Estimating HIV pre-exposure prophylaxis need and impact in Malawi, Mozambique and Zambia: A geospatial and risk-based analysis.

BACKGROUND: Pre-exposure prophylaxis (PrEP), a WHO-recommended HIV prevention method for people at high risk for acquiring HIV, is being increasingly implemented in many countries. Setting programmatic targets, particularly in generalised epidemics, could incorporate estimates of the size of the population likely to be eligible for PrEP using incidence-based thresholds. We estimated the proportion of men and women who would be eligible for PrEP and the number of HIV infections that could be averted in Malawi, Mozambique, and Zambia using prioritisation based on age, sex, geography, and markers of risk. METHODS AND FINDINGS: We analysed the latest nationally representative Demographic and Health Surveys (DHS) of Malawi, Mozambique, and Zambia to determine the proportion of adults who report behavioural markers of risk for HIV infection. We used prevalence ratios (PRs) to quantify the association of these factors with HIV status. Using a multiplier method, we combined these proportions with the number of new HIV infections by district, derived from district-level modelled HIV estimates. Based on these numbers, different scenarios were analysed for the minimum number of person-years on PrEP needed to prevent 1 HIV infection (NNP). An estimated total of 38,000, 108,000, and 46,000 new infections occurred in Malawi, Mozambique, and Zambia in 2016, corresponding with incidence rates of 0.43, 0.63, and 0.57 per 100 person-years. In these countries, 9%-20% of new infections occurred among people with a sexually transmitted infection (STI) in the past 12 months and 40%-42% among people with either an STI or a non-regular sexual partner (NP) in the past 12 months (STINP). The models estimate that around 50% of new infections occurred in districts with incidence rates ≥1.0% in Mozambique and Zambia and ≥0.5% in Malawi. In Malawi, Mozambique, and Zambia, 35.1%, 21.9%, and 12.5% of the population live in these high-incidence districts. In the most parsimonious scenario, if women aged 15-34 years and men 20-34 years with an STI in the past 12 months living in high-incidence districts were to take PrEP, it would take a minimum of 65.8 person-years on PrEP to avert 1 HIV infection per year in Malawi, 35.2 in Mozambique, and 16.4 in Zambia. Our findings suggest that 3,300, 5,200, and 1,700 new infections could be averted per year in the 3 countries, respectively. Limitations of our study are that these values are based on modelled estimates of HIV incidence and self-reported behavioural risk factors from national surveys. CONCLUSIONS: A large proportion of new HIV infections in these 3 African countries were estimated to occur among people who had either an STI or an NP in the past year, providing a straightforward means to set PrEP targets. Greater prioritisation of PrEP by district, sex, age, and behavioural risk factors resulted in lower NNPs thereby increasing PrEP cost-effectiveness, but also diminished the overall impact on reducing new infections.

What will it take for the Global Plan priority countries in Sub-Saharan Africa to eliminate mother-to-child transmission of HIV?

