The impact and importance of voluntary counselling and testing for HIV in sub-Saharan Africa

Voluntary counselling and testing (VCT) for HIV is promoted as a primary prevention strategy to reduce the heterosexual transmission of HIV in sub-Saharan Africa. A theoretical framework for the determinants of uptake of VCT and behavioural outcomes following VCT was developed. Demographic and Health Survey (DHS) data collected from 2003 to 2005 from ten countries were analysed to test the framework by comparing nationally representative trends in uptake of testing. Data from a population-based open cohort study in Manicaland, Zimbabwe was also used to test this framework by analysing trends in sexual behaviour and behaviour change associated with having received VCT. DHS data indicate that knowledge of serostatus varied widely between countries and ranged from 2% among women in Guinea to 27% among women in Rwanda. Despite these varied levels of testing, univariate analysis showed the profile of testers to be remarkably similar across countries with respect to socio-demographic characteristics. Adjusted analyses indicate that a secondary or higher level of education and an awareness that treatment exists are key determinants of uptake of VCT. Uptake of VCT in the Manicaland cohort is low, at 8.6% in the most recent survey. Against a background of behavioural risk reduction in the general population, there was no evidence for additional risk reduction associated with having received VCT in the Manicaland cohort. This work provides a baseline for monitoring trends in testing and exploring changes in the profile of those who get tested as provision of testing and treatment services increase. Within the Manicaland study population, these results do not provide evidence that VCT can promote behavioural risk reduction, in a context of background reductions in risk. Uptake of VCT is expected to increase in this population as treatment becomes available. It is important that VCT services are monitored and evaluated and the importance of risk reduction is emphasised through good quality counselling. To succeed as a prevention measure, VCT must attain a high coverage of the sexually active population and lead to sustained risk reduction among both infected and uninfected individuals

The new role of antiretrovirals in combination HIV prevention: a mathematical modelling analysis.

BACKGROUND AND OBJECTIVES: Antiretroviral drugs can reduce HIV acquisition among uninfected individuals (as pre-exposure prophylaxis: PrEP) and reduce onward transmission among infected individuals (as antiretroviral treatment: ART). We estimate the potential impact and cost-effectiveness of antiretroviral-based HIV prevention strategies. DESIGN AND METHODS: We developed and analysed a mathematical model of a hyperendemic setting with relatively low levels of condom use. We estimated the prevention impact and cost of various PrEP interventions, assuming a fixed amount of spending on PrEP; investigated the optimal role of PrEP and earlier ART in terms of epidemiological impact and cost; and systematically explored the impact of earlier ART and PrEP, in combination with medical male circumcision services; on HIV transmission. RESULTS: A PrEP intervention is unlikely to generate a large reduction in HIV incidence, unless the cost is substantially reduced. In terms of infections averted and quality adjusted life years gained, at a population-level maximal cost-effectiveness is achieved by providing ART to more infected individuals earlier rather than providing PrEP to uninfected individuals. However, early ART alone cannot reduce HIV incidence to very low levels and PrEP can be used cost-effectively in addition to earlier ART to reduce incidence further. If implemented in combination and at ambitious coverage levels, medical male circumcision, earlier ART and PrEP could produce dramatic declines in HIV incidence, but not stop transmission completely. CONCLUSION: A combination prevention approach based on proven-efficacy interventions provides the best opportunity for achieving the much hoped for prevention advance and curbing the spread of HIV

Distinct HIV discordancy patterns by epidemic size in stable sexual partnerships in sub-Saharan Africa

OBJECTIVE: To describe patterns of HIV infection among stable sexual partnerships across sub-Saharan Africa (SSA). METHODS: The authors defined measures of HIV discordancy and conducted a comprehensive quantitative assessment of discordancy among stable partnerships in 20 countries in SSA through an analysis of the Demographic and Health Survey data. RESULTS: HIV prevalence explained at least 50% of the variation in HIV discordancy, with two distinct patterns of discordancy emerging based on HIV prevalence being roughly smaller or larger than 10%. In low-prevalence countries, approximately 75% of partnerships affected by HIV are discordant, while only about half of these are discordant in high-prevalence countries. Out of each 10 HIV infected persons, two to five are engaged in discordant partnerships in low-prevalence countries compared with one to three in high-prevalence countries. Among every 100 partnerships in the population, one to nine are affected by HIV and zero to six are discordant in low-prevalence countries compared with 16-45 and 9-17, respectively, in high-prevalence countries. Finally, zero to four of every 100 sexually active adults are engaged in a discordant partnership in low-prevalence countries compared with six to eight in high-prevalence countries. CONCLUSIONS: In high-prevalence countries, a large fraction of stable partnerships were affected by HIV and half were discordant, whereas in low-prevalence countries, fewer stable partnerships were affected by HIV but a higher proportion of them were discordant. The findings provide a global view of HIV infection among stable partnerships in SSA but imply complex considerations for rolling out prevention interventions targeting discordant partnerships

Voluntary counselling and testing: uptake, impact on sexual behaviour, and HIV incidence in a rural Zimbabwean cohort.

