Imperial College London


Faculty of MedicineSchool of Public Health

Professor in Demography and Behavioural Science



+44 (0)20 7594 3279s.gregson




LG27Praed StreetSt Mary's Campus





Publication Type

207 results found

Schaefer R, Gregson S, Benedikt C, Widespread changes in sexual behaviour in eastern and southern Africa: Challenges to achieving global HIV targets? Longitudinal analyses of nationally representative surveys, Journal of the International AIDS Society, ISSN: 1758-2652

Introduction: Sexual behaviour change contributed to reductions in HIV incidence in eastern and southern Africa between 1990 and 2010. More recently, there are indications that non-regular partnerships have increased. However, the effect of these increases on population-level risks for HIV and other sexually transmitted infections could have been reduced by simultaneous increases in condom use. We describe recent trends in sexual behaviour and condom use within the region and assess their combined effects on population levels of sexual risk.Methods: Nationally representative Demographic and Health Survey data on sexually active males and females (15-49 years) were used for 11 eastern and southern African countries (≥3 surveys for each country; 1999-2016) to describe trends in sexual behaviour (multiple, non-regular, and casual sexual partnerships; condom use; age at first sex). Logistic regressions tested for statistical significance of changes. Analyses were stratified by sex.Results: Recent increases in multiple, non-regular, and/or casual partnerships can be found for males in ten countries and, for females, in nine countries; five countries exhibited recent decreases in age of sexual debut. Reduction in sex without condoms with non-regular partners was observed in six countries for males and eight for females. Changes in the proportion of the overall population reporting condomless sex with non-regular partners varied between countries, with declines in six countries and increases in three.Conclusions: Extensive change in sexual behaviour occurred across eastern and southern Africa during the period of scale-up of antiretroviral therapy programmes. This includes increasing multiple and non-regular partnerships, but their potential effects on population-level sexual risks were often offset by parallel increases in condom use. Strengthening condom programmes and reintegrating communication about behavioural dimensions into combination prevention programmes coul


Moorhouse L, Schaefer R, Thomas R, Nyamukapa C, Skovdal M, Hallett T, Gregson Set al., Application of the HIV prevention cascade to identify, develop,and evaluate interventions to improve use of prevention methods:Examples from a study in east Zimbabwe, Journal of the International AIDS Society, ISSN: 1758-2652

Introduction: The HIV prevention cascade could be used in developing interventions to strengthen implementation of efficacious HIV prevention methods but its practical utility needs to be demonstrated. We propose a standardised approach to using the cascade to guide identification and evaluation of interventions and demonstrate its feasibility through a project to develop interventions to improve use of HIV prevention methods by adolescent girls and young women (AGYW) and potential male partners in east Zimbabwe.Discussion: We propose a six-step approach to using a published generic HIV prevention cascade formulation to develop interventions to increase motivation to use, access to and effective use of an HIV prevention method. The six steps are: (1) measure the HIV prevention cascade for the chosen population and method; (2) identify gaps in the cascade; (3) identify explanatory factors (barriers) contributing to observed gaps; (4) review literature to identify relevant theoretical frameworks and interventions; (5) tailor interventions to the local context; and (6) implement and evaluate the interventions using the cascade steps and explanatory factors as outcome indicators in the evaluation design. In the Zimbabwe example, steps 1-5 aided development of four interventions to overcome barriers to effective use of PrEP in AGYW (15-24 years) and VMMC in male partners (15-29). For young men, prevention cascade analyses identified gaps in motivation and access (due to transport costs/lost income) as barriers to VMMC uptake, so an intervention was designed including financial incentives and an education session. For AGYW, gaps in motivation (particularly lack of risk perception) and access were identified as barriers to PrEP uptake: an interactive counselling game was developed addressing these barriers. A text messaging intervention was developed to improve adherence to PrEP among AGYW, addressing reasons underlying lack of effective PrEP use through improving the capa


Skovdal M, Ssekubugu R, Nyamukapa C, Seeley J, Renju J, Wamoyi J, Moshabela M, Ondenge K, Wringe A, Gregson S, Zaba Bet al., 2019, The rebellious man: Next-of-kin accounts of the death of a male relative on antiretroviral therapy in sub-Saharan Africa., Glob Public Health, Pages: 1-12

The HIV response is hampered by many obstacles to progression along the HIV care cascade, with men, in particular, experiencing different forms of disruption. One group of men, whose stories remain untold, are those who have succumbed to HIV-related illness. In this paper, we explore how next-of-kin account for the death of a male relative. We conducted 26 qualitative after-death interviews with family members of male PLHIV who had recently died from HIV in health and demographic surveillance sites in Malawi, Tanzania, Kenya, Uganda, Zimbabwe and South Africa. The next-of-kin expressed frustration about the defiance of their male relative to disclose his HIV status and ask for support, and attributed this to shame, fear and a lack of self-acceptance of HIV diagnosis. Next-of-kin painted a picture of their male relative as rebellious. Some claimed that their deceased relative deliberately ignored instructions received by the health worker. Others described their male relatives as unable to maintain caring relationships that would avail day-to-day treatment partners, and give purpose to their lives. Through these accounts, next-of-kin vocalised the perceived rebellious behaviour of these men, and in the process of doing so neutralised their responsibility for the premature death of their relative.


Schaefer R, Gregson S, Fearon E, Hensen B, Hallett T, Hargreaves JRet al., 2019, HIV prevention cascades: A unifying framework to replicate the successes of treatment cascades, The Lancet HIV, Vol: 6, ISSN: 2405-4704

Many countries are off track to meet targets for reduction of new HIV infections. HIV prevention cascades have been proposed to assist in the implementation and monitoring of HIV prevention programmes by identifying gaps in the steps required for effective use of prevention methods, similar to HIV treatment cascades. However, absence of a unifying framework impedes widespread use of prevention cascades. Building on a series of consultations, we propose an HIV prevention cascade that consists of three key domains of motivation, access, and effective use in a priority population. This three step cascade can be used for routine monitoring and advocacy, particularly by attaching 90-90-90-style targets. Further characterisation of reasons for gaps across motivation, access, or effective use allows for a comprehensive framework that guides identification of relevant responses and platforms for interventions. Linkage of the prevention cascade, reasons for gaps, and interventions reconciles the different requirements of prevention cascades, providing a unifying framework.