BACKGROUND: The 2016 'Start Free, Stay Free, AIDS Free' global agenda, builds on the 2011-2015 'Global Plan'. It prioritises 22 countries where 90% of the world's HIV-positive pregnant women live and aims to eliminate vertical  transmission of HIV (EMTCT) and to keep mothers alive. By 2019, no Global Plan priority country had achieved EMTCT; however, 11 non-priority countries had. This paper synthesises the characteristics of the first four countries validated for EMTCT, and of the 21 Global Plan priority countries located in Sub-Saharan Africa (SSA). We consider what drives vertical transmission of HIV (MTCT) in the 21 SSA Global Plan priority countries. METHODS: A literature review, using PubMed, Science direct and the google search engine was conducted to obtain global and national-level information on current HIV-related context and health system characteristics of the first four EMTCT-validated countries and the 21 SSA Global Plan priority countries. Data representing only one clinic, hospital or region were excluded. Additionally, key global experts working on EMTCT were contacted to obtain clarification on published data. We applied three theories (the World Health Organisation's building blocks to strengthen health systems, van Olmen's Health System Dynamics framework and Baral's socio-ecological model for HIV risk) to understand and explain the differences between EMTCT-validated and non-validated countries. Additionally, structural equation modelling (SEM) and linear regression were used to explain associations between infant HIV exposure, access to antiretroviral therapy and two outcomes: (i) percent MTCT and (iii) number of new paediatric HIV infections per 100 000 live births (paediatric HIV case rate). RESULTS: EMTCT-validated countries have lower HIV prevalence, less breastfeeding, fewer challenges around leadership, governance within the health sector or country, infrastructure and service delivery compared with Global Plan priority countries. Although by 2016 EMTCT-validated countries and Global Plan priority countries had adopted a public health approach to HIV prevention, recommending lifelong antiretroviral therapy (ART) for all HIV-positive pregnant and lactating women, EMCT-validated countries had also included contact tracing such as assisted partner notification, and had integrated maternal and child health (MCH) and sexual and reproductive health (SRH) services, with services for HIV infection, sexually transmitted infections, and viral hepatitis. Additionally, Global Plan priority countries have limited data on key SRH indicators such as unmet need for family planning, with variable coverage of antenatal care, HIV testing and triple antiretroviral therapy (ART) and very limited contact tracing. Structural equation modelling (SEM) and linear regression analysis demonstrated that ART access protects against percent MTCT (p<0.001); in simple linear regression it is 53% protective against percent MTCT. In contrast, SEM demonstrated that the case rate was driven by the number of HIV exposed infants (HEI) i.e. maternal HIV prevalence (p<0.001). In linear regression models, ART access alone explains only 17% of the case rate while HEI alone explains 81% of the case rate. In multiple regression, HEI and ART access accounts for 83% of the case rate, with HEI making the most contribution (coef. infant HIV exposure=82.8, 95% CI: 64.6, 101.1, p<0.001 vs coef. ART access=-3.0, 95% CI: -6.2, 0.3, p=0.074). CONCLUSION: Reducing infant HIV exposure, is critical to reducing the paediatric HIV case rate; increasing ART access is critical to reduce percent MTCT. Additionally, our study of four validated countries underscores the importance of contact tracing, strengthening programme monitoring, leadership and governance, as these are potentially-modifiable factors.

Prevention of Mother-to-Child Transmission of HIV and Paediatric HIV Care and Treatment Monitoring: From Measuring Process to Impact and Elimination of Mother-to-Child Transmission of HIV.

Progress towards achievement of global targets for the prevention of mother-to-child transmission of HIV (PMTCT) and paediatric HIV care and treatment is an integral part of global and national HIV and AIDS responses. This paper documents the development of the global and national monitoring and reporting systems for PMTCT and paediatric HIV care and treatment programmes, achievements and remaining challenges. A review of the development of the monitoring and reporting process since 2002-2016 was conducted using existing published literature and taking into account changes in WHO HIV treatment guidelines, global HIV goals and targets, programmatic and methodological developments, and increased need for interagency partnerships, coordination and harmonization of global monitoring and reporting mechanisms. The number and type of indicators reported increased and evolved from monitoring of existence of national policies and guidelines, service delivery sites and trained health workers and coverage of PMTCT and paediatric HIV interventions to measuring outcomes and impact in reducing new HIV infections and AIDS related deaths, including efforts to validate elimination of mother-to-child transmission of HIV. These changes were required to mirror changes in WHO and national PMTCT and HIV treatment guidelines. The number of countries reporting PMTCT coverage increased from 53 in 2003 to over 130 in 2015. National monitoring processes have also expanded in scope and the capacity to report on disaggregated data by type of ARV regimen and for paediatric HIV care and treatment has increased. Monitoring of PMTCT and paediatric HIV programmes has contributed a rich body of evidence that helped monitor how quickly countries were adopting and implementing the latest WHO HIV treatment guidelines for pregnant and breastfeeding women and children. The reported data and experiences were instrumental in shaping global policies, national programmes, and investment choices.

The Network Survival Method for Estimating Adult Mortality: Evidence From a Survey Experiment in Rwanda.

Adult death rates are a critical indicator of population health and well-being. Wealthy countries have high-quality vital registration systems, but poor countries lack this infrastructure and must rely on estimates that are often problematic. In this article, we introduce the network survival method, a new approach for estimating adult death rates. We derive the precise conditions under which it produces consistent and unbiased estimates. Further, we develop an analytical framework for sensitivity analysis. To assess the performance of the network survival method in a realistic setting, we conducted a nationally representative survey experiment in Rwanda (n = 4,669). Network survival estimates were similar to estimates from other methods, even though the network survival estimates were made with substantially smaller samples and are based entirely on data from Rwanda, with no need for model life tables or pooling of data from other countries. Our analytic results demonstrate that the network survival method has attractive properties, and our empirical results show that this method can be used in countries where reliable estimates of adult death rates are sorely needed.

