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Dive into the research topics where Simon Gregson is active.

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Featured researches published by Simon Gregson.


AIDS | 2007

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

Lorraine Sherr; Ben Lopman; Memory Kakowa; Sabada Dube; Godwin Chawira; Constance Nyamukapa; Nicole Oberzaucher; Ide Cremin; Simon Gregson

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


The Lancet | 2012

Technologies for global health

Peter Howitt; Ara Darzi; Guang-Zhong Yang; Hutan Ashrafian; Rifat Atun; James Barlow; Alex Blakemore; Anthony M. J. Bull; Josip Car; Lesong Conteh; Graham S. Cooke; Nathan Ford; Simon Gregson; Karen Kerr; Dominic King; Myutan Kulendran; Robert A. Malkin; Azeem Majeed; Stephen A. Matlin; Robert Merrifield; Hugh A Penfold; Steven D Reid; Peter C. Smith; Molly M. Stevens; Michael R. Templeton; Charles Vincent; Elizabeth Wilson

Institute for Global Health Innovation (L Conteh PhD, Prof A Darzi FRCS, P Howitt MA, K Kerr PhD, Prof S Matlin DSc, R Merrifi eld PhD, Prof G-Z Yang PhD), Centre for Environmental Policy (E Wilson MSc), Centre for Health Policy (D King MRCS, M Kulendran MRCS, Prof P C Smith BA), Department of Bioengineering (Prof A M J Bull PhD, Prof R A Malkin PhD, Prof M M Stevens PhD), Department of Civil and Environmental Engineering (M R Templeton PhD), Department of Infectious Diseases (G S Cooke PhD, N Ford PhD, S D Reid PhD), Department of Infectious Disease Epidemiology (S A J Gregson PhD), Department of Materials (Prof M M Stevens), Department of Medicine (A Blakemore PhD), Department of Primary Care & Public Health (Prof A Majeed MD), Department of Surgery and Cancer (H Ashrafi an MRCS, Prof C Vincent PhD), Faculty of Medicine (Prof R Atun FRCP), Global eHealth Unit (J Car PhD), Imperial College Business School (Prof R Atun FRCP, Prof J Barlow PhD), and Imperial Innovations (HA Penfold PhD), Imperial College London, London, UK Technologies for global health


American Journal of Public Health | 2008

HIV-associated orphanhood and children's psychosocial distress: theoretical framework tested with data from Zimbabwe.

Constance Nyamukapa; Simon Gregson; Ben Lopman; Suzue Saito; Helen Watts; Roeland Monasch; Matthew Jukes

OBJECTIVES We measured the psychosocial effect of orphanhood in a sub-Saharan African population and evaluated a new framework for understanding the causes and consequences of psychosocial distress among orphans and other vulnerable children. METHODS The framework was evaluated using data from 5321 children aged 12 to 17 years who were interviewed in a 2004 national survey in Zimbabwe. We constructed a measure of psychosocial distress using principle components analysis. We used regression analyses to obtain standardized parameter estimates of psychosocial distress and odds ratios of early sexual activity. RESULTS Orphans had more psychosocial distress than did nonorphans. For both genders, paternal, maternal, and double orphans exhibited more-severe distress than did nonorphaned, nonvulnerable children. Orphanhood remained associated with psychosocial distress after we controlled for differences in more-proximate determinants. Maternal and paternal orphans were significantly more likely than were nonorphaned, nonvulnerable children to have engaged in sexual activity. These differences were reduced after we controlled for psychosocial distress. CONCLUSIONS Orphaned adolescents in Zimbabwe suffer greater psychosocial distress than do nonorphaned, nonvulnerable children, which may lead to increased likelihood of early onset of sexual intercourse and HIV infection. The effect of strategies to provide psychosocial support should be evaluated scientifically.


Sexually Transmitted Diseases | 2002

Methods to reduce social desirability bias in sex surveys in low-development settings: experience in Zimbabwe.