Schaefer R, Thomas R, Nyamukapa C, Maswera R, Kadzura N, Gregson Set al., 2018, Accuracy of HIV risk perception in east Zimbabwe 2003-2013, AIDS and Behavior, ISSN: 1090-7165

Risk perception for HIV infection is an important determinant for engaging in HIV prevention behaviour. We investigate the degree to which HIV risk perception is accurate, i.e. corresponds to actual HIV infection risks, in a general-population open-cohort study in Zimbabwe (2003–2013) including 7201 individuals over 31,326 person-years. Risk perception for future infection (no/yes) at the beginning of periods between two surveys was associated with increased risk of HIV infection (Cox regression hazard ratio = 1.38 [1.07–1.79], adjusting for socio-demographic characteristics, sexual behaviour, and partner behaviour). The association was stronger among older people (25+ years). This suggests that HIV risk perception can be accurate but the higher HIV incidence (1.27 per 100 person-years) illustrates that individuals may face barriers to HIV prevention behaviour even when they perceive their risks. Gaps in risk perception are underlined by the high incidence among those not perceiving a risk (0.96%), low risk perception even among those reporting potentially risky sexual behaviour, and, particularly, lack of accuracy of risk perception among young people. Innovative interventions are needed to improve accuracy of risk perception but barriers to HIV prevention behaviours need to be addressed too, which may relate to the partner, community, or structural factors.


Tlhajoane M, Masoka T, Mpandaguta E, Rhead R, Church K, Wringe A, Kadzura N, Arinaminpathy N, Nyamukapa C, Schur N, Mugurungi O, Skovdal M, Eaton J, Gregson Set al., 2018, A longitudinal review of national HIV policy and progress made in health facility implementation in eastern Zimbabwe, Health Research Policy and Systems, Vol: 16, ISSN: 1478-4505

BackgroundIn recent years, WHO has made major changes to its guidance on the provision of HIV care and treatment services. We conducted a longitudinal study from 2013 to 2015 to establish how these changes have been translated into national policy in Zimbabwe and to measure progress in implementation within local health facilities.MethodsNational HIV programme policy guidelines published between 2003 and 2013 (n = 9) and 2014 and 2015 (n = 5) were reviewed to assess adoption of WHO recommendations on HIV testing services, prevention of mother-to-child transmission (PMTCT) of HIV, and provision of antiretroviral therapy (ART). Changes in local implementation of these policies over time were measured in two rounds of a survey conducted at 36 health facilities in Eastern Zimbabwe in 2013 and 2015.ResultsHigh levels of adoption of WHO guidance into national policy were recorded, including adoption of new recommendations made in 2013–2015 to introduce PMTCT Option B+ and to increase the threshold for ART initiation from CD4 ≤ 350 cells/mm3 to ≤ 500 cells/mm3. New strategies to implement national HIV policies were introduced such as the decentralisation of ART services from hospitals to clinics and task-shifting of care from doctors to nurses. The proportions of health facilities offering free HIV testing and counselling, PMTCT (including Option B+) and ART services increased substantially from 2013 to 2015, despite reductions in numbers of health workers. Provision of provider-initiated HIV testing remained consistently high. At least one test-kit stock-out in the prior year was reported in most facilities (2013: 69%; 2015: 61%; p = 0.44). Stock-outs of first-line ART and prophylactic drugs for opportunistic infections remained low. Repeat testing for HIV-negative individuals within 3 months decreased (2013: 97%; 2015: 72%; p = 0.01). Laboratory testing remained low across both surve


Garnett GP, Krishnaratne S, Harris KL, Hallett TB, Santos M, Enstone JE, Hensen B, Dallabetta G, Revill P, Gregson SAJ, Hargreaves JRet al., 2018, Cost-Effectiveness of Interventions to Prevent HIV Acquisition, World Bank Discussion Papers, ISSN: 0259-210X

Because of the severe health consequences of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and the costs of lifelong treatment, inexpensive and effective HIV prevention is bound to be cost-effective. But what constitutes HIV prevention, and can it be affordable and effective? The use of condoms that cost a few cents and prevent a young adult from acquiring a chronic and fatal disease will, over time, be cost saving. Avoiding sex with someone who is infected with HIV/AIDS will be even more so. What can be done to get people to use condoms? What can be done to facilitate the avoidance of risky sexual encounters? Additional efficacious biomedical tools have become available, but similar questions persist: What can be done to get young women at risk to use oral truvada effectively as preexposure prophylaxis (PrEP) and to get young men at risk to be circumcised? The answers to these questions will determine what packages of prevention are essential, how much prevention programs should cost, and how cost-effective they can be. This chapter reviews current evidence about the efficacy, effectiveness, and costs of HIV/AIDS prevention products, programs, and approaches.


Rhead R, Skovdal M, Takaruza A, Maswera R, Nyamukapa C, Gregson Set al., The multidimensionality of masculine norms in east Zimbabwe: implications for HIV prevention, testing and treatment, AIDS, ISSN: 0269-9370

Background: Research and intervention studies suggest that men face challenges in using HIV services in sub-Saharan Africa. To address these challenges, quantitative measurements are needed to establish the individual-level determinants of masculine norms and their implications for HIV prevention and treatment programmes. Methods: Survey questions for four masculine norms identified in qualitative research were included in a general-population survey of 3116 men in east Zimbabwe, 2012-2013. Two sets of regression analyses were conducted in an SEM framework to examine: 1) which socio-demographic characteristics were associated with high scores on each masculinity factor; and 2) how high scores on these masculinity factors differed in their associations with sexual risk behaviour and use of HIV services. Findings: Socio-demographic characteristics associated with high factor scores differed between masculine norms. In HIV-negative men, more men with scores exceeding one standard deviation above the mean (high scorers) for Anti-femininity than men with scores under one standard deviation below the mean (low scorers) took steps to avoid infection (61% versus 54%, p<0.01). Fewer high than low scorers on Social status reported a recent HIV test (69% versus 74%, p=0.04). In HIV-positive men, more high scorers on Sex drive had been diagnosed (85% versus 61%, p=0.02), were on antiretroviral treatment (91% versus 62%, p=0.04), and were in AIDS groups (77% versus 46% p=0.03).Conclusions: HIV treatment, prevention programmes looking to engage men must consider the multi-dimensionality of masculine norms. The scale developed in this study is robust and can be used by other large multi-purpose surveys to examine masculine social norms.