Quantity Versus Quality: A Survey Experiment to Improve the Network Scale-up Method.

The network scale-up method is a promising technique that uses sampled social network data to estimate the sizes of epidemiologically important hidden populations, such as sex workers and people who inject illicit drugs. Although previous scale-up research has focused exclusively on networks of acquaintances, we show that the type of personal network about which survey respondents are asked to report is a potentially crucial parameter that researchers are free to vary. This generalization leads to a method that is more flexible and potentially more accurate. In 2011, we conducted a large, nationally representative survey experiment in Rwanda that randomized respondents to report about one of 2 different personal networks. Our results showed that asking respondents for less information can, somewhat surprisingly, produce more accurate size estimates. We also estimated the sizes of 4 key populations at risk for human immunodeficiency virus infection in Rwanda. Our estimates were higher than earlier estimates from Rwanda but lower than international benchmarks. Finally, in this article we develop a new sensitivity analysis framework and use it to assess the possible biases in our estimates. Our design can be customized and extended for other settings, enabling researchers to continue to improve the network scale-up method.

Estimating the impact of the US President's Emergency Plan for AIDS Relief on HIV treatment and prevention programmes in Africa.

BACKGROUND: Since 2004, the US President's Emergency Plan for AIDS Relief (PEPFAR) has supported the tremendous scale-up of HIV prevention, care and treatment services, primarily in sub-Saharan Africa. We evaluate the impact of antiretroviral treatment (ART), prevention of mother-to-child transmission (PMTCT) and voluntary medical male circumcision (VMMC) programmes on survival, mortality, new infections and the number of orphans from 2004 to 2013 in 16 PEPFAR countries in Africa. METHODS: PEPFAR indicators tracking the number of persons receiving ART for their own health, ART regimens for PMTCT and biomedical prevention of HIV through VMMC were collected across 16 PEPFAR countries. To estimate the impact of PEPFAR programmes for ART, PMTCT and VMMC, we compared the current scenario of PEPFAR-supported interventions to a counterfactual scenario without PEPFAR, and assessed the number of life years gained (LYG), number of orphans averted and HIV infections averted. Mathematical modelling was conducted using the SPECTRUM modelling suite V.5.03. RESULTS: From 2004 to 2013, PEPFAR programmes provided support for a cumulative number of 24 565 127 adults and children on ART, 4 154 878 medical male circumcisions, and ART for PMTCT among 4 154 478 pregnant women in 16 PEPFAR countries. Based on findings from the model, these efforts have helped avert 2.9 million HIV infections in the same period. During 2004-2013, PEPFAR ART programmes alone helped avert almost 9 million orphans in 16 PEPFAR countries and resulted in 11.6 million LYG. CONCLUSIONS: Modelling results suggest that the rapid scale-up of PEPFAR-funded ART, PMTCT and VMMC programmes in Africa during 2004-2013 led to substantially fewer new HIV infections and orphaned children during that time and longer lives among people living with HIV. Our estimates do not account for the impact of the PEPFAR-funded non-biomedical interventions such as behavioural and structural interventions included in the comprehensive HIV prevention, care and treatment strategy used by PEPFAR countries. Therefore, the number of HIV infections and orphans averted and LYG may be underestimated by these models.

Updated Data and Methods for the 2023 UNAIDS HIV Estimates.

ABSTRACT: Each year, supported by the Joint United Nations Programme on HIV/AIDS (UNAIDS), country teams across the globe produce estimates that chart the state of their HIV epidemics. In 2023, HIV estimates were available for 174 countries, accounting for 99% of the global population, of which teams from 150 countries actively engaged in this process. The methods used to derive these estimates are developed under the guidance of the UNAIDS Reference Group on Estimates, Modeling, and Projections (www.epidem.org). Updates to these methods and epidemiological analyses that inform parameters and assumptions are documented in this supplement.

Differences in Breastfeeding Duration by Maternal HIV Status: A Pooled Analysis of Nationally Representative Surveys in Sub-Saharan Africa.