Simon Gregson; Tom Zhuwau; Joshua Ndlovu; Constance Nyamukapa

Background Social desirability bias hampers measurement of risk behavior for acquiring STDs and evaluation of control interventions. More confidential data collection methods reduce this bias in Western countries but generally require technology not available in less developed settings. Goal The goal of this report was to describe and evaluate an informal, confidential, low-technology method—Informal Confidential Voting Interviews (ICVIs)—for collecting sexual behavior data in less developed settings. Study Design Reports of multiple sex partners by sexually active, basic-literate, population-based survey participants in rural Zimbabwe randomly assigned to ICVIs and face-to-face interviews (FTFIs) were compared. Results Ninety-two percent of respondents (n = 7823) were sufficiently literate for ICVIs. Error rates were low but higher than in FTFIs. More male and female ICVI respondents interviewed reported multiple current sex partners (OR = 1.33 and 5.24, respectively) and multiple partners in the past month (OR = 1.71 and 2.92) and the past year (OR = 1.35 and 1.97). Conclusion The ICVI method appears to reduce bias but requires further evaluation to assess viability and effect in alternative settings.


Aids Care-psychological and Socio-medical Aspects of Aids\/hiv | 2005

HIV infection and reproductive health in teenage women orphaned and made vulnerable by AIDS in Zimbabwe

Simon Gregson; C Nyamukapa; Geoffrey P. Garnett; Mainford Wambe; James J. Lewis; Peter R. Mason; Stephen K. Chandiwana; Roy M. Anderson

Abstract AIDS has increased the number of orphans and vulnerable children (OVCs) in sub-Saharan Africa who could suffer detrimental life experiences. We investigated whether OVCs have heightened risks of adverse reproductive health outcomes including HIV infection. Data on HIV infection, sexually transmitted infection (STI) symptoms and pregnancy, and common risk factors were collected for OVCs and non-OVCs in a population survey of 1523 teenage children in eastern Zimbabwe between July 2001 and March 2003. Multivariate logistic regression was used to test for statistical association between OVC status, adverse reproductive health outcomes and suspected risk factors. Amongst women aged 15–18 years, OVCs had higher HIV prevalence than non-OVCs (3.2% versus 0.0%; p=0.002) and more common experience of STI symptoms (5.9% versus 3.3%; adjusted odds ratio = 1.75, 95% CI 0.80–3.80) and teenage pregnancy (8.3% versus 1.9%; 4.25, 1.58–11.42). OVCs (overall), maternal orphans and young women with an infected parent were more likely to have received no secondary school education and to have started sex and married, which, in turn, were associated with poor reproductive health. Amongst men aged 17–18 years, OVC status was not associated with HIV infection (0.5% versus 0.0%; p=1.000) or STI symptoms (2.7% versus 1.6%; p=0.529). No association was found between history of medical injections and HIV risk amongst teenage women and men. High proportions of HIV infections, STIs and pregnancies among teenage girls in eastern Zimbabwe can be attributed to maternal orphanhood and parental HIV. Many of these could be averted through further female secondary school education. Predicted substantial expanded increases in orphanhood could hamper efforts to slow the acquisition of HIV infection in successive generations of young adults, perpetuating the vicious cycle of poverty and disease.


Sexually Transmitted Diseases | 2004

Scale-free networks and Sexually transmitted diseases: A description of observed patterns of sexual contacts in Britain and Zimbabwe

Anne Schneeberger; Catherine H Mercer; Simon Gregson; Neil M. Ferguson; Constance Nyamukapa; Roy M. Anderson; Anne M Johnson; Geoff P. Garnett

Background: Sexually transmitted infections spread through a network of contacts created by the formation of sexual partnerships. In physics, networks have been characterized as “scale-free” if they follow a power law with an exponent between 2 and 3. Objective: The objective of this study was to test statistically whether distributions of numbers of sexual partners reported from different populations are well described by power laws. Study Design: Power laws and an exponential null model are fitted by maximum likelihood techniques to reported distributions of numbers of partners. Data are taken from 4 population-based surveys, 3 from Britain and 1 from rural Zimbabwe. Results: The networks can be described by power laws over a number of orders of magnitude. In addition, the derived exponents differ significantly and meaningfully, with an “accelerating network” formed between men who have sex with men (MSM). Conclusions: A scale-free network approach provides a reasonable description of distributions of reported numbers of sexual partners.