Skovdal M, Maswera R, Kadzura N, Nyamukapa C, Rhead R, Wringe A, Gregson Set al., 2018, Parental obligations, care and HIV treatment: How care for others motivates self-care in Zimbabwe, Journal of Health Psychology, ISSN: 1359-1053

This article examines how parental obligations of care intersect with HIV treatment-seeking behaviours and retention. It draws on qualitative data from eastern Zimbabwe, produced from 65 interviews. Drawing on theories of practice and care ethics, our analysis revealed that norms of parental obligation and care acted as key motivators for ongoing engagement with HIV services and treatment. Parents' attentiveness to the future needs of their children ( caring about), and sense of obligation ( taking care of) and improved ability to care ( caregiving) following treatment initiation, emerged as central to understanding their drive for self-care and engagement with HIV services.


Tlhajoane M, Eaton JW, Takaruza A, Rhead R, Maswera R, Schur N, Sherr L, Nyamukapa C, Gregson Set al., 2018, Prevalence and associations of psychological distress, HIV infection and HIV care service utilization in East Zimbabwe, AIDS and Behavior, Vol: 22, Pages: 1485-1495, ISSN: 1090-7165

The correlation between mental health and sexual risk behaviours for HIV infection remains largely unknown in low and middle income settings. The present study determined the prevalence of psychological distress (PD) in a sub-Saharan African population with a generalized HIV epidemic, and investigated associations with HIV acquisition risk and uptake of HIV services using data from a cross-sectional survey of 13,252 adults. PD was measured using the Shona Symptom Questionnaire. Logistic regression was used to measure associations between PD and hypothesized covariates. The prevalence of PD was 4.5% (95% CI 3.9-5.1%) among men, and 12.9% (95% CI 12.2-13.6%) among women. PD was associated with sexual risk behaviours for HIV infection and HIV-infected individuals were more likely to suffer from PD. Amongst those initiated on anti-retroviral therapy, individuals with PD were less likely to adhere to treatment (91 vs. 96%; age- and site-type-adjusted odds ratio = 0.38; 95% CI 0.15, 0.99). Integrated HIV and mental health services may enhance HIV care and treatment outcomes in high HIV-prevalence populations in sub-Saharan Africa.


Smit M, Olney J, Ford NP, Vitoria M, Gregson S, Vassall A, Hallett TBet al., 2018, The growing burden of non-communicable disease among persons living with HIV in Zimbabwe, AIDS, Vol: 32, Pages: 773-782, ISSN: 0269-9370

Objectives:We aim to characterize the future noncommunicable disease (NCD)burden in Zimbabwe to identify future health system priorities.Methods:We developed an individual-based multidisease model for Zimbabwe,simulating births, deaths, infection with HIV and progression and key NCD [asthma,chronic kidney disease (CKD), depression, diabetes, hypertension, stroke, breast,cervical, colorectal, liver, oesophageal, prostate and all other cancers]. The modelwas parameterized using national and regional surveillance and epidemiological data.Demographic and NCD burden projections were generated for 2015 to 2035.Results:The model predicts that mean age of PLHIV will increase from 31 to 45 yearsbetween 2015 and 2035 (compared with 20 –26 in uninfected individuals). Conse-quently, the proportion suffering from at least one key NCD in 2035 will increase by26% in PLHIV and 6% in uninfected. Adult PLHIV will be twice as likely to suffer from atleast one key NCD in 2035 compared with uninfected adults; with 15.2% of all keyNCDs diagnosed in adult PLHIV, whereas contributing only 5% of the Zimbabweanpopulation. The most prevalent NCDs will be hypertension, CKD, depression andcancers. This demographic and disease shift in PLHIV is mainly because of reductions inincidence and the success of ART scale-up leading to longer life expectancy, and to alesser extent, the cumulative exposure to HIV and ART.Conclusion:NCD services will need to be expanded in Zimbabwe. They will need tobe integrated into HIV care programmes, although the growing NCD burden amongstuninfected individuals presenting opportunities for additional services developedwithin HIV care to benefit HIV-negative persons.


Rhead R, Elmes J, Otobo E, Nhongo K, Takaruza A, White P, Nyamukapa C, Gregson Set al., 2018, Do female sex workers have lower uptake of HIV treatment services than non-sex-workers? A cross-sectional study from East Zimbabwe, BMJ Open, Vol: 8, ISSN: 2044-6055

Objective Globally, HIV disproportionately affects female sex workers (FSWs) yet HIV treatment coverage is suboptimal. To improve uptake of HIV services by FSWs, it is important to identify potential inequalities in access and use of care and their determinants. Our aim is to investigate HIV treatment cascades for FSWs and non-sex workers (NSWs) in Manicaland province, Zimbabwe, and to examine the socio-demographic characteristics and intermediate determinants that might explain differences in service uptake.Methods Data from a household survey conducted in 2009–2011 and a parallel snowball sample survey of FSWs were matched using probability methods to reduce under-reporting of FSWs. HIV treatment cascades were constructed and compared for FSWs (n=174) and NSWs (n=2555). Determinants of service uptake were identified a priori in a theoretical framework and tested using logistic regression.Results HIV prevalence was higher in FSWs than in NSWs (52.6% vs 19.8%; age-adjusted OR (AOR) 4.0; 95% CI 2.9 to 5.5). In HIV-positive women, FSWs were more likely to have been diagnosed (58.2% vs 42.6%; AOR 1.62; 1.02–2.59) and HIV-diagnosed FSWs were more likely to initiate ART (84.9% vs 64.0%; AOR 2.33; 1.03–5.28). No difference was found for antiretroviral treatment (ART) adherence (91.1% vs 90.5%; P=0.9). FSWs’ greater uptake of HIV treatment services became non-significant after adjusting for intermediate factors including HIV knowledge and risk perception, travel time to services, physical and mental health, and recent pregnancy.Conclusion FSWs are more likely to take up testing and treatment services and were closer to achieving optimal outcomes along the cascade compared with NSWs. However, ART coverage was low in all women at the time of the survey. FSWs’ need for, knowledge of and proximity to HIV testing and treatment facilities appear to increase uptake.