BACKGROUND: Breastfeeding improves child survival but is a source of mother-to-child HIV transmission among women with unsuppressed HIV infection. Estimated HIV incidence in children is sensitive to breastfeeding duration among mothers living with HIV (MLHIV). Breastfeeding duration may vary according to maternal HIV status. SETTING: Sub-Saharan Africa. METHODS: We analyzed pooled data from nationally representative household surveys conducted during 2003-2019 that included HIV testing and elicited breastfeeding practices. We fitted survival models of breastfeeding duration by country, year, and maternal HIV status for 4 sub-Saharan African regions (Eastern, Central, Southern, and Western). RESULTS: Data were obtained from 65 surveys in 31 countries. In 2010, breastfeeding in the first month of life ("initial breastfeeding") among MLHIV ranged from 69.1% (95% credible interval: 68-79.9) in Southern Africa to 93.4% (92.7-98.0) in Western Africa. Median breastfeeding duration among MLHIV was the shortest in Southern Africa at 15.6 (14.2-16.3) months and the longest in Eastern Africa at 22.0 (21.7-22.5) months. By comparison, HIV-negative mothers were more likely to breastfeed initially (91.0%-98.7% across regions) and for longer duration (median 18.3-24.6 months across regions). Initial breastfeeding and median breastfeeding duration decreased during 2005-2015 in most regions and did not increase in any region regardless of maternal HIV status. CONCLUSIONS: MLHIV in sub-Saharan Africa are less likely to breastfeed initially and stop breastfeeding sooner than HIV-negative mothers. Since 2020, UNAIDS-supported HIV estimates have accounted for this shorter breastfeeding exposure among HIV-exposed children. MLHIV need support to enable optimal breastfeeding practices and to adhere to antiretroviral therapy for HIV treatment and prevention of postnatal mother-to-child transmission.

Triangulation of Routine Antenatal HIV Prevalence Data and Adjusted HIV Estimates in Mozambique.

BACKGROUND: Routine health system data are central to monitoring HIV trends. In Mozambique, the reported number of women receiving antenatal care (ANC) and antiretroviral therapy for prevention of mother-to-child transmission (PMTCT) has exceeded the Spectrum-estimated number of pregnant women since 2017. In some provinces, reported HIV prevalence in pregnant women has declined faster than epidemiologically plausible. We hypothesized that these issues are linked and caused by programmatic overenumeration of HIV-negative pregnant women at ANC. METHODS: We triangulated program-reported ANC client numbers with survey-based fertility estimates and facility birth data adjusted for the proportion of facility births. We used survey-reported ANC attendance to produce adjusted time series of HIV prevalence in pregnant women, adjusted for hypothesized program double counting. We calibrated the Spectrum HIV estimation models to adjusted HIV prevalence data to produce adjusted adult and pediatric HIV estimates. RESULTS: ANC client numbers were not consistent with facility birth data or modeled population estimates indicating ANC data quality issues in all provinces. Adjusted provincial ANC HIV prevalence in 2021 was median 45% [interquartile range 35%-52% or 2.3 percentage points (interquartile range 2.5-3.5)] higher than reported HIV prevalence. In 2021, calibrating to adjusted antenatal HIV prevalence lowered PMTCT coverage to less than 100% in most provinces and increased the modeled number of new child infections by 35%. The adjusted results better reconciled adult and pediatric antiretroviral treatment coverage and antenatal HIV prevalence with regional fertility estimates. CONCLUSIONS: Adjusting HIV prevalence in pregnant women using nationally representative household survey data on ANC attendance produced estimates more consistent with surveillance data. The number of children living with HIV in Mozambique has been substantially underestimated because of biased routine ANC prevalence. Renewed focus on HIV surveillance among pregnant women would improve PMTCT coverage and pediatric HIV estimates.

New HIV Infections Among Key Populations and Their Partners in 2010 and 2022, by World Region: A Multisources Estimation.

BACKGROUND: Previously, The Joint United Nations Programme on HIV/AIDS estimated proportions of adult new HIV infections among key populations (KPs) in the last calendar year, globally and in 8 regions. We refined and updated these, for 2010 and 2022, using country-level trend models informed by national data. METHODS: Infections among 15-49 year olds were estimated for sex workers (SWs), male clients of female SW, men who have sex with men (MSM), people who inject drugs (PWID), transgender women (TGW), and non-KP sex partners of these groups. Transmission models used were Goals (71 countries), AIDS Epidemic Model (13 Asian countries), Optima (9 European and Central Asian countries), and Thembisa (South Africa). Statistical Estimation and Projection Package fits were used for 15 countries. For 40 countries, new infections in 1 or more KPs were approximated from first-time diagnoses by the mode of transmission. Infection proportions among nonclient partners came from Goals, Optima, AIDS Epidemic Model, and Thembisa. For remaining countries and groups not represented in models, median proportions by KP were extrapolated from countries modeled within the same region. RESULTS: Across 172 countries, estimated proportions of new adult infections in 2010 and 2022 were both 7.7% for SW, 11% and 20% for MSM, 0.72% and 1.1% for TGW, 6.8% and 8.0% for PWID, 12% and 10% for clients, and 5.3% and 8.2% for nonclient partners. In sub-Saharan Africa, proportions of new HIV infections decreased among SW, clients, and non-KP partners but increased for PWID; elsewhere these groups' 2010-to-2022 differences were opposite. For MSM and TGW, the proportions increased across all regions. CONCLUSIONS: KPs continue to have disproportionately high HIV incidence.

