New insights into HIV epidemic in South Africa: key findings from the National HIV Prevalence, Incidence and Behaviour Survey, 2012.

This article presents key findings from the 2012 HIV prevalence, incidence and behaviour survey conducted in South Africa and explores trends in the HIV epidemic. A representative household based survey collected behavioural and biomedical data among people of all ages. Chi-squared test for association and formal trend tests (2002, 2005, 2008 and 2012) were used to test for associations and trends in the HIV epidemic across the four surveys. In 2012 a total of 38 431 respondents were interviewed from 11 079 households; 28 997 (67.5%) of 42 950 eligible individuals provided blood specimens. HIV prevalence was 12.2% [95% CI: 11.4-13.1] in 2012 with prevalence higher among females 14.4% than males 9.9%. Adults aged 25-49 years were most affected, 25.2% [95% CI: 23.2-27.3]. HIV prevalence increased from 10.6% [95%CI: 9.8-11.6] in 2008 to 12.2% [95% CI: 11.4-13.1] in 2012 (p < 0.001). Antiretroviral treatment (ART) exposure doubled from 16.6% in 2008 to 31.2% in 2012 (p < 0.001). HIV incidence in 2012 among persons 2 years and older was 1.07% [95% CI: 0.87-1.27], with the highest incidence among Black African females aged 20-34 years at 4.5%. Sexual debut before 15 years was reported by 10.7% of respondents aged 15-24 years, and was significantly higher among male youth than female (16.7% vs. 5.0% respectively, p < 0.001). Reporting of multiple sexual partners in the previous 12 months increased from 11.5% in 2002 to 18.3% in 2012 (p < 0.001). Condom use at last sex dropped from 45.1% in 2008 to 36.2% in 2012 (p < 0.001). Levels of accurate HIV knowledge about transmission and prevention were low and had decreased between 2008 and 2012 from 31.5% to 26.8%. South Africa is on the right track with scaling up ART. However, there have been worrying increases in most HIV-related risk behaviours. These findings suggest that there is a need to scale up prevention methods that integrate biomedical, behavioural, social and structural prevention interventions to reverse the tide in the fight against HIV.

Age-disparate sex and HIV risk for young women from 2002 to 2012 in South Africa.

INTRODUCTION: Age-disparate sex has long been considered a factor that increases HIV risk for young women in South Africa. However, recent studies from specific regions in South Africa have found conflicting evidence. Few studies have assessed the association between age-disparate partnerships (those involving an age gap of 5 years or more) and HIV risk at the national level. This study investigates the relationship between age-disparate sex and HIV status among young women aged 15-24 in South Africa. METHODS: Nationally representative weighted data from the 2002, 2005, 2008, and 2012 South African National HIV Surveys were analysed for young women aged 15-24 years using bivariate analyses and multiple logistic regressions. RESULTS: After conducting multiple logistic regression analyses and controlling for confounders, young women with age-disparate partners had greater odds of being HIV positive in every survey year: 2002 (aOR = 1.74, 95%CI: 0.81-3.76, p = 0.16); 2005 (aOR = 2.11, 95%CI: 1.22-3.66, p < 0.01); 2008 (aOR = 2.02, 95%CI: 1.24-3.29, p < 0.01); 2012 (aOR = 1.53, 95%CI: 0.92-2.54, p < 0.1). The odds of being HIV positive increased for each year increase in their male partner's age in 2002 (aOR = 1.10, 95%CI: 0.98-1.22, p = 0.11), 2005 (aOR = 1.10, 95%CI: 1.03-1.17, p < 0.01), 2008 (aOR = 1.08, 95%CI: 1.01-1.15, p < 0.05), and 2012 (aOR = 1.08, 95%CI: 1.01-1.16, p < 0.05). Findings were statistically significant (p < 0.1) for the years 2005, 2008, and 2012. CONCLUSION: Our findings suggest that age-disparate sex continues to be a risk factor for young women aged 15-24 in South Africa at a national level. These results may reflect variation in HIV risk at the national level compared to the differing results from recent studies in a demographic surveillance system and trial contexts. In light of recent contradictory study results, further research is required on the relationship between age-disparate sex and HIV for a more nuanced understanding of young women's HIV risk.