The Lancet | 2013

Effects of unconditional and conditional cash transfers on child health and development in Zimbabwe: a cluster-randomised trial

Laura Robertson; Phyllis Mushati; Jeffrey W. Eaton; Lovemore Dumba; Gideon Mavise; Jeremiah C. Makoni; Christina Schumacher; Tom Crea; Roeland Monasch; Lorraine Sherr; Geoffrey P. Garnett; Constance Nyamukapa; Simon Gregson

Summary Background Cash-transfer programmes can improve the wellbeing of vulnerable children, but few studies have rigorously assessed their effectiveness in sub-Saharan Africa. We investigated the effects of unconditional cash transfers (UCTs) and conditional cash transfers (CCTs) on birth registration, vaccination uptake, and school attendance in children in Zimbabwe. Methods We did a matched, cluster-randomised controlled trial in ten sites in Manicaland, Zimbabwe. We divided each study site into three clusters. After a baseline survey between July, and September, 2009, clusters in each site were randomly assigned to UCT, CCT, or control, by drawing of lots from a hat. Eligible households contained children younger than 18 years and satisfied at least one other criteria: head of household was younger than 18 years; household cared for at least one orphan younger than 18 years, a disabled person, or an individual who was chronically ill; or household was in poorest wealth quintile. Between January, 2010, and January, 2011, households in UCT clusters collected payments every 2 months. Households in CCT clusters could receive the same amount but were monitored for compliance with several conditions related to child wellbeing. Eligible households in all clusters, including control clusters, had access to parenting skills classes and received maize seed and fertiliser in December, 2009, and August, 2010. Households and individuals delivering the intervention were not masked, but data analysts were. The primary endpoints were proportion of children younger than 5 years with a birth certificate, proportion younger than 5 years with up-to-date vaccinations, and proportion aged 6–12 years attending school at least 80% of the time. This trial is registered with ClinicalTrials.gov, number NCT00966849. Findings 1199 eligible households were allocated to the control group, 1525 to the UCT group, and 1319 to the CCT group. Compared with control clusters, the proportion of children aged 0–4 years with birth certificates had increased by 1·5% (95% CI −7·1 to 10·1) in the UCT group and by 16·4% (7·8–25·0) in the CCT group by the end of the intervention period. The proportions of children aged 0–4 years with complete vaccination records was 3·1% (−3·8 to 9·9) greater in the UCT group and 1·8% (−5·0 to 8·7) greater in the CCT group than in the control group. The proportions of children aged 6–12 years who attended school at least 80% of the time was 7·2% (0·8–13·7) higher in the UCT group and 7·6% (1·2–14·1) in the CCT group than in the control group. Interpretation Our results support strategies to integrate cash transfers into social welfare programming in sub-Saharan Africa, but further evidence is needed for the comparative effectiveness of UCT and CCT programmes in this region. Funding Wellcome Trust, the World Bank through the Partnership for Child Development, and the Programme of Support for the Zimbabwe National Action Plan for Orphans and Vulnerable Children.


PLOS Medicine | 2011

A Surprising Prevention Success: Why Did the HIV Epidemic Decline in Zimbabwe?

Daniel T. Halperin; Owen Mugurungi; Timothy B. Hallett; Backson Muchini; Bruce Campbell; Tapuwa Magure; Clemens Benedikt; Simon Gregson

Daniel Halperin and colleagues examine reasons for the remarkable decline in HIV in Zimbabwe, in the context of severe social, political, and economic disruption.


AIDS | 2008

From affected to infected? Orphanhood and HIV risk among female adolescents in urban Zimbabwe.