Guidance for triangulating data and estimates of HIV prevalence among pregnant women and coverage of PMTCT using the Spectrum AIDS Impact Module.

Background: Most countries use the Spectrum AIDS Impact Module (Spectrum-AIM), antenatal care routine HIV testing, and antiretroviral treatment data to estimate HIV prevalence among pregnant women. Non-representative programme data may lead to inaccurate estimates HIV prevalence and treatment coverage for pregnant women. Setting: 154 locations in 126 countries. Methods: Using 2023 UNAIDS HIV estimates, we calculated three ratios: (1) HIV prevalence among pregnant women to all women 15-49y (prevalence), (2) ART coverage before pregnancy to women 15-49y ART coverage (ART pre-pregnancy), and (3) ART coverage at delivery to women 15-49y ART coverage (PMTCT coverage). We developed an algorithm to identify and adjust inconsistent results within regional ranges in Spectrum-AIM, illustrated using Burkina Faso's estimates. Results: In 2022, the mean regional ratio of prevalence among pregnant women to all women ranged from 0.68 to 0.95. ART coverage pre-pregnancy ranged by region from 0.40 to 1.22 times ART coverage among all women. Mean regional PMTCT coverage ratios ranged from 0.85 to 1.51. The prevalence ratio in Burkina Faso was 1.59, above the typical range 0.62-1.04 in western and central Africa. Antenatal clinics reported more PMTCT recipients than estimated HIV-positive pregnant women from 2015 to 2019. We adjusted inputted PMTCT programme data to enable consistency of HIV prevalence among pregnant women from programmatic routine HIV testing at antenatal clinics with values typical for Western and central Africa. Conclusion: These ratios offer Spectrum-AIM users a tool to gauge the consistency of their HIV prevalence and treatment coverage estimates among pregnant women with other countries in the region.

Neurodevelopment among children exposed to HIV and uninfected in sub-Saharan Africa.

INTRODUCTION: The population of 16 million children exposed to HIV and uninfected (CHEU) under 15 years of age continues to expand rapidly, and the estimated prevalence of CHEU exceeds 20% in several countries in sub-Saharan Africa with high HIV prevalence. Some evidence suggests that CHEU experience suboptimal neurodevelopmental outcomes compared to children born to women without HIV. In this commentary, we discuss the latest research on biologic and socio-behavioural factors associated with neurodevelopmental outcomes among CHEU. DISCUSSION: Some but not all studies have noted that CHEU are at risk of poorer neurodevelopment across multiple cognitive domains, most notably in language and motor skills, in diverse settings, ages and using varied assessment tools. Foetal HIV exposure can adversely influence infant immune function, structural brain integrity and growth trajectories. Foetal exposure to antiretrovirals may also influence outcomes. Moreover, general, non-CHEU-specific risk factors for poor neurodevelopment, such as preterm birth, food insecurity, growth faltering and household violence, are amplified among CHEU; addressing these factors will require multi-factorial solutions. There is a need for rigorous harmonised approaches to identify children at the highest risk of delay. In high-burden HIV settings, existing maternal child health programmes serving the general population could adopt structured early child development programmes that educate healthcare workers on CHEU-specific risk factors and train them to conduct rapid neurodevelopmental screening tests. Community-based interventions targeting parent knowledge of optimal caregiving practices have shown to be successful in improving neurodevelopmental outcomes in children and should be adapted for CHEU. CONCLUSIONS: CHEU in sub-Saharan Africa have biologic and socio-behavioural factors that may influence their neurodevelopment, brain maturation, immune system and overall health and wellbeing. Multidisciplinary research is needed to disentangle complex interactions between contributing factors. Common environmental and social risk factors for suboptimal neurodevelopment in the general population are disproportionately magnified within the CHEU population, and it is, therefore, important to draw on existing knowledge when considering the socio-behavioural pathways through which HIV exposure could impact CHEU neurodevelopment. Approaches to identify children at greatest risk for poor outcomes and multisectoral interventions are needed to ensure optimal outcomes for CHEU in sub-Saharan Africa.

