Introduction
Poverty and inequality in wealth and resources are important social determinants of health [
1]. Cash transfers (CTs) have a long history as a social protection policy and government-led CT programmes have been implemented to reduce poverty and vulnerability in many low- and middle-income countries, including more recently in sub-Saharan Africa [
2,
3]. CTs are the direct transfer of money to an eligible person or household. Most CT programmes involve regular rather than one-off payments of varying amounts, often adjusted for other household factors such as number of children. CTs may be unconditional (UCTs) or conditional (CCTs) on meeting specific criteria. They have been demonstrated to have a range of positive impacts on health, nutritional, and educational outcomes [
4]. Recently, interests increased in CTs as a strategy for prevention of HIV and other sexually transmitted infections (STIs) [
5,
6].
CTs can have a range of effects on behaviour relevant for HIV/STI prevention. If CTs are conditional on sexual decisions, including staying free of STIs, CCTs create a price effect by making sexual behaviour associated with STI risks costlier as income is lost when not meeting these conditions [
7]. CCTs also bring the positive effects of safer sexual behaviour closer in time, addressing the discounting of future benefits (staying free of HIV/STIs) compared to present benefits of potentially unsafe behaviour [
7]. Moreover, CTs have an income effect and can address social determinants of HIV/STI infection risks by improving economic positions of individuals and so abilities to engage in safer sexual behaviour. This income effect may be particularly relevant for women who are often unable to negotiate condom use in sexual relationships that are characterised by economic imbalances and may have economic motives to engage in transactional relationships or sex work. Improved incomes may also remove economic barriers to accessing healthcare and HIV/STI prevention methods [
8].
Benefits of CTs for HIV/STI prevention have been examined in randomised controlled trials (RCTs) [
8,
9] and evaluations of national CT programmes [
10‐
14], as summarised in Tables
1 and
2 and with more details provided in Additional file
1. Among school children in South Africa, one RCT (CAPRISA 007) found effects of CTs on HIV herpes simplex virus type 2 (HSV-2) incidence [
15], while the HPTN 068 study did not find such effects [
16], although HPTN 068 found reduced numbers of sexual partners and delayed sexual debut [
17]. Other RCTs also found effects on sexual behaviour [
18,
19], although some of these effects were found to be short-lived [
20] . Similarly, RCTs with CTs conditional on staying STI-free showed effects on STI prevalence but these effects tended to disappear after the end of the studies [
21‐
23]. In addition to purposively designed trials, evaluations of CT programmes in South Africa [
10,
11], Kenya [
13,
14,
24], and Malawi [
12] found effects on sexual behaviour among younger people relevant for HIV/STI prevention, including reductions in transactional and age-disparate relationships and delayed sexual debut.
Table 1
Findings of previous evaluations of the effects of cash transfers on HIV prevention outcomes in sub-Saharan Africa among females
South Africa |
HPTN 068 | | School: 13–20 years | CCT | No effect on HIV or HSV-2 incidence | Reduced sexual debut; fewer partners; no effect multiple partners | Reduced unprotected sex | Reduced IPV; no effect on age-disparate relationships or transactional sex |
CAPRISA 007 | | School: grade 9/10 | CCT | Reduced HSV-2 incidence | Not measured | Not measured | Not measured |
NSP (national) | | 10–18 years | UCT | Not measured | No effect multiple partners | No effect unprotected sex | Reduced age-disparate relationships and transactional sex |
CSG (national) | | 15–16 years | UCT | Not measured | Reduced sexual debut; fewer partners | Not measured | Not measured |
Malawi |
SIHR | | School: 13–22 years | UCT, CCT | Reduced HIV & HSV-2 prevalence | No effect sexual debut, reduced frequency of sex past week | No effect unprotected sex | Reduced age-disparate relationships |
SCT (national) 24-month | | 13–19 years | UCT | Not measured | No effect sexual debut; reduced sex acts b | No effect condom use b | Reduced age-disparate relationships; no effect on transactional sex; reduced IPV |
MIP | | 15+ years | CCT | Not measured | Reduced sex past 9 days | No effect condom use | Net decrease condomless sex |
Zimbabwe |
HSCT (national) 48-month c | | 13–20 years | UCT | Not measured | Increased age at first sex; no effect number of sex acts or partners | Reduced unprotected sex | No effect on transactional sex |