Gregson S, Mugurungi O, Eaton J, Takaruza A, Rhead R, Maswera R, Mutsangwa J, Mayini J, Skovdal M, Schaefer R, Hallett T, Sherr L, Munyati S, Mason P, Campbell C, Garnett G, Nyamukapa Cet al., 2017, Documenting and explaining the HIV decline in east Zimbabwe: the Manicaland General Population Cohort, BMJ Open, Vol: 7, ISSN: 2044-6055

Purpose: The Manicaland Cohort was established to provide robust scientific data on HIV prevalence and incidence, patterns of sexual risk behaviour, and the demographic impact of HIV in a sub-Saharan African population subject to a generalised HIV epidemic. The aims were later broadened to include provision of data on the coverage and effectiveness of national HIV control programmes including antiretroviral treatment (ART).Participants: General population open cohort located in 12 sites in Manicaland, east Zimbabwe, representing 4 major socio-economic strata (small towns, agricultural estates, roadside settlements, and subsistence farming areas). 9,109 of 11,453 (79.5%) eligible adults (men 17-54 years; women 15-44 years) were recruited in a phased household census between July 1998 and January 2000. Five rounds of follow-up of the prospective household census and the open cohort were conducted at 2 or 3 year intervals between July 2001 and November 2013. Follow-up rates among surviving residents ranged between 77.0% (over 3 years) and 96.4% (2 years). Findings to date: HIV prevalence was 25.1% at baseline and had a substantial demographic impact with 10-fold higher mortality in HIV-infected adults than in uninfected adults and a reduction in the growth rate in the worst affected areas (towns) from 2.9% to 1.0%pa. HIV infection rates have been highest in young adults with earlier commencement of sexual activity and in those with older sexual partners and larger numbers of lifetime partners. HIV prevalence has since fallen to 15.8% and HIV incidence has also declined from 2.1% (1998-2003) to 0.63% (2009-2013) largely due to reduced sexual risk behaviour. HIV-associated mortality fell substantially after 2009 with increased availability of ART


Pufall E, Eaton JW, Robertson L, Mushati P, Nyamukapa C, Gregson Set al., 2017, Education, substance use, and HIV risk among orphaned adolescents in Eastern Zimbabwe, Vulnerable Children and Youth Studies, Vol: 12, Pages: 360-374, ISSN: 1745-0136

There is a growing interest in education as a means to reduce HIV infection in vulnerable children in sub-Saharan Africa; however, the mechanisms by which education reduces HIV infection remain uncertain. Substance use has been associated with high-risk sexual behaviour and could lie on the causal pathway between education and HIV risk. Therefore, we used multivariable regression to measure associations between: (i) orphanhood and substance use (alcohol, recreational drugs, and smoking), (ii) substance use and sexual risk behaviours, and (iii) school enrolment and substance use, in adolescents aged 15–19 years, in Eastern Zimbabwe. We found substance use to be low overall (6.4%, 3.2%, and 0.9% of males reported alcohol, drug, and cigarette use; <1% of females reported any substance use), but was more common in male maternal and double orphans than non-orphans. Substance use was positively associated with early sexual debut, number of sexual partners, and engaging in transactional sex, while school enrolment was associated with lower substance use in males. We conclude that education may reduce sexual risk behaviours and HIV infection rates among male adolescents in sub-Saharan Africa, in part, by reducing substance abuse.


Schaefer R, Gregson S, Eaton JW, Mugurungi O, Rhead R, Takaruza A, Maswera R, Nyamukapa Cet al., 2017, Age-disparate relationships and HIV incidence in adolescent girls and young women: evidence from a general-population cohort in Zimbabwe, AIDS, Vol: 31, Pages: 1461-1470, ISSN: 0269-9370

Objective: Age-disparate sexual relationships with older men may drive high rates of HIV acquisition in young women in sub-Saharan Africa but evidence is limited. We investigate the association between age-disparate relationships and HIV incidence in Manicaland, Zimbabwe.Design: A general-population open-cohort study (six surveys) (1998-2013).Methods: 3746 young women aged 15-24 years participated in consecutive surveys and were HIV-negative at the beginning of inter-survey periods. Last sexual partner age difference and age-disparate relationships (inter-generational [≥10 years age difference] and intra-generational [5-9 years] versus age-homogeneous [0-4 years]) were tested for associations with HIV incidence in Cox regressions. A proximate determinants framework was used to explore factors possibly explaining variations in the contribution of age-disparate relationships to HIV incidence between populations and over time.Results: 126 HIV infections occurred over 8777 person-years (1.43 per 100 person-years; 95% confidence interval=1.17-1.68). 65% of women reported partner age differences of ≥5 years. Increasing partner age differences were associated with higher HIV incidence (adjusted hazard ratio [aHR]=1.05 [1.01-1.09]). Inter-generational relationships tended to increase HIV incidence (aHR=1.78 [0.96-3.29]) but not intra-generational relationships (aHR=0.91 [0.47-1.76]). Secondary education was associated with reductions in inter-generational relationships (adjusted odds ratio [aOR]=0.49 [0.36-0.68]). Inter-generational relationships were associated with partners having concurrent relationships (aOR=2.59 [1.81-3.70]) which tended to increase HIV incidence (aHR=1.74 [0.96-3.17]). Associations between age-disparity and HIV incidence did not change over time.Conclusions: Sexual relationships with older men expose young women to increased risk of HIV acquisition in Manicaland, which did not change over time, even with introduction of antiretroviral therapy.