Antiretroviral postnatal prophylaxis to prevent HIV vertical transmission: present and future strategies.

INTRODUCTION: Maternal antiretroviral therapy (ART) with viral suppression prior to conception, during pregnancy and throughout the breastfeeding period accompanied by infant postnatal prophylaxis (PNP) forms the foundation of current approaches to preventing vertical HIV transmission. Unfortunately, infants continue to acquire HIV infections, with half of these infections occurring during breastfeeding. A consultative meeting of stakeholders was held to review the current state of PNP globally, including the implementation of WHO PNP guidelines in different settings and identifying the key factors affecting PNP uptake and impact, with an aim to optimize future innovative strategies. DISCUSSION: WHO PNP guidelines have been widely implemented with adaptations to the programme context. Some programmes with low rates of antenatal care attendance, maternal HIV testing, maternal ART coverage and viral load testing capacity have opted against risk-stratification and provide an enhanced PNP regimen for all infants exposed to HIV, while other programmes provide infant daily nevirapine antiretroviral (ARV) prophylaxis for an extended duration to cover transmission risk throughout the breastfeeding period. A simplified risk stratification approach may be more relevant for high-performing vertical transmission prevention programmes, while a simplified non-risk stratified approach may be more appropriate for sub-optimally performing programmes given implementation challenges. In settings with concentrated epidemics, where the epidemic is often driven by key populations, infants who are found to be exposed to HIV should be considered at high risk for HIV acquisition. All settings could benefit from newer technologies that promote retention during pregnancy and throughout the breastfeeding period. There are several challenges in enhanced and extended PNP implementation, including ARV stockouts, lack of appropriate formulations, lack of guidance on alternative ARV options for prophylaxis, poor adherence, poor documentation, inconsistent infant feeding practices and in inadequate retention throughout the duration of breastfeeding. CONCLUSIONS: Tailoring PNP strategies to a programmatic context may improve access, adherence, retention and HIV-free outcomes of infants exposed to HIV. Newer ARV options and technologies that enable simplification of regimens, non-toxic potent agents and convenient administration, including longer-acting formulations, should be prioritized to optimize the effect of PNP in the prevention of vertical HIV transmission.

Spatio-temporal estimates of HIV risk group proportions for adolescent girls and young women across 13 priority countries in sub-Saharan Africa.

The Global AIDS Strategy 2021-2026 identifies adolescent girls and young women (AGYW) as a priority population for HIV prevention, and recommends differentiating intervention portfolios geographically based on local HIV incidence and individual risk behaviours. We estimated prevalence of HIV risk behaviours and associated HIV incidence at health district level among AGYW living in 13 countries in sub-Saharan Africa. We analysed 46 geospatially-referenced national household surveys conducted between 1999-2018 across 13 high HIV burden countries in sub-Saharan Africa. Female survey respondents aged 15-29 years were classified into four risk groups (not sexually active, cohabiting, non-regular or multiple partner[s] and female sex workers [FSW]) based on reported sexual behaviour. We used a Bayesian spatio-temporal multinomial regression model to estimate the proportion of AGYW in each risk group stratified by district, year, and five-year age group. Using subnational estimates of HIV prevalence and incidence produced by countries with support from UNAIDS, we estimated new HIV infections in each risk group by district and age group. We then assessed the efficiency of prioritising interventions according to risk group. Data consisted of 274,970 female survey respondents aged 15-29. Among women aged 20-29, cohabiting (63.1%) was more common in eastern Africa than non-regular or multiple partner(s) (21.3%), while in southern countries non-regular or multiple partner(s) (58.9%) were more common than cohabiting (23.4%). Risk group proportions varied substantially across age groups (65.9% of total variation explained), countries (20.9%), and between districts within each country (11.3%), but changed little over time (0.9%). Prioritisation based on behavioural risk, in combination with location- and age-based prioritisation, reduced the proportion of population required to be reached in order to find half of all expected new infections from 19.4% to 10.6%. FSW were 1.3% of the population but 10.6% of all expected new infections. Our risk group estimates provide data for HIV programmes to set targets and implement differentiated prevention strategies outlined in the Global AIDS Strategy. Successfully implementing this approach would result in more efficiently reaching substantially more of those at risk for infections.