Kenya |
CT-OVC (national) | | 15–25 years | UCT | Not measured | Reduced sexual debut; reduced multiple partners | No effect condom use | No effect on transactional sex |
Tanzania |
RESPECT | | 18–30 years | CCT | Reduced STI prevalence | Reduced multiple partners | No effect condom use | Not measured |
Lesotho |
Lottery | | 18–32 years | CCT | Reduced HIV incidence | Reduced number of partners b | Reduced unprotected sex b | Not measured |
Table 2
Findings of previous evaluations of the effects of cash transfers on HIV prevention outcomes in sub-Saharan Africa among males
South Africa |
CAPRISA 007 | | School: grade 9/10 | CCT | Reduced HSV-2 incidence | Not measured | Not measured | Not measured |
NSP (national) | | 10–18 years | UCT | Not measured | Reduced multiple partners | No effect unprotected sex | No effect on age-disparate relationships or transactional sex |
CSG (national) | | 15–16 years | UCT | Not measured | No effect sexual debut; fewer partners | Not measured | Not measured |
Malawi |
SCT (national) 24-month | | 13–19 years | UCT | Not measured | Reduced sexual debut; reduced sex acts b | No effect condom use b | Not measured |
MIP | | 15+ years | CCT | Not measured | Increased sex past 9 days | Increased condom use | Net increase condomless sex |
Zimbabwe |
HSCT (national) 48-month c | | 13–20 years | UCT | Not measured | Reduced sexual debut; no effect number of sex acts or partners | Reduced unprotected sex | No effect on transactional sex |
Kenya |
CT-OVC (national) | | 15–25 years | UCT | Not measured | Reduced sexual debut; no effect multiple partners | No effect condom use | No effect on transactional sex |
Tanzania |
RESPECT | | 18–30 years | CCT | Reduced STI prevalence | No effect multiple partners | Increase condom use | Not measured |
Lesotho |
Lottery | | 18–32 years | CCT | Reduced HIV incidence | Reduced number of partners b | Reduced unprotected sex b | Not measured |
These evaluations of CTs in trials or national programmes demonstrate that CTs can have effects on sexual behaviour that are associated with reduced risks for HIV/STI infection, although few studies demonstrate effects on biological outcomes. There are further questions regarding the sustainability of the effects of CTs on behaviour and causal pathways of these effects [
26]. Trials on CTs tended to focus on increasing school enrolment [
15,
16,
18], while one study of the impact of a Kenyan UCT programme indicated that observed effects were only partially mediated by increased school enrolment [
27]. A major limitation of studies of CTs is the focus on younger people, particularly young females, with effects among males being less clear. This is particularly relevant in the context of potential adverse effects of CTs in terms of possibly health-damaging behaviours, including risky sex and alcohol, cigarette, and drug consumption, which may be more common among males. While the HPTN 068 trial and two evaluations of South African CT programmes found no such adverse effects [
10,
11,
28], evaluations of CTs in Kenya and Malawi found indications for increased unprotected sex among males receiving CTs [
14,
20], and, in a qualitative study of a pilot CT programme in Johannesburg, participants reported that spending on drugs and alcohol was common among CT recipients and that some males engaged in criminal activities after the trial ended to compensate for the reduced income [
29].
Most evidence for the effectiveness of using CTs for HIV/STI prevention comes from purposively designed trials [
15,
20]. There is limited evidence about whether CT not designed for HIV prevention can have spillover effects (externalities of the intervention) that may be beneficial (e.g. partner reduction or increased condom use) or detrimental for HIV/STI prevention (e.g. increased condomless sex or alcohol use). Such spillover effects may occur when CTs have unintended effects on the individual receiving the CT or among individuals living in a household receiving CTs. Evaluations of national CT programmes consider such unintended spillover effects, but these have only been conducted in a limited number of settings. CT interventions, particularly CCT interventions, are associated with high costs, and the cost-effectiveness of these interventions could be increased – if there are beneficial spillover effects – or decreased. This cost-effectiveness is relevant for questions about the scalability of CT programmes [
30]. Given the continuing interest of policy makers in CT as a social protection policy and for HIV/STI prevention, further evaluations of spillover effects of CTs in different settings are needed urgently.