Skovdal M, Magutshwa-Zitha S, Campbell C, Nyamukapa C, Gregson Set al., 2017, Getting off on the wrong foot? How community groups in Zimbabwe position themselves for partnerships with external agencies in the HIV response, Globalization and Health, Vol: 13, ISSN: 1744-8603

BackgroundPartnerships are core to global public health responses. The HIV field embraces partnership working, with growing attention given to the benefits of involving community groups in the HIV response. However, little has been done to unpack the social psychological foundation of partnership working between well-resourced organisations and community groups, and how community representations of partnerships and power asymmetries shape the formation of partnerships for global health. We draw on a psychosocial theory of partnerships to examine community group members’ understanding of self and other as they position themselves for partnerships with non-governmental organisations.MethodsThis mixed qualitative methods study was conducted in the Matobo district of Matabeleland South province in Zimbabwe. The study draws on the perspectives of 90 community group members (29 men and 61 women) who participated in a total of 19 individual in-depth interviews and 9 focus group discussions (n = 71). The participants represented an array of different community groups and different levels of experience of working with NGOs. Verbatim transcripts were imported into Atlas.Ti for thematic indexing and analysis.ResultsGroup members felt they played a central role in the HIV response. Accepting there is a limit to what they can do in isolation, they actively sought to position themselves as potential partners for NGOs. Partnerships with NGOs were said to enable community groups to respond more effectively as well as boost their motivation and morale. However, group members were also acutely aware of how they should act and perform if they were to qualify for a partnership. They spoke about how they had to adopt various strategies to become attractive partners and ‘supportable’ – including being active and obedient.ConclusionsMany community groups in Zimbabwe recognise their role in the HIV response and actively navigate representational systems of self and


Mangal TD, UNAIDS Working Group on CD4 Progression and Mortality Amongst HIV Seroconverters including the CASCADE Collaboration in EuroCoord, 2017, Joint estimation of CD4+ cell progression and survival in untreated individuals with HIV-1 infection., AIDS, Vol: 31, Pages: 1073-1082, ISSN: 0269-9370

OBJECTIVE: We compiled the largest dataset of seroconverter cohorts to date from 25 countries across Africa, North America, Europe, and Southeast/East (SE/E) Asia to simultaneously estimate transition rates between CD4 cell stages and death, in antiretroviral therapy (ART)-naive HIV-1-infected individuals. DESIGN: A hidden Markov model incorporating a misclassification matrix was used to represent natural short-term fluctuations and measurement errors in CD4 cell counts. Covariates were included to estimate the transition rates and survival probabilities for each subgroup. RESULTS: The median follow-up time for 16 373 eligible individuals was 4.1 years (interquartile range 1.7-7.1), and the mean age at seroconversion was 31.1 years (SD 8.8). A total of 14 525 individuals had recorded CD4 cell counts pre-ART, 1885 died, and 6947 initiated ART. Median (interquartile range) survival for men aged 20 years at seroconversion was 13.0 (12.4-13.4), 11.6 (10.9-12.3), and 8.3 years (7.9-8.9) in Europe/North America, Africa, and SE/E Asia, respectively. Mortality rates increase with age (hazard ratio 2.22, 95% confidence interval 1.84-2.67 for >45 years compared with <25 years) and vary by region (hazard ratio 2.68, 1.75-4.12 for Africa and 1.88, 1.50-2.35 for Asia compared with Europe/North America). CD4 cell decline was significantly faster in Asian cohorts compared with Europe/North America (hazard ratio 1.45, 1.36-1.54). CONCLUSION: Mortality and CD4 cell progression rates exhibited regional and age-specific differences, with decreased survival in African and SE/E Asian cohorts compared with Europe/North America and in older age groups. This extensive dataset reveals heterogeneities between regions and ages, which should be incorporated into future HIV models.


Eaton JW, Johnson CC, Gregson S, 2017, The cost of not re-testing: HIV misdiagnosis in the ART ‘test-and-offer’ era, Clinical Infectious Diseases, Vol: 65, Pages: 522-525, ISSN: 1537-6591

We compared estimated costs of retesting human immunodeficiency virus (HIV)-positive persons before antiretroviral therapy (ART) initiation to the costs of ART provision to misdiagnosed HIV-negative persons. Savings from averted unnecessary ART costs were greater than retesting costs within 1 year using assumptions representative of HIV testing performance in programmatic settings. Countries should implement re-testing before ART initiation.


Wilson KC, Mhangara M, Dzangare J, Eaton JW, Hallett TB, Mugurungi O, Gregson Set al., 2017, Does nonlocal women's attendance at antenatal clinics distort HIV prevalence surveillance estimates in pregnant women in Zimbabwe?, AIDS, Vol: 31, Pages: S95-S102, ISSN: 0269-9370

Objective: The objective was to assess whether HIV prevalence measured among women attending antenatal clinics (ANCs) are representative of prevalence in the local area, or whether estimates may be biased by some women's choice to attend ANCs away from their residential location. We tested the hypothesis that HIV prevalence in towns and periurban areas is underestimated in ANC sentinel surveillance data in Zimbabwe.Methods: National unlinked anonymous HIV surveillance was conducted at 19 ANCs in Zimbabwe in 2000, 2001, 2002, 2004, 2006, 2009, and 2012. This data was used to compare HIV prevalence and nonlocal attendance levels at ANCs at city, town, periurban, and rural clinics in aggregate and also for individual ANCs.Results: In 2000, HIV prevalence at town ANCs (36.6%, 95% CI 34.4–38.9%) slightly underestimated prevalence among urban women attending these clinics (40.7%, 95% CI 37.6–43.9%). However, there was no distortion in HIV prevalence at either the aggregate clinic location or at individual clinics in more recent surveillance rounds. HIV prevalence was consistently higher in towns and periurban areas than in rural areas. Nonlocal attendance was high at town (26–39%) and periurban (53–95%) ANCs but low at city clinics (<10%). However, rural women attending ANCs in towns and periurban areas had higher HIV prevalence than rural women attending rural clinics, and were younger, more likely to be single, and less likely to be housewives.Conclusions: : In Zimbabwe, HIV prevalence among ANC attendees provides reliable estimates of HIV prevalence in pregnant women in the local area.