HIV prevalence in transgender populations and cisgender men who have sex with men in sub-Saharan Africa 2010-2022: a meta-analysis.

Introduction: The Global AIDS Strategy 2021-2026 calls for equitable and equal access to HIV prevention and treatment programmes for all populations to reduce HIV incidence and end HIV/AIDS as a public health threat by 2030. Transgender populations (TGP), including transmen (TGM) and transwomen (TGW) are populations that have been marginalised and are at high risk of HIV infection in sub-Saharan Africa (SSA). Limited surveillance data on HIV among TGP are available in the region to guide programmatic responses and policymaking. Surveillance data on cisgender men who have sex with men (cis-MSM) are comparatively abundant and may be used to infer TGP HIV prevalence. Methods: Data from key population surveys conducted in SSA between 2010-2022 were identified from existing databases and survey reports. Studies that collected HIV prevalence on both TGP and cis-MSM populations were analysed in a random effect meta-analysis to estimate the ratio of cis-MSM:TGW HIV prevalence. Results: Eighteen studies were identified encompassing 8,052 TGW and 19,492 cis-MSM. TGW HIV prevalence ranged from 0-71.6% and cis-MSM HIV prevalence from 0.14-55.7%. HIV prevalence in TGW was 50% higher than in cis-MSM (prevalence ratio (PR) 1.50 95% CI 1.26-1.79). TGW HIV prevalence was highly correlated with year/province-matched cis-MSM HIV prevalence (R2 = 0.62), but poorly correlated with year/province-matched total population HIV prevalence (R2 = 0.1). Five TGM HIV prevalence estimates were identified ranging from 1-24%. Insufficient TGM data were available to estimate cis-MSM:TGM HIV prevalence ratios. Conclusion: Transgender women experience a significantly greater HIV burden than cis-MSM in SSA. Bio-behavioural surveys designed and powered to measure determinants of HIV infection, treatment coverage, and risk behaviours among transgender populations, distinct from cis-MSM, will improve understanding of HIV risk and vulnerabilities among TGP and support improved programmes.

Trends in HIV prevalence among young people in generalised epidemics: implications for monitoring the HIV epidemic.

BACKGROUND: Countries measure trends in HIV incidence to assess the impact of HIV prevention and treatment programmes. Most countries have approximated trends in HIV incidence through modelled estimates or through trends in HIV prevalence among young people (aged 15-24 years) assuming they have recently become sexually active and have thus only been recently exposed to HIV. METHODS: Trends in HIV incidence are described and results are compared using three proxy measures of incidence: HIV prevalence among young women attending antenatal clinics (ANCs) in 22 countries; HIV prevalence among young male and female nationally representative household survey respondents in 14 countries; and modelled estimates of adult (ages 15-49 years) HIV incidence in 26 countries. The significance of changes in prevalence among ANC attendees and young survey respondents is tested. RESULTS: Among 26 countries, 25 had evidence of some decline in HIV incidence and 15 showed statistically significant declines in either ANC data or survey data. Only in Mozambique did the direction of the trend in young ANC attendees differ from modelled adult incidence, and in Mali and Zambia trends among young men differed from trends in adult incidence. The magnitude of change differed by method. CONCLUSIONS: Trends in HIV prevalence among young people show encouraging declines. Changes in fertility patterns, HIV-infected children surviving to adulthood, and participation bias could affect future proxy measures of incidence trends.

Analysis of duration of risk behaviour for key populations: a literature review.

BACKGROUND: The objective of this paper is to review literature in order to calculate regional estimates of the average duration of time individuals maintain a specific high-risk behaviour. METHODS: The review targeted the key populations of female sex workers (FSW), male clients of female sex workers (MCFSW), people who inject drugs (injecting drug users (IDU)) and high-risk men who have sex with men (MSM). To be included in the review the study had to provide information on (1) the time a person spent at risk until death or cessation of the risk behaviour, (2) the percentage of the sample who initiated the risk behaviour in less than a year or (3) the mean or median duration of the behaviour from a representative sample. RESULTS: 49 papers were found for the FSW population describing the period of time FSW stay in sex work to be between 2.9 years (Asia) and 12 years (Latin America). Eight papers were found for MCFSW showing the duration of the risk behaviour in this category varying from 4.6 years in Africa to 32 years in Asia. 86 papers were reviewed for the population of IDU showing that the average time a person injects illegal drugs varies from 5.6 years (Africa) to 21 years (South America). No information was found for duration of high-risk behaviour among MSM; instead, the definitions found in the literature for high- and low-risk behaviour among MSM were described. CONCLUSIONS: There is high variability of estimates of duration of high-risk behaviours at regional level. More research is needed to inform models and prevention programmes on the average duration of time individuals maintain a specific high-risk behaviour.