Poverty and CTs in Zimbabwe
Zimbabwe has experienced considerable economic decline since the late 1990s and increasing proportions of individuals living in poverty [
31,
32]. This economic collapse followed shortly after the peak of one of the largest HIV epidemics in the world, which had considerable impacts on mortality [
33] and led to a rapid increase in the number of children under the age of 18 years orphaned due to AIDS-related deaths of their parents, peaking at 880,000 in the period of 2005 to 2007 [
34]. Rising poverty and food insecurity, particularly in rural areas, and increasing numbers of orphans and vulnerable children (OVC) led to growing interest in CTs as a social protection policy in Zimbabwe. Before rolling out a national CT programme to improve children’s development, a CT intervention was piloted in the Manicaland Cash Transfer Trial (Manicaland Trial), a cluster-randomised controlled trial (cRCT) in Manicaland, eastern Zimbabwe, which evaluated effects of CCTs and UCTs given to households on children’s (2–17 years) birth registration, immunisation, and school attendance [
35].
The Manicaland Trial was terminated after 1 year due to plans to roll-out a national CT programme targeting vulnerable households. This Harmonised Social Cash Transfer (HSCT) programme was started to be implemented by the Ministry of Public Service, Labour and Social Welfare (MPSLSW) in 2011in 10 districts across Zimbabwe [
36]. The HSCT programme involves unconditional monthly transfers of US$10–25. By 2014, 55,509 households were enrolled in 20 districts Zimbabwe [
36]. Despite the long-term goal to cover over 250,000 households in all 65 districts of Zimbabwe, the number of enrolled households nearly halved by 2017 compared to 2014 [
25].
The HSCT programme was evaluated using a non-experimental study design that involved a baseline survey in 2013 and follow-up surveys after 12 and 48 months [
25,
36], reflecting different levels of exposure to the programme. One district in which implementation of the HSCT programme had started was selected in each of the three provinces. Control households were selected from three districts neighbouring the three treatment districts where the HSCT programme was planned to be rolled out at a later stage. These districts were matched on agro-ecological, cultural, and developmental characteristics by MPSLSW experts. The short- and long-term evaluations of the HSCT found no improvements in primary or secondary school enrolment or grade progression [
25,
36]. In the long-term evaluation, among youth aged 13–20 years, a 9% reduction in sexual debut and a 5% reduction in unprotected sex in the past 3 months was found in households receiving CTs, although no effects of CTs on number of sexual acts or sexual partners were found [
25].
Objectives of this study
While the HSCT programme evaluation in Zimbabwe indicated that CTs can have impacts on young people that are likely to be beneficial for HIV prevention, the non-experimental evaluation approach has limitations and trends in outcome measures in control and treatment clusters may not be comparable (for example, the evaluations found significant differences in school attendance, expenditure on healthcare, and perceptions about HIV infection risks in the treatment and control households at baseline [
36]). Therefore, such an approach is inferior to experimental or quasi-experimental evaluation methods. Moreover, the HSCT evaluation suffers from limitations similar to other CT evaluations, focusing on sexual behaviour among young people and excluding older individuals.
Given that the Manicaland Cash Transfer Trial was conducted in the same communities as the Manicaland General-Population Cohort (Manicaland Cohort), a long-term open-cohort study, additional information was collected on members of households receiving CTs through ongoing longitudinal surveys of the population. This provided a unique opportunity for evaluating spillover effects of a CT intervention not designed for HIV prevention. This study expands the literature on CTs for HIV prevention by focusing on:
1
Spillover effects on outcomes relevant for HIV/STI prevention, including direct effects on sexual behaviour and on possible mediating factors such as mental health, schooling, and use of alcohol and drugs; and
2
Whether effects differed between sub-groups, including younger and older people, males and females, and individuals living in male- and female-headed households.
Discussion
This study of largely rural communities in eastern Zimbabwe affected by a generalised HIV epidemic found evidence that a CT intervention without HIV/STI-specific objectives had spillover effects relevant for HIV/STI prevention. These included lower recent sexual activity among young people, possibly increased condom use, and increased multiple partnerships among young males, while there were no effects on sexual debut or effects on recent sexual activity among older people. Especially among young men, school enrolment was increased. There was no increased alcohol, cigarette, or drug consumption in households receiving CTs.