Rates of HIV testing and diagnosis in South Africa: successes and challenges.

BACKGROUND: UNAIDS aims for 90% of HIV-positive individuals to be diagnosed by 2020, but few attempts have been made in developing countries to estimate the fraction of the HIV-positive population that has been diagnosed. METHODS: To estimate the rate of HIV diagnosis in South Africa, reported numbers of HIV tests performed in the South African public and private health sectors were aggregated, and estimates of HIV prevalence in individuals tested for HIV were combined. The data were integrated into a mathematical model of the South African HIV epidemic, which was additionally calibrated to estimates of the fraction of the population ever tested for HIV, as reported in three national household surveys. RESULTS: The fraction of HIV-positive adults who were undiagnosed declined from more than 80% in the early 2000s to 23.7% [95% confidence interval (95% CI) 23.1-24.3] in 2012. The undiagnosed proportion in 2012 was substantially higher in men (31.9%, 95% CI 29.7-34.3) than in women (19.0%, 95% CI 17.9-19.9). Projected probabilities of experiencing disease progression (CD4 cell count <350 cells/µl) without diagnosis are more than 50% for most HIV-positive adults over the age of 40. The fraction of HIV-positive adults who are undiagnosed is projected to decline to 8.9% by 2020 if current targets (10 million tests per annum) are met. CONCLUSION: South Africa has made significant progress in expanding access to HIV testing, and at current testing rates, the target of 90% of HIV-positive adults diagnosed by 2020 is likely to be reached. However, uptake is relatively low in men and older adults.

Assessment of epidemic projections using recent HIV survey data in South Africa: a validation analysis of ten mathematical models of HIV epidemiology in the antiretroviral therapy era.

BACKGROUND: Mathematical models are widely used to simulate the effects of interventions to control HIV and to project future epidemiological trends and resource needs. We aimed to validate past model projections against data from a large household survey done in South Africa in 2012. METHODS: We compared ten model projections of HIV prevalence, HIV incidence, and antiretroviral therapy (ART) coverage for South Africa with estimates from national household survey data from 2012. Model projections for 2012 were made before the publication of the 2012 household survey. We compared adult (age 15-49 years) HIV prevalence in 2012, the change in prevalence between 2008 and 2012, and prevalence, incidence, and ART coverage by sex and by age groups between model projections and the 2012 household survey. FINDINGS: All models projected lower prevalence estimates for 2012 than the survey estimate (18·8%), with eight models' central projections being below the survey 95% CI (17·5-20·3). Eight models projected that HIV prevalence would remain unchanged (n=5) or decline (n=3) between 2008 and 2012, whereas prevalence estimates from the household surveys increased from 16·9% in 2008 to 18·8% in 2012 (difference 1·9, 95% CI -0·1 to 3·9). Model projections accurately predicted the 1·6 percentage point prevalence decline (95% CI -0·3 to 3·5) in young adults aged 15-24 years, and the 2·2 percentage point (0·5 to 3·9) increase in those aged 50 years and older. Models accurately represented the number of adults on ART in 2012; six of ten models were within the survey 95% CI of 1·54-2·12 million. However, the differential ART coverage between women and men was not fully captured; all model projections of the sex ratio of women to men on ART were lower than the survey estimate of 2·22 (95% CI 1·73-2·71). INTERPRETATION: Projections for overall declines in HIV epidemics during the ART era might have been optimistic. Future treatment and HIV prevention needs might be greater than previously forecasted. Additional data about service provision for HIV care could help inform more accurate projections. FUNDING: Bill & Melinda Gates Foundation.

