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

 

Norfolk PlaceSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
to

199 results found

Selinger C, Bershteyn A, Dimitrov DT, Adamson BJS, Revill P, Hallett TB, Phillips AN, Bekker L-G, Rees H, Gray Get al., 2019, Targeting and vaccine durability are key for population-level impact and cost-effectiveness of a pox-protein HIV vaccine regimen in South Africa., Vaccine, Vol: 37, Pages: 2258-2267

BACKGROUND: RV144 is to date the only HIV vaccine trial to demonstrate efficacy, albeit rapidly waning over time. The HVTN 702 trial is currently evaluating in South Africa a similar vaccine formulation to that of RV144 for subtype C HIV with additional boosters (pox-protein regimen). Using a detailed stochastic individual-based network model of disease transmission calibrated to the HIV epidemic, we investigate population-level impact and maximum cost of an HIV vaccine to remain cost-effective. METHODS: Consistent with the original pox-protein regimen, we model a primary series of five vaccinations meeting the goal of 50% cumulative efficacy 24 months after the first dose and include two-yearly boosters that maintain durable efficacy over 10 years. We simulate vaccination programs in South Africa starting in 2027 under various vaccine targeting and HIV treatment and prevention assumptions. RESULTS: Our analysis shows that this partially effective vaccine could prevent, at catch-up vaccination with 60% coverage, up to 941,000 (15.6%) new infections between 2027 and 2047 assuming current trends of antiretroviral treatment. An impact of up to 697,000 (11.5%) infections prevented could be achieved by targeting age cohorts of highest incidence. Economic evaluation indicates that, if treatment scale-up was achieved, vaccination could be cost-effective at a total cost of less than $385 and $62 per 10-year series (cost-effectiveness thresholds of $5,691 and $750). CONCLUSIONS: While a partially effective, rapidly waning vaccine could help to prevent HIV infections, it will not eliminate HIV as a public health priority in sub-Saharan Africa. Vaccination is expected to be most effective under targeted delivery to age groups of highest HIV incidence. Awaiting results of trial, the introduction of vaccination should go in parallel with continued innovation in HIV prevention, including studies to determine the costs of delivery and feasibility and further research into products

JOURNAL ARTICLE

Heffernan A, Cooke GS, Nayagam S, Thursz M, Hallett TBet al., 2019, Scaling up prevention and treatment towards the elimination of hepatitis C: a global mathematical model, LANCET, Vol: 393, Pages: 1319-1329, ISSN: 0140-6736

JOURNAL ARTICLE

Borquez A, Guanira JV, Revill P, Caballero P, Silva-Santisteban A, Kelly S, Salazar X, Bracamonte P, Minaya P, Hallett TB, Caceres CFet al., 2019, The impact and cost-effectiveness of combined HIV prevention scenarios among transgender women sex-workers in Lima, Peru: a mathematical modelling study, LANCET PUBLIC HEALTH, Vol: 4, Pages: E127-E136, ISSN: 2468-2667

JOURNAL ARTICLE

Mangal TD, Meireles MV, Pati Pascom AR, Coelho RDA, Benzaken AS, Hallett TBet al., 2019, Determinants of survival of people living with HIV/AIDS on antiretroviral therapy in Brazil 2006-2015, BMC INFECTIOUS DISEASES, Vol: 19, ISSN: 1471-2334

JOURNAL ARTICLE

Stopard IJ, Mcgillen JB, Hauck K, Hallett TBet al., 2019, The influence of constraints on the efficient allocation of resources for HIV prevention: a modelling study., AIDS

OBJECTIVE: To investigate how 'real-world' constraints on the allocative and technical efficiency of HIV prevention programmes affect resource allocation and the number of infections averted. DESIGN: Epidemiological modelling and economic analyses in Benin, South Africa and Tanzania. METHODS: We simulated different HIV prevention programmes, and first determined the most efficient allocation of resources, in which the HIV prevention budget is shared between specific interventions, risk-groups and provinces to maximise the number of infections averted. We then identified the efficient allocation of resources and achievable impact given constraints to allocative efficiency: earmarking (provinces with budgets fund PrEP for low-risk women first), meeting treatment targets (provinces with budgets fund UTT first) and minimizing changes in the geographical distribution of funds. We modelled technical inefficiencies as a reduction in the coverage of PrEP or UTT, which were factored into the resource allocation process or took effect following the allocation. Each scenario was investigated over a range of budgets, such that the impact reaches its maximum. RESULTS: The 'earmarking', 'meeting targets' and 'minimizing change' constraints reduce the potential impact of HIV prevention programmes, but at the higher budgets these constraints have little to no effect (approximately 35 billion US$ in Tanzania). Over-estimating technical efficiencies results in a loss of impact compared to what would be possible if technical efficiencies were known accurately. CONCLUSIONS: Failing to account for constraints on allocative and technical efficiency can result in the overestimation of the health gains possible, and for technical inefficiencies the allocation of an inefficient strategy.This is an open access article distributed under the Creative Commons Attribution License 4.0, (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work