CTs and sexual behaviour
This study found no effects on sexual debut among males and females aged 15–20 years, while the HSCT programme evaluation in Zimbabwe found a 13PP reduction in sexual debut among those aged 13–20 years after 12-month [
36] (−9PP after 48 months [
25]). In the Manicaland Trial, levels of sexual debut were low (4.49% among control males; 15.9% among females), compared to 17% in the treatment and 28% in the control group after 12 months in the HSCT evaluation [
36]. Similarly, other CT programmes that reduced sexual debut (in Kenya [
13] and Malawi [
12]) had higher levels of sexual debut compared to Manicaland. Therefore, reductions in sexual debut due to CTs may depend on baseline levels of sexual debut. On the other hand, this study found reductions in any recent sexual activity among sexually active young people (15–29 years), similar to other CT interventions [
11,
12,
17,
18]. The HSCT evaluation found no effect on numbers of sex acts in the past 3 months [
25,
36], but measures may not be comparable.
Young males living in CT-receiving households were more likely to report multiple partners in the past year. The HSCT evaluation found that, after 48 months, males (13–20 years) in CT-receiving households had, on average, 1.67 sexual partners in the past 12 months compared to 1.23 in control households [
25]. CT evaluations in Tanzania [
21] and Malawi [
12] found no effects on multiple partnerships among young males while reductions were found in Kenya [
13,
14] and South Africa [
10], although multiple partnerships were more common in South Africa (30% among those aged 15–17 years vs. 18% in the Manicaland young male control group). In the Manicaland Trial, CT could have led to economic empowerment of young men to attract more sexual partners, but reasons for the increase of multiple partnerships are unclear. However, it underscores the importance of monitoring possible adverse effects of CTs.
Compared to the synthetic comparison group, CTs in the Manicaland Trial were found to increase condom use during last sex among younger and older women and among older men. Similarly, significant reductions in unprotected sex in the past 3 months among CT recipients were found among young males and females after 48 months in the HSCT evaluation [
25] and schoolgirls in the HPTN 068 trial [
16], while other CT evaluations did not find effects on condom use [
10,
12,
13]. Again, these contrasting effects could be the result of different baseline levels in condom use.
CTs and school enrolment
The 10PP increase in school enrolment among young males in households receiving CTs was similarly found CT evaluations in Kenya [
27] and Malawi [
12]. Similar to the current study, the study in Kenya did not find effects on school enrolment among females [
27], while the evaluation in Malawi similar effects among males and females. In the SIHR study, CT-receiving schoolgirls enrolled in school at baseline were more likely to be still enrolled in school at follow-up [
18], with CCTs having stronger effects, similar to findings of the current study and the original Manicaland Trial evaluation [
35]. A previous analysis of the Manicaland Trial found that CCTs were particularly effective at replacing child labour with school attendance [
59]. High acceptance of the conditions in the CCT group was found in qualitative studies of the Trial [
60,
61], which were seen as a way to promote good parenting and build social accountability, possibly explaining stronger effects of the CCT intervention.
The HSCT evaluation in Zimbabwe did not find effects of CTs on primary or secondary school enrolment or grade progression after 12 or 48 months [
25,
36], with similar levels of baseline school enrolment as in the Manicaland Study. The HSCT programme was found to have negative impacts on receiving secondary school scholarships under the Basic Education Assistance Module (BEAM) [
25], thus offsetting any positive effects of receiving CTs. Differences between the Manicaland Trial and HSCT programme illustrate that large-scale programmes may not have the same effects as trials which are implemented under more controlled conditions. Specifically, coordination was lacking between the separate ministries implementing the HSCT and BEAM programmes [
25].
Increased school enrolment due to CTs may partially explain lower reporting of any recent sexual activity among young people. School enrolment was more strongly increased among males and among those receiving CCTs, among which reductions in sexual activity was stronger. Although studies tend to focus on females, school attendance has been shown to reduce HIV risks through delayed sexual debut and changes in sexual behaviour [
44,
45], and a Kenyan CT programme evaluation found school enrolment to mediate changing sexual behaviour [
27]. Mediating effects of school enrolment may also explain why fewer and weaker effects of CTs were observed among older people (who may also be more likely to be in more stable sexual relationships). The short Trial duration and focus on improving school enrolment may have not generated a sufficient income effect that could have impacted outcomes among older people. However, given that young females in households receiving CTs in the Trial showed reductions in any recent sexual activity and increased condom use while effects on school enrolment were limited, other factors are likely to mediate between CTs and sexual behaviour, which has been similarly found in Kenya [
27] and South Africa [
16].