Recent HIV prevalence trends among pregnant women and all women in sub-Saharan Africa: implications for HIV estimates.

OBJECTIVES: National population-wide HIV prevalence and incidence trends in sub-Saharan Africa (SSA) are indirectly estimated using HIV prevalence measured among pregnant women attending antenatal clinics (ANC), among other data. We evaluated whether recent HIV prevalence trends among pregnant women are representative of general population trends. DESIGN: Serial population-based household surveys in 13 SSA countries. METHODS: We calculated HIV prevalence trends among all women aged 15-49 years and currently pregnant women between surveys conducted from 2003 to 2008 (period 1) and 2009 to 2012 (period 2). Log-binomial regression was used to test for a difference in prevalence trend between the two groups. Prevalence among pregnant women was age-standardized to represent the age distribution of all women. RESULTS: Pooling data for all countries, HIV prevalence declined among pregnant women from 6.5 [95% confidence interval (CI) 5.3-7.9%] to 5.3% (95% CI 4.2-6.6%) between periods 1 and 2, whereas it remained unchanged among all women at 8.4% (95% CI 8.0-8.9%) in period 1 and 8.3% (95% CI 7.9-8.8%) in period 2. Prevalence declined by 18% (95% CI -9-38%) more in pregnant women than nonpregnant women. Estimates were similar in Western, Eastern, and Southern regions of SSA; none were statistically significant (P>0.05). HIV prevalence decreased significantly among women aged 15-24 years while increasing significantly among women 35-49 years, who represented 29% of women but only 15% of pregnant women. Age-standardization of prevalence in pregnant women did not reconcile the discrepant trends because at older ages prevalence was lower among pregnant women than nonpregnant women. CONCLUSION: As HIV prevalence in SSA has shifted toward older, less-fertile women, HIV prevalence among pregnant women has declined more rapidly than prevalence in women overall. Interpretation of ANC prevalence data to inform national HIV estimates should account for both age-specific fertility patterns and HIV-related sub-fertility.

The effect of changes in condom usage and antiretroviral treatment coverage on human immunodeficiency virus incidence in South Africa: a model-based analysis.

This study aims to assess trends in human immunodeficiency virus (HIV) incidence in South Africa, and to assess the extent to which prevention and treatment programmes have reduced HIV incidence. Two models of the South African HIV epidemic, the STI (sexually transmitted infection)-HIV Interaction model and the ASSA2003 AIDS and Demographic model, were adapted. Both models were fitted to age-specific HIV prevalence data from antenatal clinic surveys and household surveys, using a Bayesian approach. Both models suggest that HIV incidence in 15-49 year olds declined significantly between the start of 2000 and the start of 2008: by 27 per cent (95% CI: 21-32%) in the STI-HIV model and by 31 per cent (95% CI: 23-39%) in the ASSA2003 model, when expressed as a percentage of incidence rates in 2000. By 2008, the percentage reduction in incidence owing to increased condom use was 37 per cent (95% CI: 34-41%) in the STI-HIV model and 23 per cent (95% CI: 14-34%) in the ASSA2003 model. Both models also estimated a small reduction in incidence owing to antiretroviral treatment by 2008. Increased condom use therefore appears to be the most significant factor explaining the recent South African HIV incidence decline.

The contribution of maternal HIV seroconversion during late pregnancy and breastfeeding to mother-to-child transmission of HIV.