Isolde Birdthistle; Sian Floyd; Auxillia Machingura; Netsai Mudziwapasi; Simon Gregson; Judith R. Glynn

Background:Despite the 15 million children orphaned by AIDS, and fears of sexual vulnerability, little is known about the link between orphanhood and HIV risk. Methods:A random sample of 1283 15 to 19-year-old girls in a high-density suburb of Harare was identified in a cross-sectional survey in 2004. A total of 863 agreed to be interviewed and 839 provided a specimen for HIV and herpes simplex virus type-2 (HSV-2) testing. Sexual health outcomes, sexual behaviours and marriage were assessed by type and timing of orphanhood. Results:Half of the participants were single or double orphans. Prevalence of HIV and/or HSV-2 was higher among orphans than non-orphans [17 versus 12%; age-adjusted odds ratio (aOR) = 1.5; 95% confidence interval (CI) 1.0–2.3]. Associations with orphan status were only significant among the 743 never-married participants. In comparison with non-orphaned peers, increased sexual risk (defined as HSV2-positive, HIV-positive or ever pregnant) was seen among maternal orphans (aOR = 3.6; 95% CI, 1.7–7.8), double orphans (aOR = 2.4; 95% CI, 1.2–4.9), and girls who lost their father before age 12 (aOR = 2.1; 95% CI, 0.9–4.8) but not later (aOR = 0.8; 95% CI, 0.3–2.2). Maternal and double orphans were most likely to initiate sex early and to have had multiple partners. Maternal orphans were least likely to have used a condom at first sex, and to have a regular sexual partner. Experience of forced sex was high in all groups. Conclusions:In urban Zimbabwe, female adolescent orphans are at increased risk of HIV and HSV-2 infection. Infection rates vary by type and age of orphanhood, and marital status, and are associated with high-risk sexual behaviours.


PLOS Medicine | 2007

Impact and Process Evaluation of Integrated Community and Clinic-Based HIV-1 Control: A Cluster-Randomised Trial in Eastern Zimbabwe

Simon Gregson; Saina Adamson; Spiwe Papaya; Jephias Mundondo; Constance Nyamukapa; Peter R. Mason; Geoffrey P. Garnett; Stephen K. Chandiwana; Geoff Foster; Roy M. Anderson

Background HIV-1 control in sub-Saharan Africa requires cost-effective and sustainable programmes that promote behaviour change and reduce cofactor sexually transmitted infections (STIs) at the population and individual levels. Methods and Findings We measured the feasibility of community-based peer education, free condom distribution, income-generating projects, and clinic-based STI treatment and counselling services and evaluated their impact on the incidence of HIV-1 measured over a 3-y period in a cluster-randomised controlled trial in eastern Zimbabwe. Analysis of primary outcomes was on an intention-to-treat basis. The income-generating projects proved impossible to implement in the prevailing economic climate. Despite greater programme activity and knowledge in the intervention communities, the incidence rate ratio of HIV-1 was 1.27 (95% confidence interval [CI] 0.92–1.75) compared to the control communities. No evidence was found for reduced incidence of self-reported STI symptoms or high-risk sexual behaviour in the intervention communities. Males who attended programme meetings had lower HIV-1 incidence (incidence rate ratio 0.48, 95% CI 0.24–0.98), and fewer men who attended programme meetings reported unprotected sex with casual partners (odds ratio 0.45, 95% CI 0.28–0.75). More male STI patients in the intervention communities reported cessation of symptoms (odds ratio 2.49, 95% CI 1.21–5.12). Conclusions Integrated peer education, condom distribution, and syndromic STI management did not reduce population-level HIV-1 incidence in a declining epidemic, despite reducing HIV-1 incidence in the immediate male target group. Our results highlight the need to assess the community-level impact of interventions that are effective amongst targeted population sub-groups.

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Catherine Campbell

London School of Economics and Political Science

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Morten Skovdal

University of Copenhagen

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Phyllis Mushati

London School of Economics and Political Science

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Owen Mugurungi

Ministry of Health and Child Welfare

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Ben Lopman

National Center for Immunization and Respiratory Diseases

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Basia Zaba

Imperial College London

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