JOURNAL ARTICLE

Mangal TD, Pascom ARP, Vesga JF, Meireles MV, Benzaken AS, Hallett TBet al., 2019, Estimating HIV incidence from surveillance data indicates a second wave of infections in Brazil., Epidemics

Emerging evidence suggests that HIV incidence rates in Brazil, particularly among men, may be rising. Here we use Brazil's integrated health systems data to develop a mathematical model, reproducing the complex surveillance systems and providing estimates of HIV incidence, number of people living with HIV (PLHIV), reporting rates and ART initiation rates. An age-structured deterministic model with a flexible spline was used to describe the natural history of HIV along with reporting and treatment rates. Individual-level surveillance data for 1,077,295 cases (HIV/AIDS diagnoses, ART dispensations, CD4 counts and HIV/AIDS-related deaths) were used to calibrate the model using Bayesian inference. The results showed a second wave of infections occurring after 2001 and 56,000 (95% Credible Interval 43,000-71,000) new infections in 2015, 37,000 (95% CrI 28,000-54,000) infections in men and 16,000 (95% CrI 10,000-23,000) in women. The estimated number of PLHIV by end-2015 was 838,000 (95% CrI 675,000-1,083,000), with 80% (95% CrI 62-98%) of those individuals reported to the Ministry of Health. Women were more likely to be diagnosed and reported than men; 86.8% of infected women had been reported compared with 75.7% of men. Likewise, ART initiation rates for women were higher than those for men. The second wave contradicts previous estimates of HIV incidence trends in Brazil and there were persistent differences in the rates of accessing care between men and women. Nevertheless, the Brazilian HIV program has achieved high rates of detection and treatment, making considerable progress over the past ten years.

JOURNAL ARTICLE

Schaefer R, Gregson S, Fearon E, Hensen B, Hallett TB, Hargreaves JRet al., 2019, HIV prevention cascades: a unifying framework to replicate the successes of treatment cascades, LANCET HIV, Vol: 6, Pages: E60-E66, ISSN: 2352-3018

JOURNAL ARTICLE

Olney JJ, Eaton JW, Braitstein P, Hogan JW, Hallett TBet al., 2019, Response to Questionable assumptions mar modelling of Kenya home-based testing campaigns - a comment on "Optimal timing of HIV home-based counselling and testing rounds in Western Kenya" (Olney etal. 2018), JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 22, ISSN: 1758-2652

JOURNAL ARTICLE

Anderson S-J, Garnett GP, Enstone J, Hallett TBet al., 2018, The importance of local epidemic conditions in monitoring progress towards HIV epidemic control in Kenya: a modelling study, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 21, ISSN: 1758-2652

JOURNAL ARTICLE

Woods B, Rothery C, Anderson S-J, Eaton JW, Revill P, Hallett TB, Claxton Ket al., 2018, Appraising the value of evidence generation activities: an HIV modelling study, BMJ GLOBAL HEALTH, Vol: 3, ISSN: 2059-7908

JOURNAL ARTICLE

Ghys PD, Williams BG, Over M, Hallett TB, Godfrey-Faussett Pet al., 2018, Epidemiological metrics and benchmarks for a transition in the HIV epidemic, PLOS MEDICINE, Vol: 15, ISSN: 1549-1676

JOURNAL ARTICLE

Fu H, Lin H-H, Hallett TB, Arinaminpathy Net al., 2018, Modelling the effect of discontinuing universal Bacillus Calmette-Guerin vaccination in an intermediate tuberculosis burden setting, VACCINE, Vol: 36, Pages: 5902-5909, ISSN: 0264-410X

JOURNAL ARTICLE

McGillen JB, Stover J, Klein DJ, Xaba S, Ncube G, Mhangara M, Chipendo GN, Taramusi I, Beacroft L, Hallett TB, Odawo P, Manzou R, Korenromp ELet al., 2018, The emerging health impact of voluntary medical male circumcision in Zimbabwe: An evaluation using three epidemiological models, PLOS ONE, Vol: 13, ISSN: 1932-6203

JOURNAL ARTICLE

Phillips A, Cambiano V, Bansi-Matharu L, Nakagawa F, Wilson D, Jani I, Apollo T, Sculpher M, Hallett T, Kerr C, van Oosterhout J, Eaton J, Estill J, Williams B, Doi N, Cowan F, Keiser O, Ford D, Hatzold K, Barnabas R, Ayles H, Meyer-Rath G, Nelson L, Johnson C, Baggaley R, Fakoya A, Jahn A, Revill Pet al., 2018, Cost-of-testing-per-new-HIV-diagnosis as a metric for monitoring cost-effectiveness of testing programmes in low income settings in Southern Africa: health economic modelling analysis, Publisher: JOHN WILEY & SONS LTD, Pages: 27-28, ISSN: 1758-2652

CONFERENCE PAPER

Olney JJ, Eaton JW, Braitstein P, Hogan JW, Hallett TBet al., 2018, Optimal timing of HIV home-based counselling and testing rounds in Western Kenya, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 21, ISSN: 1758-2652