Silhol R, Gregson S, Nyamukapa C, Mhangara M, Dzangare J, Gonese E, Eaton JW, Case KK, Mahy M, Stover J, Mugurungi Oet al., 2017, Empirical validation of the UNAIDS Spectrum model for subnational HIV estimates: case-study of children and adults in Manicaland, Zimbabwe, AIDS, Vol: 31, Pages: S41-S50, ISSN: 0269-9370

Background: More cost-effective HIV control may be achieved by targeting geographical areas with high infection rates. The AIDS Impact model of Spectrum – used routinely to produce national HIV estimates – could provide the required subnational estimates but is rarely validated with empirical data, even at a national level.Design: The validity of the Spectrum model estimates were compared to empirical estimates.Methods: Antenatal surveillance and population survey data from a population HIV cohort study in Manicaland, east Zimbabwe, were input into Spectrum 5.441 to create a simulation representative of the cohort population. Model and empirical estimates were compared for key demographic and epidemiological outcomes. Alternative scenarios for data availability were examined and sensitivity analyses were conducted for model assumptions considered important for subnational estimates.Results: Spectrum estimates generally agreed with observed data but HIV incidence estimates were higher than empirical estimates while estimates of early age all-cause adult mortality were lower. Child HIV prevalence estimates matched well with the survey prevalence among children. Estimated paternal orphanhood was lower than empirical estimates. Including observations from earlier in the epidemic did not improve the HIV incidence model fit. Migration had little effect on observed discrepancies - possibly because the model ignores differences in HIV prevalence between migrants and residents.Conclusions: The Spectrum model, using subnational surveillance and population data, provided reasonable subnational estimates although some discrepancies were noted. Differences in HIV prevalence between migrants and residents may need to be captured in the model if applied to subnational epidemics.


Case KK, Gregson S, Mahy M, Ghys PD, Hallett TBet al., 2017, Editorial: methodological developments in the Joint United Nations Programme on HIV/AIDS estimates, AIDS, Vol: 31, Pages: S1-S4, ISSN: 0269-9370

The Joint United Nations Programme on HIV/AIDS (UNAIDS) publishes estimates of the HIV epidemic every year [1]. For 2016, estimates are available for 160 countries representing 98% of the global population. These estimates are produced by countries with guidance from UNAIDS. The methods used in this process continue to evolve over time under the stewardship of the UNAIDS Reference Group on Estimates, Modelling and Projections [2].In 2014, the WHO convened the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER) Working Group with the aim to define and promote good practice in reporting global health estimates [3]. The GATHER Statement is the outcome produced by this group. It defines a list of reporting requirements to allow for the accurate interpretation, and facilitate the appropriate use, of global health estimates [4]. UNAIDS fully endorses and supports the GATHER Statement.The current special supplement, which details the methods used to produce the 2016 UNAIDS estimates, further supports the routine publication of data sources and methods used as part of an open and transparent process. It provides updates of the evolving understanding of the data on which the estimates are based, the methods used to derive the estimates, justification of changes in these methods, and the sources of new data available to inform these modifications. It follows a series of such collections [5–10] which have documented and described the evolving methods used to produce the UNAIDS Global AIDS estimates since 2004.


Sheng B, Marsh K, Slavkovic AB, Gregson S, Eaton JW, Bao Let al., 2017, Statistical models for incorporating data from routine HIV testing of pregnant women at antenatal clinics into HIV/AIDS epidemic estimates, AIDS, Vol: 31, Pages: S87-S94, ISSN: 0269-9370

Objective: HIV prevalence data collected from routine HIV testing of pregnant women at antenatal clinics (ANC-RT) are potentially available from all facilities that offer testing services to pregnant women and can be used to improve estimates of national and subnational HIV prevalence trends. We develop methods to incorporate these new data source into the Joint United Nations Programme on AIDS Estimation and Projection Package in Spectrum 2017.Methods: We develop a new statistical model for incorporating ANC-RT HIV prevalence data, aggregated either to the health facility level (site-level) or regionally (census-level), to estimate HIV prevalence alongside existing sources of HIV prevalence data from ANC unlinked anonymous testing (ANC-UAT) and household-based national population surveys. Synthetic data are generated to understand how the availability of ANC-RT data affects the accuracy of various parameter estimates.Results: We estimate HIV prevalence and additional parameters using both ANC-RT and other existing data. Fitting HIV prevalence using synthetic data generally gives precise estimates of the underlying trend and other parameters. More years of ANC-RT data should improve prevalence estimates. More ANC-RT sites and continuation with existing ANC-UAT sites may improve the estimate of calibration between ANC-UAT and ANC-RT sites.Conclusion: We have proposed methods to incorporate ANC-RT data into Spectrum to obtain more precise estimates of prevalence and other measures of the epidemic. Many assumptions about the accuracy, consistency, and representativeness of ANC-RT prevalence underlie the use of these data for monitoring HIV epidemic trends and should be tested as more data become available from national ANC-RT programs.


Schaefer R, Gregson S, Takaruza A, Rhead R, Masoka T, Schur N, Anderson S-J, Nyamukapa Cet al., 2017, Spatial patterns of HIV prevalence and Service Use in East Zimbabwe: implications for future targeting of interventions, Journal of the International AIDS Society, Vol: 20, ISSN: 1758-2652

