Imperial College London

ProfessorTimothyHallett

Faculty of MedicineSchool of Public Health

Professor of Global Health
 
 
 
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Contact

 

+44 (0)20 7594 1150timothy.hallett

 
 
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Location

 

School of Public HealthWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

290 results found

Butler AR, Smith JA, Polis CB, Gregson S, Stanton D, Hallett TBet al., 2013, Modelling the global competing risks of a potential interaction between injectable hormonal contraception and HIV risk, AIDS, Vol: 27, Pages: 105-113, ISSN: 0269-9370

Background: Some, but not all, observational studies have suggested an increase in the risk of HIV acquisition for women using injectable hormonal contraception (IHC).Methods: We used country-level data to explore the effects of reducing IHC use on the number of HIV infections, the number of live births and the resulting net consequences on AIDS deaths and maternal mortality for each country.Results: High IHC use coincides with high HIV incidence primarily in southern and eastern Africa. If IHC increases the risk of HIV acquisition, this could generate 27 000–130 000 infections per year globally, 87–88% of which occur in this region. Reducing IHC use could result in fewer HIV infections but also a substantial increase in live births and maternal mortality in countries with high IHC use, high birth rates and high maternal mortality: mainly southern and eastern Africa, South-East Asia, and Central and South America. For most countries, the net impact of reducing IHC use on maternal and AIDS-related deaths is dependent on the magnitude of the assumed IHC–HIV interaction.Conclusions: If IHC use increases HIV acquisition risk, reducing IHC could reduce new HIV infections; however, this must be balanced against other important consequences, including unintended pregnancy, which impacts maternal and infant mortality. Unless the true effect size approaches a relative risk of 2.19, it is unlikely that reductions in IHC could result in public health benefit, with the possible exception of those countries in southern Africa with the largest HIV epidemics.

Journal article

Butler AR, Hallett TB, 2013, Migration and the transmission of STIs, The New Public Health and STD/HIV Prevention: Personal, Public and Health Systems Approaches, Pages: 65-75, ISBN: 9781461445258

Historically migration has been associated with the spread of ideas, artifacts, knowledge, and, less favorably, disease. This last, dramatically witnessed with the importation in the fifteenth century of small pox to the New World, resulted in dire consequences for the indigenous population [1]. A few hundred years later, small pox was introduced to Australia both in 1780 and 1870, and was a major cause of Aboriginal deaths [2]. With such grave effects it is perhaps no wonder that migration has been intuitively associated with spread of diseases through communities and that migrants are associated or even “blamed” for the spread of disease. More recently, there are reports of South Africans blaming migrants from Zimbabwe for spreading HIV [3, 4]. In any population, the spread of infectious disease depends on the rate of contact between susceptible and infectious individuals [5] and migration provides an important mechanism by which that can continue to happen. However with a sexually transmitted infection (STI) it is not movement and mixing alone but also changes in sexual behavior concomitant with migration that determine the impact on the potential level of disease spread.

Book chapter

Wheelock A, Eisingerich AB, Ananworanich J, Gomez GB, Hallett TB, Dybul MR, Piot Pet al., 2013, Are Thai MSM Willing to Take PrEP for HIV Prevention? An Analysis of Attitudes, Preferences and Acceptance, Plos One, Vol: 8(1)e54288

Journal article

Eaton JW, Hallett TB, Epstein H, 2012, What Might be the Impact of Sexual Partnership "Concurrency'' Behavior Change Communication Campaigns?, SEXUALLY TRANSMITTED DISEASES, Vol: 39, Pages: 899-899, ISSN: 0148-5717

Journal article

Case KK, Ghys PD, Gouws E, Eaton JW, Borquez A, Stover J, Cuchi P, Abu-Raddad LJ, Garnett GP, Hallett TBet al., 2012, Understanding the modes of transmission model of new HIV infection and its use in prevention planning, BULLETIN OF THE WORLD HEALTH ORGANIZATION, Vol: 90, Pages: 831-838, ISSN: 0042-9686