Estimates of peripartum and postnatal mother-to-child transmission probabilities of HIV for use in Spectrum and other population-based models.

BACKGROUND: The Global Plan Towards the Elimination of New HIV Infections among Children and Keeping Their Mothers Alive aims to reduce by 2015 the number of new infections in children, in 22 priority countries, by at least 90% from 2009 levels. Mathematical models, such as Spectrum, are used to estimate national and global trends of the number of infants infected through mother-to-child transmission (MTCT). However, other modelling exercises have also examined MTCT under different settings. MTCT probabilities applied in models to populations that are assumed to receive antiretroviral interventions need to reflect the most current risk estimates. METHODS: The UNAIDS Reference Group on Estimates, Modelling and Projections held a consultation to review data on MTCT probabilities. Published literature, recent conferences and data from personal communications with principle investigators were reviewed. Based on available data, peripartum and postnatal transmission probabilities were estimated for different antiretroviral drug regimens and maternal CD4 levels including for women with incident infection. RESULTS: Incident infections occurring during pregnancy are estimated to be associated with a 30% probability of MTCT; incident infections during breast feeding lead to a 28% probability of postnatal MTCT. The 2010 WHO recommended regimens (Options A or B) are estimated to be associated with a 2% peripartum transmission probability and 0.2% transmission probability per month of breast feeding. Peripartum and postnatal transmission probabilities were lowest for women who were taking antiretroviral therapy before the pregnancy namely 0.5% peripartum and 0.16% per month of breast feeding, respectively. DISCUSSION: These updated probabilities of HIV transmission (applied to Spectrum in April 2011) will be used to estimate new child HIV infections and track progress towards the 2015 targets of the Global Plan.

Use of HIV Recency Assays for HIV Incidence Estimation and Other Surveillance Use Cases: Systematic Review.

BACKGROUND: HIV assays designed to detect recent infection, also known as "recency assays," are often used to estimate HIV incidence in a specific country, region, or subpopulation, alone or as part of recent infection testing algorithms (RITAs). Recently, many countries and organizations have become interested in using recency assays within case surveillance systems and routine HIV testing services to measure other indicators beyond incidence, generally referred to as "non-incidence surveillance use cases." OBJECTIVE: This review aims to identify published evidence that can be used to validate methodological approaches to recency-based incidence estimation and non-incidence use cases. The evidence identified through this review will be used in the forthcoming technical guidance by the World Health Organization (WHO) and United Nations Programme on HIV/AIDS (UNAIDS) on the use of HIV recency assays for identification of epidemic trends, whether for HIV incidence estimation or non-incidence indicators of recency. METHODS: To identify the best methodological and field implementation practices for the use of recency assays to estimate HIV incidence and trends in recent infections for specific populations or geographic areas, we conducted a systematic review of the literature to (1) understand the use of recency testing for surveillance in programmatic and laboratory settings, (2) review methodologies for implementing recency testing for both incidence estimation and non-incidence use cases, and (3) assess the field performance characteristics of commercially available recency assays. RESULTS: Among the 167 documents included in the final review, 91 (54.5%) focused on assay or algorithm performance or methodological descriptions, with high-quality evidence of accurate age- and sex-disaggregated HIV incidence estimation at national or regional levels in general population settings, but not at finer geographic levels for prevention prioritization. The remaining 76 (45.5%) described the field use of incidence assays including field-derived incidence (n=45), non-incidence (n=25), and both incidence and non-incidence use cases (n=6). The field use of incidence assays included integrating RITAs into routine surveillance and assisting with molecular genetic analyses, but evidence was generally weaker or only reported on what was done, without validation data or findings related to effectiveness of using non-incidence indicators calculated through the use of recency assays as a proxy for HIV incidence. CONCLUSIONS: HIV recency assays have been widely validated for estimating HIV incidence in age- and sex-specific populations at national and subnational regional levels; however, there is a lack of evidence validating the accuracy and effectiveness of using recency assays to identify epidemic trends in non-incidence surveillance use cases. More research is needed to validate the use of recency assays within HIV testing services, to ensure findings can be accurately interpreted to guide prioritization of public health programming.