The proportion of the total HIV-infected population receiving ART was estimated at 37% in mid-2011.

Fig. 2

Female (A) and male (B) age variations in HIV incidence (95% CI) by 5-year age-group for entire sample of repeat testers (N = 16,667; 53,605 person years of observation). Superimposed on the graphs are log-normal functions (obtained by maximum likelihood) fitted to the incidence point estimates.

Fig. 3

Results of the multivariable analysis showing an HIV-uninfected individual’s HIV aHR (95% CI) and associated P values for different categories of ART coverage, that is, the proportion of the total HIV infected population receiving ART (A and B), and HIV prevalence (C) in the surrounding local community (derived using a standard Gaussian kernel of radius 3 km, as shown in Fig. 1, A and B). (A) displays the aHRs adjusted for systematic differences in age and sex, and (B) and (C) display the aHRs adjusted for all other variables in the final model (see Table 1 and table S2 multivariable analysis).