Journal article

Hontelez JAC, Lurie MN, Baernighausen T, Bakker R, Baltussen R, Tanser F, Hallett TB, Newell M-L, de Vlas SJet al., 2012, Treatment as prevention for HIV in South Africa: different models show consistency in occurrence, but difference in timing of elimination and the overall impact of the intervention, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 15, Pages: 113-116

Journal article

Gomez GB, Borquez A, Caceres CF, Segura ER, Grant RM, Garnett GP, Hallett TBet al., 2012, The Potential Impact of Pre-Exposure Prophylaxis for HIV Prevention among Men Who Have Sex with Men and Transwomen in Lima, Peru: A Mathematical Modelling Study, PLOS MEDICINE, Vol: 9, ISSN: 1549-1676

Journal article

Escaleira F, Birger R, Hallett T, Grenfell B, Hodder S, Sinha Aet al., 2012, Cost-effectiveness of test and treat prevention in a high HIV prevalence US city, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 15, Pages: 256-257

Journal article

Smit M, Smit C, Cremin I, Garnett GP, Hallett T, de Wolf Fet al., 2012, Could better tolerated HIV drug regimens improve patient outcome?, AIDS, Vol: 26, Pages: 1953-1959, ISSN: 0269-9370

Journal article

Estill J, Aubriere C, Egger M, Johnson L, Wood R, Garone D, Gsponer T, Wandeler G, Boulle A, Davies M-A, Hallett TB, Keiser Oet al., 2012, Viral load monitoring of antiretroviral therapy, cohort viral load and HIV transmission in Southern Africa: a mathematical modelling analysis, AIDS, Vol: 26, Pages: 1403-1413, ISSN: 0269-9370

Journal article

HIV Modelling Consortium Treatment as Prevention Editorial Writing Group, 2012, HIV treatment as prevention: models, data, and questions--towards evidence-based decision-making., PLOS Medicine, Vol: 9, ISSN: 1549-1277

Antiretroviral therapy (ART) for those infected with HIV can prevent onward transmission of infection, but biological efficacy alone is not enough to guide policy decisions about the role of ART in reducing HIV incidence. Epidemiology, economics, demography, statistics, biology, and mathematical modelling will be central in framing key decisions in the optimal use of ART. PLoS Medicine, with the HIV Modelling Consortium, has commissioned a set of articles that examine different aspects of HIV treatment as prevention with a forward-looking research agenda. Interlocking themes across these articles are discussed in this introduction. We hope that this article, and others in the collection, will provide a foundation upon which greater collaborations between disciplines will be formed, and will afford deeper insights into the key factors involved, to help strengthen the support for evidence-based decision-making in HIV prevention.

Journal article

Delva W, Eaton JW, Meng F, Fraser C, White RG, Vickerman P, Boily M-C, Hallett TBet al., 2012, HIV Treatment as Prevention: Optimising the Impact of Expanded HIV Treatment Programmes, PLOS Medicine, Vol: 9, ISSN: 1549-1277

Until now, decisions about how to allocate ART have largely been based on maximising the therapeutic benefit of ART for patients. Since the results of the HPTN 052 study showed efficacy of antiretroviral therapy (ART) in preventing HIV transmission, there has been increased interest in the benefits of ART not only as treatment, but also in prevention. Resources for expanding ART in the short term may be limited, so the question is how to generate the most prevention benefit from realistic potential increases in the availability of ART. Although not a formal systematic review, here we review different ways in which access to ART could be expanded by prioritising access to particular groups based on clinical or behavioural factors. For each group we consider (i) the clinical and epidemiological benefits, (ii) the potential feasibility, acceptability, and equity, and (iii) the affordability and cost-effectiveness of prioritising ART access for that group. In re-evaluating the allocation of ART in light of the new data about ART preventing transmission, the goal should be to create policies that maximise epidemiological and clinical benefit while still being feasible, affordable, acceptable, and equitable.