Introduction: Focusing resources for HIV control on geographic areas of greatest need in countries with generalised epidemics has been recommended to increase cost-effectiveness. However, socio-economic inequalities between areas of high and low prevalence could raise equity concerns and have been largely overlooked. We describe spatial patterns in HIV prevalence in east Zimbabwe and test for inequalities in accessibility and uptake of HIV services prior to the introduction of spatially-targeted programmes.Methods: 8092 participants in an open-cohort study were geo-located to 110 locations. HIV prevalence and HIV testing and counselling (HTC) uptake were mapped with ordinary kriging. Clusters of high or low HIV prevalence were detected with Kulldorff statistics, and the socio-economic characteristics and sexual risk behaviours of their populations, and levels of local HIV service availability (measured in travel distance) and uptake were compared. Kulldorff statistics were also determined for HTC, antiretroviral therapy (ART), and voluntary medical male circumcision (VMMC) uptake.Results: One large and one small high HIV prevalence cluster (relative risk [RR]=1.78, 95% confidence interval [CI]=1.53–2.07; RR=2.50, 95% CI=2.08–3.01) and one low-prevalence cluster (RR=0.70, 95% CI=0.60–0.82) were detected. The larger high-prevalence cluster was urban with a wealthier population and more high-risk sexual behaviour than outside the cluster. Despite better access to HIV services, there was lower HTC uptake in the high-prevalence cluster (odds ratio [OR] of HTC in past 3 years: OR=0.80, 95% CI=0.66–0.97). The low-prevalence cluster was predominantly rural with a poorer population and longer travel distances to HIV services; however, uptake of HIV services was not reduced.Conclusions: High-prevalence clusters can be identified to which HIV control resources could be targeted. To date, poorer access to HIV services in the poorer low-prevalence areas h


Elmes JAR, Skovdal M, Nhongo K, Ward H, Campbell C, Hallett TB, Nyamukapa C, White PJ, Gregson Set al., 2017, A reconfiguration of the sex trade: How social and structural changes in eastern Zimbabwe left women involved in sex work and transactional sex more vulnerable, PLOS One, Vol: 12, ISSN: 1932-6203

Understanding the dynamic nature of sex work is important for explaining the course of HIV epidemics. While health and development interventions targeting sex workers may alter the dynamics of the sex trade in particular localities, little has been done to explore how large-scale social and structural changes, such as economic recessions–outside of the bounds of organizational intervention–may reconfigure social norms and attitudes with regards to sex work. Zimbabwe’s economic collapse in 2009, following a period (2000–2009) of economic decline, within a declining HIV epidemic, provides a unique opportunity to study community perceptions of the impact of socio-economic upheaval on the sex trade. We conducted focus group discussions with 122 community members in rural eastern Zimbabwe in January-February 2009. Groups were homogeneous by gender and occupation and included female sex workers, married women, and men who frequented bars. The focus groups elicited discussion around changes (comparing contemporaneous circumstances in 2009 to their memories of circumstances in 2000) in the demand for, and supply of, paid sex, and how sex workers and clients adapted to these changes, and with what implications for their health and well-being. Transcripts were thematically analyzed. The analysis revealed how changing economic conditions, combined with an increased awareness and fear of HIV–changing norms and local attitudes toward sex work–had altered the demand for commercial sex. In response, sex work dispersed from the bars into the wider community, requiring female sex workers to employ different tactics to attract clients. Hyperinflation meant that sex workers had to accept new forms of payment, including sex-on-credit and commodities. Further impacting the demand for commercial sex work was a poverty-driven increase in transactional sex. The economic upheaval in Zimbabwe effectively reorganized the market for sex by reducing previousl


Melegaro A, Del Fava E, Poletti P, Merler S, Nyamukapa C, Williams J, Gregson S, Manfredi Pet al., 2017, Social contact structures and time use patterns in the Manicaland Province of Zimbabwe., PLOS One, Vol: 12, ISSN: 1932-6203

BACKGROUND: Patterns of person-to-person contacts relevant for infectious diseases transmission are still poorly quantified in Sub-Saharan Africa (SSA), where socio-demographic structures and behavioral attitudes are expected to be different from those of more developed countries. METHODS AND FINDINGS: We conducted a diary-based survey on daily contacts and time-use of individuals of different ages in one rural and one peri-urban site of Manicaland, Zimbabwe. A total of 2,490 diaries were collected and used to derive age-structured contact matrices, to analyze time spent by individuals in different settings, and to identify the key determinants of individuals' mixing patterns. Overall 10.8 contacts per person/day were reported, with a significant difference between the peri-urban and the rural site (11.6 versus 10.2). A strong age-assortativeness characterized contacts of school-aged children, whereas the high proportion of extended families and the young population age-structure led to a significant intergenerational mixing at older ages. Individuals spent on average 67% of daytime at home, 2% at work, and 9% at school. Active participation in school and work resulted the key drivers of the number of contacts and, similarly, household size, class size, and time spent at work influenced the number of home, school, and work contacts, respectively. We found that the heterogeneous nature of home contacts is critical for an epidemic transmission chain. In particular, our results suggest that, during the initial phase of an epidemic, about 50% of infections are expected to occur among individuals younger than 12 years and less than 20% among individuals older than 35 years. CONCLUSIONS: With the current work, we have gathered data and information on the ways through which individuals in SSA interact, and on the factors that mostly facilitate this interaction. Monitoring these processes is critical to realistically predict the effects of interventions on infectious diseas


Rhead RD, Masimirembwa C, Cooke G, Takaruza A, Nyamukapa C, Gregson Set al., Might ART adherence estimates be improved by combining biomarker and self-report data?, PLOS One, Vol: 11, ISSN: 1932-6203

BackgroundAs we endeavour to examine rates of viral suppression in PLHIV, reliable data on ART adherence are needed to distinguish between the respective contributions of poor adherence and treatment failure on high viral load. Self-reported data are susceptible to response bias and although biomarker data on drug presence and concentration can provide a superior, alternative method of measurement, complications due to drug-drug interactions and genetic variations can cause some inaccuracies. We investigate the feasibility of combining both biomarker and self-report data to produce a potentially more accurate measure of ART adherence.MethodsData were taken from a large general-population survey in the Manicaland province, Zimbabwe, conducted in 2009–2011. HIV-infected adults who had initiated ART (N = 560) provided self-report data on adherence and dried blood spot samples that were analysed for traces of ART medication. A new three-category measure of ART adherence was constructed, based on biomarker data but using self-report data to adjust for cases with abnormally low and high drug concentrations due to possible drug-drug interactions and genetic factors, and was assessed for plausibility using survey data on socio-demographic correlates.Results94.3% (528/560) and 92.7% (519/560) of the sample reported faithful adherence to their medication and had traces of ART medication, respectively. The combined measure estimated good evidence of ART adherence at 69% and excellent evidence of adherence at 53%. The regression analysis results showed plausible patterns of ART adherence by socio-demographic status with men and younger participants being more likely to adhere poorly to medication, and higher socio-economic status individuals and those living in more urban locations being more likely to adhere well.ConclusionBiomarker and self-reported measures of adherence can be combined in a meaningful way to produce a potentially more accurate measure of ART adherence.