BACKGROUND: The prevention of mother-to-child transmission (PMTCT) of HIV has been focused mainly on women who are HIV positive at their first antenatal visit, but there is uncertainty regarding the contribution to overall transmission from mothers who seroconvert after their first antenatal visit and before weaning. METHOD: A mathematical model was developed to simulate changes in mother-to-child transmission of HIV over time, in South Africa. The model allows for changes in infant feeding practices as infants age, temporal changes in the provision of antiretroviral prophylaxis and counseling on infant feeding, as well as temporal changes in maternal HIV prevalence and incidence. RESULTS: The proportion of mother-to-child transmission (MTCT) from mothers who seroconverted after their first antenatal visit was 26% [95% confidence interval (CI): 22% to 30%] in 2008, or 15,000 of 57,000 infections. It is estimated that by 2014, total MTCT will reduce to 39,000 per annum, and transmission from mothers seroconverting after their first antenatal visit will reduce to 13,000 per annum, accounting for 34% (95% CI: 29% to 39%) of MTCT. If maternal HIV incidence during late pregnancy and breastfeeding were reduced by 50% after 2010, and HIV screening were repeated in late pregnancy and at 6-week immunization visits after 2010, the average annual number of MTCT cases over the 2010-2015 period would reduce by 28% (95% CI: 25% to 31%), from 39,000 to 28,000 per annum. CONCLUSION: Maternal seroconversion during late pregnancy and breastfeeding contributes significantly to the pediatric HIV burden and needs greater attention in the planning of prevention of MTCT programs.

The effect of early initiation of antiretroviral treatment in infants on pediatric AIDS mortality in South Africa: a model-based analysis.

BACKGROUND: Guidelines for treatment of pediatric HIV have recently changed to recommend that all infants who are identified as HIV-infected should start antiretroviral treatment (ART) immediately, regardless of their immunologic or clinical status. This study aims to assess the likely impact of this change in guideline in South Africa. METHODS: A mathematical model was developed to simulate mother-to-child transmission of HIV, disease progression, and death of HIV-infected children <15 years of age. The model is calibrated to South African data sources, including prevention of mother-to-child transmission program coverage data, pre-ART survival data, ART program statistics, and pediatric HIV prevalence studies. RESULTS: Relative to what would be expected in the absence of early ART initiation, the number of infant AIDS deaths over the 2010-2025 period is expected to drop by 23.6% (95% confidence interval [CI]: 22.5-24.5%) at current levels of polymerase chain reaction (PCR) diagnosis, and by 34.2% (95% CI: 32.7-35.6%) if PCR diagnosis increases to 80% of perinatally infected infants at 2 months. However, the pediatric HIV disease burden has shifted toward older children in recent years. The effect of early ART on total pediatric AIDS mortality during the 2010-2025 period is therefore modest: a 9.8% reduction (95% CI: 7.9-12.6%) at current levels of PCR diagnosis, and a 14.2% reduction (95% CI: 11.4-18.2%) if PCR coverage increases to 80% of perinatally infected infants. CONCLUSION: The changes in ART guidelines for infants will have a significant impact on pediatric AIDS mortality at young ages, but further efforts are required to reduce the substantial growing AIDS mortality in older children.

A decline in new HIV infections in South Africa: estimating HIV incidence from three national HIV surveys in 2002, 2005 and 2008.

BACKGROUND: Three national HIV household surveys were conducted in South Africa, in 2002, 2005 and 2008. A novelty of the 2008 survey was the addition of serological testing to ascertain antiretroviral treatment (ART) use. METHODS AND PRINCIPAL FINDINGS: We used a validated mathematical method to estimate the rate of new HIV infections (HIV incidence) in South Africa using nationally representative HIV prevalence data collected in 2002, 2005 and 2008. The observed HIV prevalence levels in 2008 were adjusted for the effect of antiretroviral treatment on survival. The estimated "excess" HIV prevalence due to ART in 2008 was highest among women 25 years and older and among men 30 years and older. In the period 2002-2005, the HIV incidence rate among men and women aged 15-49 years was estimated to be 2.0 new infections each year per 100 susceptible individuals (/100pyar) (uncertainty range: 1.2-3.0/100pyar). The highest incidence rate was among 15-24 year-old women, at 5.5/100pyar (4.5-6.5). In the period 2005-2008, incidence among men and women aged 15-49 was estimated to be 1.3/100 (0.6-2.5/100pyar), although the change from 2002-2005 was not statistically significant. However, the incidence rate among young women aged 15-24 declined by 60% in the same period, to 2.2/100pyar, and this change was statistically significant. There is evidence from the surveys of significant increases in condom use and awareness of HIV status, especially among youth. CONCLUSIONS: Our analysis demonstrates how serial measures of HIV prevalence obtained in population-based surveys can be used to estimate national HIV incidence rates. We also show the need to determine the impact of ART on observed HIV prevalence levels. The estimation of HIV incidence and ART exposure is crucial to disentangle the concurrent impact of prevention and treatment programs on HIV prevalence.