Journal article

Boily M-C, Masse B, Alsallaq R, Padian NS, Eaton JW, Vesga JF, Hallett TBet al., 2012, HIV Treatment as Prevention: Considerations in the Design, Conduct, and Analysis of Cluster Randomized Controlled Trials of Combination HIV Prevention, PLOS Medicine, Vol: 9, ISSN: 1549-1277

Journal article

Johnson LF, Hallett TB, Rehle TM, Dorrington REet al., 2012, The effect of changes in condom usage and antiretroviral treatment coverage on human immunodeficiency virus incidence in South Africa: a model-based analysis, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 9, Pages: 1544-1554, ISSN: 1742-5689

Journal article

Eaton JW, Johnson LF, Salomon JA, Baernighausen T, Bendavid E, Bershteyn A, Bloom DE, Cambiano V, Fraser C, Hontelez JAC, Humair S, Klein DJ, Long EF, Phillips AN, Pretorius C, Stover J, Wenger EA, Williams BG, Hallett TBet al., 2012, HIV Treatment as Prevention: Systematic Comparison of Mathematical Models of the Potential Impact of Antiretroviral Therapy on HIV Incidence in South Africa, PLOS MEDICINE, Vol: 9, ISSN: 1549-1277

Journal article

Delva W, Wilson DP, Abu-Raddad L, Gorgens M, Wilson D, Hallett TB, Welte Aet al., 2012, HIV Treatment as Prevention: Principles of Good HIV Epidemiology Modelling for Public Health Decision-Making in All Modes of Prevention and Evaluation, PLOS MEDICINE, Vol: 9, ISSN: 1549-1277

Journal article

Hewett PC, Hallett TB, Mensch BS, Dzekedzeke K, Zimba-Tembo S, Garnett GP, Todd PEet al., 2012, Sex with stitches: assessing the resumption of sexual activity during the postcircumcision wound-healing period, AIDS, Vol: 26, Pages: 749-756, ISSN: 0269-9370

Journal article

Chemaitelly H, Cremin I, Shelton J, Hallett TB, Abu-Raddad LJet al., 2012, Distinct HIV discordancy patterns by epidemic size in stable sexual partnerships in sub-Saharan Africa, SEXUALLY TRANSMITTED INFECTIONS, Vol: 88, Pages: 51-57, ISSN: 1368-4973

Journal article

Hallett TB, Gregson S, Dube S, Mapfeka ES, Mugurungi O, Garnett GPet al., 2011, Estimating the resources required in the roll-out of universal access to antiretroviral treatment in Zimbabwe, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: 621-628, ISSN: 1368-4973

Journal article

Hallett TB, Baeten JM, Heffron R, Barnabas R, de Bruyn G, Cremin I, Delany S, Garnett GP, Gray G, Johnson L, McIntyre J, Rees H, Celum Cet al., 2011, Optimal Uses of Antiretrovirals for Prevention in HIV-1 Serodiscordant Heterosexual Couples in South Africa: A Modelling Study, PLOS MEDICINE, Vol: 8, ISSN: 1549-1676

Journal article

Garnett GP, Cousens S, Hallett TB, Steketee R, Walker Net al., 2011, Mathematical models in the evaluation of health programmes, LANCET, Vol: 378, Pages: 515-525, ISSN: 0140-6736

Journal article

White P, Birger R, Saunders J, Estcourt C, Hallett T, Caffrey O, Mercer C, Roberts Tet al., 2011, IS URETHRAL SMEAR MICROSCOPY IN ASYMPTOMATIC MEN EFFECTIVE IN REDUCING MAJOR <i>M GENITALIUM</i> INFECTION SEQUELAE IN WOMEN?, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A293-A293, ISSN: 1368-4973

Journal article

Hewett P, Mensch B, Hallett T, Garnett G, Dzekedzeke K, Todd Pet al., 2011, SEX WITH STITCHES, THE RESUMPTION OF SEXUAL ACTIVITY DURING THE POST-CIRCUMCISION HEALING PERIOD IN ZAMBIA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A56-A57, ISSN: 1368-4973

Journal article

Eaton J, Takavarasha F, Gregson S, Hallett T, Mason P, Robertson L, Schumacher C, Nyamukapa C, Garnett Get al., 2011, INCREASING ADOLESCENT HIV PREVALENCE IN NORTHEASTERN ZIMBABWE: EVIDENCE OF LONG-TERM SURVIVORS OF MOTHER TO CHILD TRANSMISSION, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A28-A29, ISSN: 1368-4973

