Imperial College London

Dr Kate Mitchell

Faculty of MedicineSchool of Public Health

Advanced Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 3342kate.mitchell Website

 
 
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Location

 

UG4Norfolk PlaceSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
to

53 results found

Silhol R, Geidelberg L, Mitchell K, Mishra S, Dimitrov D, Bowring A, Behanzin L, Guedou F, Diabate S, Schwartz S, Billong S, Mfochive Njindam I, Levitt D, Mukandavire C, Maheu-Giroux M, Rönn M, Dalal S, Vickerman P, Baral S, Alary M, Boily M-Cet al., 2021, Assessing the potential impact of disruptions due to COVID-19 on HIV among key and lower-risk populations in the largest cities of Cameroon and Benin, JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 87, Pages: 899-911, ISSN: 1525-4135

Background: The COVID-19 pandemic indirectly impacts HIV epidemiology in Central/West Africa. We estimated the potential impact of COVID-19-related disruptions to HIV prevention/treatment services and sexual partnerships on HIV incidence and HIV-related deaths among key populations including female sex workers (FSW), their clients, men who have sex with men (MSM), and overall.Setting: Yaoundé (Cameroon) and Cotonou (Benin).Methods: We used mathematical models of HIV calibrated to city- and risk-population-specific demographic/behavioural/epidemic data. We estimated the relative change in 1-year HIV incidence and HIV-related deaths for various disruption scenarios of HIV prevention/treatment services and decreased casual/commercial partnerships, compared to a scenario without COVID-19.Results: A 50% reduction in condom use in all partnerships over 6 months would increase 1-year HIV incidence by 39%, 42%, 31% and 23% among MSM, FSW, clients, and overall in Yaoundé respectively, and 69%, 49% and 23% among FSW, clients and overall respectively in Cotonou. Combining a 6-month interruption of ART initiation and 50% reduction in HIV prevention/treatment use would increase HIV incidence by 50% and HIV-related deaths by 20%. This increase in HIV infections would be halved by a simultaneous 50% reduction in casual and commercial partnerships.Conclusions: Reductions in condom use following COVID-19 would increase infections among key populations disproportionately, particularly FSW in Cotonou, who need uninterrupted condom provision. Disruptions in HIV prevention/treatment services have the biggest impacts on HIV infections and deaths overall, only partially mitigated by equal reductions in casual/commercial sexual partnerships. Maintaining ART provision must be prioritised to minimise short-term excess HIV-related deaths.

Journal article

Booton RD, Ong JJ, Lee A, Liu A, Huang W, Wei C, Tang W, Ma W, Vickerman P, Tucker JD, Mitchell KMet al., 2021, Modelling the impact of an HIV testing intervention on HIV transmission among men who have sex with men in China, HIV Medicine, Vol: 22, Pages: 467-477, ISSN: 1464-2662

ObjectivesAn intervention developed through participatory crowdsourcing methods increased HIV self‐testing among men who have sex with men [MSM; relative risk (RR) = 1.89]. We estimated the long‐term impact of this intervention on HIV transmission among MSM in four cities (Guangzhou, Shenzhen, Jinan and Qingdao).MethodsA mathematical model of HIV transmission, testing and treatment among MSM in China was parameterized using city‐level demographic and sexual behaviour data and calibrated to HIV prevalence, diagnosis and antiretroviral therapy (ART) coverage data. The model was used to project the HIV infections averted over 20 years (2016–2036) from the intervention to increase self‐testing, compared with current testing rates.ResultsRunning the intervention once would avert < 2.2% infections over 20 years. Repeating the intervention (RR = 1.89) annually would avert 6.4–10.7% of new infections, while further increases in the self‐testing rate (hypothetical RR = 3) would avert 11.7–20.7% of new infections.ConclusionsRepeated annual interventions would give a three‐ to seven‐fold increase in long‐term impact compared with a one‐off intervention. Other interventions will be needed to more effectively reduce the HIV burden in this population.

Journal article

Soni N, Giguère K, Boily M-C, Fogel JM, Maheu-Giroux M, Dimitrov D, Eshleman SH, Mitchell Ket al., 2021, Under-reporting of known HIV-positive status among people living with HIV: a systematic review and meta-analysis, AIDS and Behavior, ISSN: 1090-7165

Monitoring progress towards the UNAIDS ‘first 90’ target requires accurate estimates of levels of diagnosis among people living with HIV (PLHIV), which is often estimated using self-report. We conducted a systematic review and meta-analysis quantifying under-reporting of known HIV-positive status using objective knowledge proxies. Databases were searched for studies providing self-reported and biological/clinical markers of prior knowledge of HIV-positive status among PLHIV. Random-effects models were used to derive pooled estimates of levels of under-reporting. Thirty-two estimates from 26 studies were included (41,465 PLHIV). The pooled proportion under-reporting known HIV-positive status was 20% (95% confidence interval 13–26%, I2 = 99%). In sub-group analysis, under-reporting was higher among men who have sex with men (32%, number of estimates [Ne] = 10) compared to the general population (9%, Ne = 10) and among Black (18%, Ne = 5) than non-Black (3%, Ne = 3) individuals. Supplementing self-reported data with biological/clinical proxies may improve the validity of the ‘first 90’ estimates.