JOURNAL ARTICLE

Heffernan A, Hallett T, Thursz M, Cooke G, Nayagam Set al., 2018, Global scale-up of hepatitis C interventions will reduce burden but not eliminate the disease, 16th International Symposium on Viral Hepatitis and Liver Diseases (ISVHLD), Publisher: WILEY, Pages: 26-26, ISSN: 1352-0504

CONFERENCE PAPER

Meyer-Rath G, McGillen JB, Cuadros DF, Hallett TB, Bhatt S, Wabiri N, Tanser F, Rehle Tet al., 2018, Targeting the right interventions to the right people and places: the role of geospatial analysis in HIV program planning, AIDS, Vol: 32, Pages: 957-963, ISSN: 0269-9370

JOURNAL ARTICLE

Hecht R, Hiebert L, Spearman WC, Sonderup M, Guthrie T, Hallett TB, Nayagam S, Razavi H, Soe-Lin S, Vilakazi-Nhlapo K, Pillay Y, Resch Set al., 2018, The investment case for hepatitis B and C in South Africa: adaptation and innovation in policy analysis for disease program scale-up, HEALTH POLICY AND PLANNING, Vol: 33, Pages: 528-538, ISSN: 0268-1080

JOURNAL ARTICLE

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

JOURNAL ARTICLE

Anderson S-J, Ghys PD, Ombam R, Hallett TBet al., 2018, Frontloading HIV financing maximizes the achievable impact of HIV prevention, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 21, ISSN: 1758-2652

JOURNAL ARTICLE

Phillips AN, Cambiano V, Nakagawa F, Revill P, Jordan MR, Hallett TB, Doherty M, De Luca A, Lundgren JD, Mhangara M, Apollo T, Mellors J, Nichols B, Parikh U, Pillay D, de Wit TR, Sigaloff K, Havlir D, Kuritzkes DR, Pozniak A, van de Vijver D, Vitoria M, Wainberg MA, Raizes E, Bertagnolio Set al., 2018, Cost-effectiveness of public-health policy options in the presence of pretreatment NNRTI drug resistance in sub-Saharan Africa: a modelling study, LANCET HIV, Vol: 5, Pages: E146-E154, ISSN: 2352-3018

JOURNAL ARTICLE

Smit M, van Zoest RA, Nichols BE, Vaartjes I, Smit C, van der Valk M, van Sighem A, Wit FW, Hallett TB, Reiss Pet al., 2018, Cardiovascular Disease Prevention Policy in Human Immunodeficiency Virus: Recommendations From a Modeling Study, CLINICAL INFECTIOUS DISEASES, Vol: 66, Pages: 743-750, ISSN: 1058-4838

JOURNAL ARTICLE

McRobie E, Matovu F, Nanyiti A, Nonvignon J, Abankwah DNY, Case KK, Hallett TB, Hanefeld J, Conteh Let al., 2018, National responses to global health targets: exploring policy transfer in the context of the UNAIDS '90-90-90' treatment targets in Ghana and Uganda, HEALTH POLICY AND PLANNING, Vol: 33, Pages: 17-33, ISSN: 0268-1080

JOURNAL ARTICLE

Smith MK, Jewell BL, Hallett TB, Cohen MSet al., 2018, Treatment of HIV for the Prevention of Transmission in Discordant Couples and at the Population Level, HIV VACCINES AND CURE: THE PATH TOWARDS FINDING AN EFFECTIVE CURE AND VACCINE, Vol: 1075, Pages: 125-162, ISSN: 0065-2598

JOURNAL ARTICLE

Anderson S-J, Ghys PD, Ombam R, Hallett TBet al., 2017, HIV prevention where it is needed most: comparison of strategies for the geographical allocation of interventions, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 20, ISSN: 1758-2652

JOURNAL ARTICLE

McGillen JB, Sharp A, Honermann B, Millett G, Collins C, Hallett TBet al., 2017, Consequences of a changing US strategy in the global HIV investment landscape, AIDS, Vol: 31, Pages: F19-F23, ISSN: 0269-9370

JOURNAL ARTICLE

Nayagam S, Sicuri E, Lemoine M, Easterbrook P, Conteh L, Hallett TB, Thursz Met al., 2017, Economic evaluations of HBV testing and treatment strategies and applicability to low and middle-income countries, BMC INFECTIOUS DISEASES, Vol: 17, Pages: 107-116, ISSN: 1471-2334

JOURNAL ARTICLE

Smit M, Cassidy R, Cozzi-Lepri A, Quiros-Roldan E, Girardi E, Mammone A, Antinori A, Saracino A, Bai F, Rusconi S, Magnani G, Castelli F, Hsue P, Monforte AD, Hallett TBet al., 2017, Projections of non-communicable disease and health care costs among HIV-positive persons in Italy and the USA: A modelling study, PLOS ONE, Vol: 12, ISSN: 1932-6203

JOURNAL ARTICLE

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

JOURNAL ARTICLE

McGillen J, Sharp A, Honermann B, Millett G, Collins C, Hallett Tet al., 2017, How changes in United States funding policies could impact the HIV epidemic in sub-Saharan Africa, Publisher: INT AIDS SOCIETY, Pages: 64-65, ISSN: 1758-2652

CONFERENCE PAPER

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