Negin J, Gregson S, Eaton JW, Schur N, Takaruza A, Mason P, Nyamukapa Cet al., 2016, Rising levels of HIV infection in older adults in eastern Zimbabwe, PLOS One, Vol: 11, ISSN: 1932-6203

BackgroundWith the scale-up of antiretroviral treatment across Africa, many people are living longer with HIV. Understanding the ageing of the HIV cohort and sexual behaviour among older adults are important for appropriately responding to the changing demographics of people living with HIV.MethodsWe used data from a large population-based open cohort in eastern Zimbabwe to examine HIV prevalence trends and incidence among those aged 45 years and older. Five survey rounds have been completed between 1998 and 2011. Incidence was analysed using midpoint between last negative and first positive HIV test.ResultsAcross the survey rounds, 13,071 individuals were followed for 57,676 person years. While HIV prevalence among people aged 15–44 has fallen across the five rounds, HIV prevalence among those aged 45–54 has increased since the 2006–08 survey round. In the 2009–11 round, HIV prevalence among men aged 45–54 was 23.4% compared to 11.0% among those aged 15–44. HIV positive people aged 45–54 now represent more than 20% of all those living with HIV in Manicaland. Among those aged 45 years and older, there were 85 seroconversions in 11,999 person years for an HIV incidence of 0.708 per 100 person years. Analysis of cohort data and assessment of behavioural risk factors for HIV infection among older people shows significantly lower levels of condom use among older adults and a number of seroconversions past the age of 50.ConclusionsThe cohort of people living with HIV is ageing in Zimbabwe and the behaviour of older adults puts them at risk of HIV infection. Older adults must be included in both HIV prevention and treatment programs.


Garnett G, Hallett T, Gregson S, 2016, HIV Prevention Cascades: Identifying Gaps in the Delivery of HIV Prevention Interventions, Conference on HIV Research for Prevention (HIV R4P), Publisher: Mary Ann Liebert, Pages: 245-245, ISSN: 0889-2229


Marston M, Nakiyingi-Miiro J, Kusemererwa S, Urassa M, Michael D, Nyamukapa C, Gregson S, Zaba B, Eaton JW, ALPHA networket al., 2016, The effects of HIV on fertility by infection duration: evidence from African population cohorts before ART availability: Fertility by duration of HIV infection, AIDS, Vol: 31, Pages: S69-S76, ISSN: 1473-5571

OBJECTIVES: To estimate the relationship between HIV natural history and fertility by duration of infection in East and Southern Africa before the availability of antiretroviral therapy, and assess potential biases in estimates of age-specific sub-fertility when using retrospective birth histories in cross-sectional studies. DESIGN: Pooled analysis of prospective population-based HIV cohort studies in Masaka (Uganda) Kisesa (Tanzania), and Manicaland (Zimbabwe). METHODS: Women aged 15-49 who had ever tested for HIV were included. Analyses were censored at antiretroviral treatment roll out. Fertility rate ratios were calculated to see the relationship of duration of HIV infection on fertility, adjusting for background characteristics. Survivorship and misclassification biases on age-specific subfertility estimates from cross-sectional surveys were estimated by reclassifying person time from the cohort data to simulate cross-sectional surveys and comparing fertility rate ratios to true cohort results. RESULTS: HIV negative and positive women contributed 15,440 births and 86320 person years; and 1,236 births and 11240 thousand person years respectively to the final dataset. Adjusting for age, study site and calendar year, each additional year since HIV sero conversion was associated with a 0.02 (95%CI 0.01-0.03) relative decrease infertility for HIV-positive women. Survivorship and misclassification biases in simulated retrospective birth histories resulted in modest underestimates of sub-fertility by 2-5% for age groups 20-39y. CONCLUSION: Longer duration of infection is associated with greater relative fertility reduction for HIV-positive women. This should be considered when creating estimates for HIV prevalence among pregnant women and PMTCT need over the course of the HIV epidemic and ART scale-up.


Del Fava E, Piccarreta R, Gregson S, Melegaro Aet al., 2016, Transition to parenthood and HIV infection in rural Zimbabwe, PLOS One, Vol: 11, ISSN: 1932-6203

BackgroundThe relationship between the risk of acquiring human immunodeficiency virus (HIV) infection and people’s choices about life course events describing the transition to parenthood–sexual debut, union (in the form of marriage, cohabitation, or long-term relationship), and parenthood–is still unclear. A crucial role in shaping this relationship may be played by the sequence of these events and by their timing. This suggests the opportunity to focus on the life courses in their entirety rather than on the specific events, thus adopting a holistic approach that regards each individual’s life course trajectory as a whole.MethodsWe summarise the individual life courses describing the transition to parenthood using ordered sequences of the three considered events. We aim to (i) investigate the association between the sequences and HIV infection, and (ii) understand how these sequences interact with known mechanisms for HIV transmission, such as the length of sexual exposure and the experience of non-regular sexual partnerships. For this purpose, we use data from a general population cohort study run in Manicaland (Zimbabwe), a Sub-Saharan African area characterised by high HIV prevalence.ResultsFor both genders, individuals who experienced either premarital or delayed childbearing have higher HIV risk compared to individuals following more standard transitions. This can be explained by the interplay of the sequences with known HIV proximate determinants, e.g., a longer exposure to sexual activity and higher rates of premarital sex. Moreover, we found that people in the younger birth cohorts experience more normative and safer sequences.ConclusionsThe shift of younger generations towards more normative transitions to parenthood is a sign of behaviour change that might have contributed to the observed reduction in HIV prevalence in the area. On the other hand, for people with less normative transitions, targeted strategies are essential for HI


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