Journal article

Mitchell KM, Dimitrov D, Silhol R, Geidelberg L, Moore M, Liu A, Beyrer C, Mayer KH, Baral S, Boily M-Cet al., 2021, The potential effect of COVID-19-related disruptions on HIV incidence and HIV-related mortality among men who have sex with men in the USA: a modelling study, The Lancet HIV, Vol: 8, Pages: e206-e215, ISSN: 2405-4704

BACKGROUND: During the COVID-19 pandemic, men who have sex with men (MSM) in the USA have reported similar or fewer sexual partners and reduced HIV testing and care access compared with before the pandemic. Pre-exposure prophylaxis (PrEP) use has also declined. We aimed to quantify the potential effect of COVID-19 on HIV incidence and HIV-related mortality among US MSM. METHODS: We used a calibrated, deterministic, compartmental HIV transmission model for MSM in Baltimore (MD, USA) and available data on COVID-19-related disruptions to HIV services to predict effects of reductions in sexual partners (0%, 25%, 50%), condom use (5%), HIV testing (20%), viral suppression (10%), PrEP initiations (72%), PrEP adherence (9%), and antiretroviral therapy (ART) initiations (50%). In our main analysis, we modelled disruptions due to COVID-19 starting Jan 1, 2020, and lasting 6 months. We estimated the median change in cumulative new HIV infections and HIV-related deaths among MSM over 1 and 5 years, compared with a base case scenario without COVID-19-related disruptions. FINDINGS: A 25% reduction in sexual partners for 6 months among MSM in Baltimore, without HIV service changes, could reduce new HIV infections by median 12·2% (95% credible interval 11·7 to 12·8) over 1 year and median 3·0% (2·6 to 3·4) over 5 years. In the absence of changes in sexual behaviour, the 6-month estimated reductions in condom use, HIV testing, viral suppression, PrEP initiations, PrEP adherence, and ART initiations combined are predicted to increase new HIV infections by median 10·5% (5·8 to 16·5) over 1 year, and by median 3·5% (2·1 to 5·4) over 5 years. Disruptions to ART initiations and viral suppression are estimated to substantially increase HIV-related deaths (ART initiations by median 1·7% [0·8 to 3·2], viral suppression by median 9·5% [5·2 to 15·9]) over 1 year, with

Journal article

Booton RD, Fu G, MacGregor L, Li J, Ong JJ, Tucker JD, Turner KM, Tang W, Vickerman P, Mitchell KMet al., 2021, The impact of disruptions due to COVID-19 on HIV transmission and control among men who have sex with men in China, Journal of the International AIDS Society, Vol: 24, ISSN: 1758-2652

INTRODUCTION: The COVID-19 pandemic is impacting HIV care globally, with gaps in HIV treatment expected to increase HIV transmission and HIV-related mortality. We estimated how COVID-19-related disruptions could impact HIV transmission and mortality among men who have sex with men (MSM) in four cities in China, over a one- and five-year time horizon. METHODS: Regional data from China indicated that the number of MSM undergoing facility-based HIV testing reduced by 59% during the COVID-19 pandemic, alongside reductions in ART initiation (34%), numbers of all sexual partners (62%) and consistency of condom use (25%), but initial data indicated no change in viral suppression. A mathematical model of HIV transmission/treatment among MSM was used to estimate the impact of disruptions on HIV infections/HIV-related deaths. Disruption scenarios were assessed for their individual and combined impact over one and five years for 3/4/6-month disruption periods, starting from 1 January 2020. RESULTS: Our model predicted new HIV infections and HIV-related deaths would be increased most by disruptions to viral suppression, with 25% reductions (25% virally suppressed MSM stop taking ART) for a three-month period increasing HIV infections by 5% to 14% over one year and deaths by 7% to 12%. Observed reductions in condom use increased HIV infections by 5% to 14% but had minimal impact (<1%) on deaths. Smaller impacts on infections and deaths (<3%) were seen for disruptions to facility HIV testing and ART initiation, but reduced partner numbers resulted in 11% to 23% fewer infections and 0.4% to 1.0% fewer deaths. Longer disruption periods (4/6 months) amplified the impact of disruption scenarios. When realistic disruptions were modelled simultaneously, an overall decrease in new HIV infections occurred over one year (3% to 17%), but not for five years (1% increase to 4% decrease), whereas deaths mostly increased over one year (1% to 2%) and five years (1.2 increase to 0.3 d