CTs and mental health
The Manicaland Trial did not find effects of CTs on proportions of males or females classified as psychologically distressed, similar to evaluations of the HSCT programme in Zimbabwe which found no effects on proportions classified as depressed [
25,
36]. Nevertheless, there were indications that CTs in Manicaland shifted distributions of reported symptoms of psychological distress and a qualitative study of the Trial found that children and guardians in households receiving CTs reported reduced levels of stress and anxiety [
61]. A previous analysis of the study population found links between psychological distress and potentially risky sexual behaviour [
46], so improved mental health may have contributed to reduced recent sexual activity, although reverse causality is possible. Similarly, the Kenyan CT evaluation found a mediating role of mental health [
27]. Among schoolgirls in a CT programme in Malawi, which split varying amounts of CTs between schoolgirls and guardians, psychological distress was reduced by 14PP by UCTs and 6PP by CCTs [
62]. Limited improvement in mental health in the CCT group was largely due to increased distress among schoolgirls whose parents received larger cash amounts, suggesting that CTs can cause distress when they become an important source of household income and depend on the adolescents’ behaviour. Increasing psychological distress among some individuals may contribute to lack of average effects identified in this study, although similarly weak effects were found in the UCT and CCT interventions.
Alcohol, cigarette, and drug consumption
Similar to evaluations of the HSCT programme in Zimbabwe as well as the HPTN 068 trial and national programmes in South Africa [
10,
14,
28], this study did not find evidence that individuals living in CT households increased alcohol, cigarette, or drug consumption; in fact, these behaviours may be reduced by CTs, which was also indicated by the HSCT evaluation [
25]. While qualitative studies of the Trial reported that older men were considered to misappropriate CTs [
60,
61], including for alcohol, this study indicates that, if anything, this did not occur on a large scale.
Effects by sex of head of household
Given that CTs were distributed to household heads in the Manicaland Trial, the distribution of cash within households likely influenced whether individuals’ behaviours changed, and this study found different effects of CTs in households headed by males or females. CT increased school enrolment among males more strongly in male-headed households, and female school enrolment was only increased in female-headed households. Given that caring for an orphan was one Trial eligibility criteria, a large proportion of young people included in the analysis were orphans (both parents were alive for about one-third of those aged under 18). Previous mixed-methods studies in the study population found that children whose fathers died were more likely to live in female-headed households with the mother or other female relatives while children whose mothers died were less likely to live with the surviving father [
63]. Moreover, living with the surviving mother or another female relative was found to be beneficial for primary school completion, particularly for girls, possibly due to reduced gender bias in resource allocation in households. Living with surviving fathers had detrimental effects on maternal orphans’ school completion, particularly for girls. This may explain why there was no increased school enrolment due to CTs among females living in male-headed households and why there was an effect on males in male- and female-headed households but this was stronger in male-headed households. This advantage of living in female-headed households is also reflected in generally higher levels of school enrolment and the gender bias in resource allocation is reflected in higher male school enrolment regardless of household type. This indicates that household characteristics are important as to whether CTs have effects. This is further illustrated by effects on any recent sexual activity, which was reduced among young males and females only in male-headed households receiving CTs, which had higher baseline sexual activity levels for both sexes, possibly because orphans living in male-headed households are less likely to live with the father [
63].
Limitations
Limited sample size resulted in high uncertainty around estimates, particularly in sub-analyses. Effective sample sizes and statistical power to detect effects of CTs may have been further reduced by the fact that the Manicaland Cohort data were collected over 20 months, so some study sites were covered early during the Manicaland Trial and study participants may have not received a large enough CT ‘dose’ for measurable impacts on outcomes. However, analyses of the synthetic comparison groups, which had larger sample sizes, largely confirmed results of analyses of the original Trial sample, although there may be fundamental differences between those who participated in the Trial and those who did not (who became part of the synthetic comparison group) – despite good balance of the original treatment and synthetic comparison groups in terms of socio-demographic and economic characteristics. These differences may not be captured in the data, particularly as community groups guided the selection of the most disadvantaged households. Therefore, results that differed markedly between original and synthetic comparison group analyses, including for condom use, need to be considered with caution. The fact that the distribution of CTs within households was unknown likely further introduced imprecision in estimates as individuals may have been included in analyses that did not benefitted from CTs given to households. This means that CT effects that were identified in the study are likely to be underestimates. Additionally, with analyses of the original and synthetic control groups, a large number of statistical tests have been conducted, so some apparent effects may have been found by chance. Nevertheless, there is a general consistency between results and prior hypotheses, often supported by results across several comparisons, providing confidence into the conclusions drawn from the analyses.