OBJECTIVES: To examine the determinants of uptake of voluntary counselling and testing (VCT) services, to assess changes in sexual risk behaviour following VCT, and to compare HIV incidence amongst testers and non-testers. METHODS: Prospective population-based cohort study of adult men and women in the Manicaland province of eastern Zimbabwe. Demographic, socioeconomic, sexual behaviour and VCT utilization data were collected at baseline (1998-2000) and follow-up (3 years later). HIV status was determined by HIV-1 antibody detection. In addition to services provided by the government and non-governmental organizations, a mobile VCT clinic was available at study sites. RESULTS: Lifetime uptake of VCT increased from under 6% to 11% at follow-up. Age, increasing education and knowledge of HIV were associated with VCT uptake. Women who took a test were more likely to be HIV positive and to have greater HIV knowledge and fewer total lifetime partners. After controlling for demographic characteristics, sexual behaviour was not independently associated with VCT uptake. Women who tested positive reported increased consistent condom use in their regular partnerships. However, individuals who tested negative were more likely to adopt more risky behaviours in terms of numbers of partnerships in the last month, the last year and in concurrent partnerships. HIV incidence during follow-up did not differ between testers and non-testers. CONCLUSION: Motivation for VCT uptake was driven by knowledge and education rather than sexual risk. Increased sexual risk following receipt of a negative result may be a serious unintended consequence of VCT. It should be minimized with appropriate pre- and post-test counselling

Estimating the Cost-Effectiveness of Pre-Exposure Prophylaxis to Reduce HIV-1 and HSV-2 Incidence in HIV-Serodiscordant Couples in South Africa

<div><p>Objective</p><p>To estimate the cost-effectiveness of daily oral tenofovir-based PrEP, with a protective effect against HSV-2 as well as HIV-1, among HIV-1 serodiscordant couples in South Africa.</p><p>Methods</p><p>We incorporated HSV-2 acquisition, transmission, and interaction with HIV-1 into a microsimulation model of heterosexual HIV-1 serodiscordant couples in South Africa, with use of PrEP for the HIV-1 uninfected partner prior to ART initiation for the HIV-1 1infected partner, and for one year thereafter.</p><p>Results</p><p>We estimate the cost per disability-adjusted life-year (DALY) averted for two scenarios, one in which PrEP has no effect on reducing HSV-2 acquisition, and one in which there is a 33% reduction. After a twenty-year intervention, the cost per DALY averted is estimated to be $10,383 and$9,757, respectively – a 6% reduction, given the additional benefit of reduced HSV-2 acquisition. If all couples are discordant for both HIV-1 and HSV-2, the cost per DALY averted falls to $1,445, which shows that the impact is limited by HSV-2 concordance in couples.</p><p>Conclusion</p><p>After a 20-year PrEP intervention, the cost per DALY averted with a reduction in HSV-2 is estimated to be modestly lower than without any effect, providing an increase of health benefits in addition to HIV-1 prevention at no extra cost. The small degree of the effect is in part due to a high prevalence of HSV-2 infection in HIV-1 serodiscordant couples in South Africa.</p></div

Difference in cost per DALY averted for two PrEP scenarios.

<p>The discounted cost per DALY averted for a 20-year PrEP intervention with no assumed protection against HSV-2 acquisition and with 33% protection (both relative to a baseline scenario of no PrEP and ART initiation at a CD4 count of 350 cells/μl). The inset is the difference between the two scenarios in the mean number of DALYs averted per couple over the intervention period. The horizontal lines represent WHO thresholds for cost-effectiveness at three times GDP ($34,320) and one times GDP ($11,440) for South Africa.</p

Sensitivity analysis for factors affecting the cost per DALY averted.

<p>Univariate sensitivity analysis for factors affecting the cost per DALY averted at the end of a 20-year PrEP intervention, with a baseline assumption of a 33% protection against acquisition of HSV-2 (the vertical line at $9,757). The bars titled <i>ART Initiation CD4 <500</i> and <i>ART Initiation Immediately</i> assume increased thresholds for ART initiation. The bar titled <i>PrEP Adherence</i> assumes HIV-uninfected individuals are 50$150/PY or $350/PY, and the <i>PrEP Program Cost Perspective</i> bar assumes that the cost of the PrEP intervention is separate from funding for treatment, and does not include savings from reduced ART need due to averted HIV infections.</p

Key assumptions and parameters used in the model.

<p>^aMean time elapsed between entering category (CD4 cell count reaching value of upper bound) and exiting category (CD4 cell count drops below value of lower bound).</p><p>^bBaseline transmission probability is from an asymptomatic, non-pregnant woman to an uncircumcised man.</p><p>Key assumptions and parameters used in the model.</p

Transformation of HIV from pandemic to low-endemic levels: a public health approach to combination prevention.

Large declines in HIV incidence have been reported since 2001, and scientific advances in HIV prevention provide strong hope to reduce incidence further. Now is the time to replace the quest for so-called silver bullets with a public health approach to combination prevention that understands that risk is not evenly distributed and that effective interventions can vary by risk profile. Different countries have different microepidemics, with very different levels of transmission and risk groups, changing over time. Therefore, focus should be on high-transmission geographies, people at highest risk for HIV, and the package of interventions that are most likely to have the largest effect in each different microepidemic. Building on the backbone of behaviour change, condom use, and medical male circumcision, as well as expanded use of antiretroviral drugs for infected people and pre-exposure prophylaxis for uninfected people at high risk of infection, it is now possible to consider the prospect of what would be one of the most remarkable achievements in the history of public health: reduction of HIV transmission from a pandemic to low-level endemicity