Journal article

Geidelberg L, Mitchell KM, Alary M, Mboup A, Béhanzin L, Guédou F, Geraldo N, Goma-Matsétsé E, Giguère K, Aza-Gnandji M, Kessou L, Diallo M, Kêkê RK, Bachabi M, Dramane K, Lafrance C, Affolabi D, Diabaté S, Gagnon M-P, Zannou DM, Gangbo F, Silhol R, Cianci F, Vickerman P, Boily M-Cet al., 2021, A mathematical model impact analysis of a real-life pre-exposure prophylaxis and treatment-as-prevention study among female sex workers in Cotonou, Benin, JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 86, Pages: e28-e42, ISSN: 1525-4135

BACKGROUND: Daily pre-exposure prophylaxis (PrEP) and treatment-as-prevention (TasP) reduce HIV acquisition and transmission risk, respectively. A demonstration study (2015-2017) assessed TasP and PrEP feasibility among female sex workers (FSW) in Cotonou, Benin. SETTING: Cotonou, Benin METHODS:: We developed a compartmental HIV transmission model, featuring PrEP, and ART among the high-risk (FSW, clients) and low-risk populations, calibrated to historical epidemiological and demonstration study data, reflecting observed lower PrEP uptake, adherence and retention compared to TasP. We estimated the population-level impact of the two-year study and several twenty-year intervention scenarios, varying coverage and adherence independently and together. We report the percentage (median, 2.5th-97.5th percentile uncertainty interval (95%UI)) of HIV infections prevented comparing the intervention and counterfactual (2017 coverages: 0% PrEP, 49% ART) scenarios. RESULTS: The two-year study (2017 coverages: 9% PrEP, 83% ART) prevented an estimated 8% (95%UI 6-12) and 6% (3-10) infections among FSW over two and twenty years, respectively, compared to 7% (3-11) and 5% (2-9) overall. The PrEP and TasP arms prevented 0.4% (0.2-0.8) and 4.6% (2.2-8.7) infections overall over 20 years, respectively. Twenty-year PrEP and TasP scale-ups (2035 coverages: 47% PrEP, 88% ART) prevented 21% (17-26) and 17% (10-27) infections among FSW respectively, and 5% (3-10) and 17% (10-27) overall. Compared to TasP scale-up alone, PrEP and TasP combined scale-up prevented 1.9x and 1.2x more infections among FSW and overall, respectively. CONCLUSIONS: The modest demonstration study impact was modest, and mostly from TasP. Increasing PrEP adherence and coverage improves impact substantially among FSW, but little overall. We recommend TasP in prevention packages.

Journal article

Wong NS, Powers KA, Tucker JD, Lee SS, Goh BT, Zhao P, Chen L, Wang C, Yang LG, Yang B, Zheng H, Huang S, Mitchell KMet al., 2021, Modelling the impact of a sex work crackdown on syphilis transmission among female sex workers and their clients in South China, SEXUALLY TRANSMITTED INFECTIONS, Vol: 97, Pages: 45-50, ISSN: 1368-4973

Journal article

Moore JR, Donnell DJ, Boily M-C, Mitchell KM, Delany-Moretlwe S, Bekker L-G, Mgodi NM, El-Sadr W, Cohen MS, Celum CL, Dimitrov Det al., 2020, Model-based predictions of HIV incidence among African women using HIV risk behaviors and community-level data on male HIV prevalence and viral suppression., JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 85, Pages: 423-429, ISSN: 1525-4135

BACKGROUND: Pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate and emtricitabine has proven highly effective in preventing HIV acquisition and is therefore offered to all participants in the control group as part of the standard of care package in many new HIV prevention studies. We propose a methodology for predicting HIV incidence in a hypothetical "placebo arm" for open-label studies or clinical trials with active control among African women. We apply the method to an open-label PrEP study, HIV Prevention Trials Network 082, which tested strategies to improve PrEP adherence in young African women all of whom were offered PrEP. METHODS: Our model predicted HIV infection risk for female study cohorts in sub-Saharan Africa using baseline behavioral risk factors and contemporary HIV prevalence and viral suppression in the local male population. The model was calibrated to HIV incidence in the Vaginal and Oral Interventions to Control the Epidemic study. RESULTS: Our model reproduced the annual HIV incidence of 3.2%-4.8% observed over 1 year of follow-up in the placebo groups of 4 completed clinical studies. We predicted an annual HIV incidence of 3.7% (95% confidence interval: 3.2 to 4.2) among HIV Prevention Trials Network 082 participants in the absence of PrEP and other risk reduction interventions. CONCLUSIONS: We demonstrated the potential of the proposed methodology to provide HIV incidence predictions based on assessment of individual risk behaviors and community and time-specific HIV exposure risk using HIV treatment and viral suppression data. These estimates may serve as comparators in HIV prevention trials without a placebo group.