A further limitation was that data on measures were taken from the Manicaland Cohort that were not designed for analysing the Trial. For example, the survey question for multiple partnerships asked about the number of partners in the past 12 months, which may include a period before the Trial started. However, while this may make it more difficult to identify effects of CTs (committing type II statistical errors), these limitations apply equally to treatment and control groups, thus CT effects identified in this study are unlikely to be biased. Moreover, this study relied on potentially biased self-reporting – despite using informal confidential voting methods to reduce social desirability bias [
64] – but these biases are unlikely to differ between Trial groups, so differences between groups is unlikely the result of differential reporting. The design of this analysis is also likely to have reduced reporting bias as outcome data was collected in the Manicaland Cohort independently from the Manicaland Trial, unlike other CT trials that tend to be unblinded and thus more prone to reporting bias.
As only one measurement of each outcome was available from the Manicaland Cohort data, baseline balance between Trial groups could not be analysed. However, there was a good balance between groups in terms of characteristics unlikely to change within short time periods and analyses controlled for age and socio-economic status. Lack of baseline measures further prevented analyses of temporal changes in study outcomes in control areas. Individuals in Trial control households received fertilisers and seeds, so a general socio-economic improvement may have made it more difficult to identify differences between Trial groups. The Trial was also implemented during a period of economic recovery, which has been found to have affected sexual behaviour of the study population, including increases in multiple partnerships [
65]. However, these broader economic trends impacted treatment and control groups and are unlikely to bias comparisons between groups.
Selection bias when combining the Trial and Cohort data could have been introduced if there were differences between Trial participants linked to the Cohort and those not linked, and these patterns differed between treatment and control groups. However, systematic differences between those included in this analysis and those not were similar between Trial groups, suggesting no bias was introduced at this stage. The systematic differences between those linked to the Cohort and those not may be because, for the baseline Trial survey, heads of households provided data for everyone living in households. This may have inflated numbers of young people listed as living in the households compared to numbers of people found during the Cohort survey, leading to artificial differences in age structures.
Conclusions
This study, using an innovative evaluation approach of combining data sources, demonstrates that a CT intervention aiming to increase educational and health outcomes among children had spillover effects relevant for HIV/STI prevention. These include positive externalities further supporting CT as a social protection policy, including increased school enrolment, reduced sexual activity, and more condom use, and results are likely to be generalisable to other CT interventions in rural sub-Saharan Africa that target socio-economically disadvantaged households, particularly as the Trial involved different study site types [
66]. Nevertheless, effects of CTs may depend on context and baseline levels, e.g. of school enrolment, and Trial results may not be replicated in large national programmes. CT programmes are costly but the diversity in outcomes of structural interventions is often not captured in economic evaluations [
67]. Economic evaluation modelling suggests that considering only HIV infections averted as the outcome in cost-effectiveness analyses may lead to suboptimal resource allocation decisions compared to cost-benefit analyses accounting for other health and educational outcomes [
68]. Such a cross-sector evaluations of CT programmes, as promoted by UNICEF [
69], is also required to detect negative externalities such as increased multiple sexual partnerships among young men living in CT-receiving households in the Manicaland Trial. This and other results of this study demonstrate that CTs may have differential effects on different population groups. Gender-specific effects are not commonly considered and effects of CTs on males are less well-understood than for females. Different effects by type of households found in this study suggest possibilities to target CTs to specific households. For example, female-headed households may be targeted to maximise effects on young women. Questions remain regarding the pathways through which CTs influence behaviour and the sustainability of the effects, but this study adds to the growing body of literature that suggest that CT can have a broad range of beneficial effects for development, addressing structural drivers of HIV infection.
Acknowledgements
We are thankful to everyone who has been involved in the Manicaland Cash Transfer Trial and the Manicaland General-Population Cohort, including those involved in planning, implementation, data collection and processing, and, particularly, the study participants. Part of this work has been presented at the 10th International AIDS Society Conference on HIV Science (IAS 2019), Mexico City, Mexico, 21-24 July 2019.
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