Estimates of eligibility for antiretroviral treatment (ART) and projected ART impact on AIDS mortality among South African educators.

The study assessed the proportion of HIV-infected educators that need antiretroviral treatment (ART) according to current criteria, and estimated the impact of ART on AIDS mortality by modelling scenarios with and without access to ART. Specimens for HIV testing were obtained from 17 088 educators and a sub-sample of 444 venous blood specimens from HIV-positive educators was selected for a CD4 cell count analysis. The Spectrum model package was used for estimating AIDS-associated mortality and projecting the impact of ART scenarios. The results of the CD4 cell count analysis in the HIV-positive educator study population showed that 8% had fewer than 100, 22% fewer than 200, 52% fewer than 350, and 72% fewer than 500 CD4 cells/mm3. Based on the proportion of HIV-positive educators with a CD4 cell count < 200 cells/mm3 we estimated that in 2005 approximately 10 700 educators would need ART according to current SA government guidelines. For the baseline scenario without ART the number of AIDS deaths among HIV-infected educators was projected to increase from 1 992 deaths in 2000 to 5 260 in 2010. The number of projected AIDS deaths in the educator study population was estimated to be 4 414 in 2005, with almost 50% of the AIDS deaths occurring in the 35 - 44 age group. The estimates suggest that in 2005 9.1% of the HIV-infected educators, or 1.2% of the total educator population, will be dying of AIDS. By 2010, a reduction of almost 50% in AIDS deaths was estimated for the treatment scenario with 90% ART coverage, compared with the baseline scenario without treatment. The ART impact scenarios illustrate that a relatively high ART coverage would be needed to ensure a substantial impact of ART on HIV/AIDS-associated mortality.

Epidemiological and demographic HIV/AIDS projections: South Africa.

The Epidemic Projection Package (EPP) recently developed by the UNAIDS Reference Group on Estimates, Models and Projections and the Spectrum model program developed by the Futures Group were used to model the South African HIV epidemic, project future trends in HIV/AIDS and estimate the demographic impact of AIDS. The national HIV prevalence surveys among pregnant women from 1990-2001 and the first national, population-based HIV survey in 2002 served as the data sets used to calibrate the input HIV prevalence values for the model. The scenario created by the model showed that a dramatic rise in HIV prevalence during the 1990s has peaked in 2002 with 4.69 million infected people and it is projected that the epidemic in South Africa has now begun to level off. Adult (15-49 years) incidence rates have decreased substantially in the past five years since 1997 (4.2%) and are expected to reach a level of 1.7% in 2003. The annual number of deaths due to AIDS is projected to peak with 487 320 AIDS deaths in the year 2008. By 2020, the total population of South Africa is expected to be 23% smaller than it would be without AIDS, however, a negative population growth rate is not expected during the projection period. Life expectancy at birth is expected to hit a low of 45.6 years in the time period 2005-2010, which is 22 years less than it would have been in the absence of AIDS. Ten years from now over 2.5 million AIDS orphans are projected for South Africa. Models play an important role in estimating HIV variables that are difficult to measure. Projections of the future HIV/AIDS burden in South Africa underscore the importance of acting now to reduce the number of new infections and plan for medical and social care needs.