Journal article

Gerver SM, Xu F, Tian L, Griffin J, Garnett GP, Markowitz LE, Hallett TBet al., 2011, Incidence Rate of Herpes Simplex Virus type 2 (HSV-2) in the US, 1988-2008, International Society for Sexually Transmitted Disease Research

Background: HSV-2 infection remains a major public health problem in the US, where the prevalence is 16.2% in persons aged 14-49. In this report, we provide national estimates of new HSV-2 infections in the US and examine trends in incidence over the past two decades.Methods: A simple catalytic model was used to estimate HSV-2 force of infection (FOI), defined as the incidence of HSV-2 in the susceptible population, from National Health and Nutrition Examination Surveys (NHANES) in the US from 1988 through 2008. HSV-2 serology was included in the nationally representative surveys during 1988-1994 (NHANES III) and in continuous NHANES from 1999-2008. Incidence rates and trends over time were estimated by age, sex and race/ethnic group for non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans.Results: HSV-2 FOI rates were highest in non-Hispanic blacks and lowest in non-Hispanic whites, with the FOI among 25 year old non-Hispanic black women more than 13 times greater than white men of the same age. Rates were highest between ages 25-35 years for all sex-race/ethnicity groups (peak in non-Hispanic white and black women aged 25 years, in non-Hispanic white and black men aged 35 years and in Mexican-American women in their early-thirties) except for Mexican-American men, for whom there was less variation in FOI by age. Over the last twenty years, age-adjusted FOI rates were stable for the sex-race/ethnicity groups examined except for non-Hispanic white and Mexican-American women, in which there were decreases after 2002 and 2001, respectively. FOI rates were lower in men than women among non-Hispanic blacks and Mexican-Americans, and in non-Hispanic whites prior to 2002. Overall, the estimated number of new HSV-2 infections in 2007-2008, among these three groups, aged 14-49 years, was in excess of 750,000, with 48% (~360,000) occurring in women and 52% (~392,000) in men. Nearly half (45%) of all infections occurred in persons under 25 years old (34% and 57

Conference paper

Smit M, Smit C, Cremin I, Hallett T, De Wolf F, Garnett GPet al., 2011, New Drugs Trageting Toxicities Have HIghest Hope of Impacting Patients Prognosis, International Society for Sexually Transmitted Diseases Research

Conference paper

Elmes J, Nhongo K, Hallett T, White P, Mutsindiri R, Garnett G, Nyamukapa C, Gregson Set al., 2011, WHO ARE THE WOMEN AT RISK OF HIV INFECTION IN RURAL ZIMBABWE AND HOW MANY ARE THERE? INSIGHTS INTO THEIR CHARACTERISTICS, LOCATIONS, AND BEHAVIOURS, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A41-A41, ISSN: 1368-4973

Journal article

Alsallaq R, Baeten J, Hughes J, Abu-Raddad L, Celum C, Hallett Tet al., 2011, MODELLING THE EFFECTIVENESS OF COMBINATION PREVENTION FROM A HOUSE-TO-HOUSE HIV TESTING PLATFORM IN KWAZULU NATAL, SOUTH AFRICA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A36-A36, ISSN: 1368-4973

Journal article

Cremin I, Hallett T, Dybul M, Piot P, Garnett Get al., 2011, PRE-EXPOSURE PROPHYLAXIS FOR HIV PREVENTION, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A36-A36, ISSN: 1368-4973

Journal article

Borquez A, Gomez GB, Caceres CF, Segura ER, Grant RM, Garnett GP, Hallett TBet al., 2011, THE POTENTIAL IMPACT OF PRE-EXPOSURE PROPHYLAXIS FOR HIV PREVENTION AMONG MEN WHO HAVE SEX WITH MEN (MSM) IN LIMA, PERU, SEXUALLY TRANSMITTED INFECTIONS, Vol: 87, Pages: A350-A350, ISSN: 1368-4973

Journal article

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