Journal article

Moore M, Boily M-C, Mitchell KM, Donnell DD, Cohen MS, Dimitrov DTet al., 2020, Identifying regions of greatest need for ending the HIV epidemic: a plan for America, JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 85, Pages: 395-398, ISSN: 1525-4135

BACKGROUND: In the 2019 State of the Union Address, President Trump announced a plan for "Ending the HIV Epidemic" in the United States, with a goal to reduce new HIV infections by 90% by 2030. Phase I of the plan set an intermediate goal of a 75% reduction within 5 years, focusing on select states and counties. METHODS: We assessed the feasibility of the first phase of the plan by estimating the fraction of HIV diagnoses that occur within the targeted region, using a statistical model to predict new HIV cases in each county. We suggested new areas that should be added to the current plan, prioritizing by both a "Density Metric" of new HIV cases and a "Gap Metric" quantifying shortcomings in antiretroviral therapy and pre-exposure prophylaxis uptake. RESULTS: We found the current plan targets less than 60% of new diagnoses. The plan should be expanded to Puerto Rico, Florida, Georgia, Louisiana, and Maryland as well as parts of New York, North Carolina, Texas, and Virginia, areas which were prioritized by both metrics. CONCLUSION: Many of the highest priority areas, both by density of HIV cases and by lack of viral suppression and pre-exposure prophylaxis use, were not covered by the original plan, particularly in the South. The current plan to end the HIV epidemic must be expanded to these areas to feasibly allow for a 75% reduction in new HIV cases within 5 years.

Journal article

Mitchell KM, Dimitrov D, Hughes JP, Moore M, Vittinghoff E, Liu A, Cohen MS, Beyrer C, Donnell D, Boily M-Cet al., 2020, Assessing the use of surveillance data to estimate the impact of prevention interventions on HIV incidence in cluster-randomized controlled trials, Epidemics, Vol: 33, Pages: 1-8, ISSN: 1755-4365

BackgroundIn cluster-randomized controlled trials (C-RCTs) of HIV prevention strategies, HIV incidence is expensive to measure directly. Surveillance data on HIV diagnoses or viral suppression could provide cheaper incidence estimates. We used mathematical modelling to evaluate whether these measures can replace HIV incidence measurement in C-RCTs.MethodsWe used a US HIV transmission model to simulate C-RCTs of expanded antiretroviral therapy(ART), pre-exposure prophylaxis(PrEP) and HIV testing, together or alone. We tested whether modelled reductions in total new HIV diagnoses, diagnoses with acute infection, diagnoses with early infection(CD4 > 500 cells/μl), diagnoses adjusted for testing volume, or the proportion virally non-suppressed, reflected HIV incidence reductions.ResultsOver a two-year trial expanding PrEP alone, modelled reductions in total diagnoses underestimated incidence reductions by a median six percentage points(pp), with acceptable variability(95 % credible interval -14,-2pp). For trials expanding HIV testing alone or alongside ART + PrEP, greater, highly variable bias was seen[-20pp(-128,-1) and -30pp(-134,-16), respectively]. Acceptable levels of bias were only seen over longer trial durations when levels of awareness of HIV-positive status were already high. Expanding ART alone, only acute and early diagnoses reductions reflected incidence reduction well, with some bias[-3pp(-6,-1) and -8pp(-16,-3), respectively]. Early and adjusted diagnoses also reliably reflected incidence when scaling up PrEP alone[bias -5pp(-11,1) and 10pp(3,18), respectively]. For trials expanding testing (alone or with ART + PrEP), bias for all measures explored was too variable for them to replace direct incidence measures, unless using diagnoses when HIV status awareness was already high.ConclusionsSurveillance measures based on HIV diagnoses may sometimes be adequate surrogates for HIV incidence reduction in C-RCTs expanding ART or PrEP only, if adjusted for b

Journal article

Mitchell KM, Dimitrov D, Silhol R, Geidelberg L, Moore M, Liu A, Beyrer C, Mayer KH, Baral S, Boily M-Cet al., 2020, Estimating the potential impact of COVID-19-related disruptions on HIV incidence and mortality among men who have sex with men in the United States: a modelling study., Publisher: Cold Spring Harbor Laboratory

Background: During the COVID-19 pandemic, gay and other men who have sex with men (MSM) in the United States (US) report similar or fewer sexual partners and reduced HIV testing and care access. Pre-exposure prophylaxis (PrEP) use has declined. We estimated the potential impact of COVID-19 on HIV incidence and mortality among US MSM. Methods: We used a calibrated HIV transmission model for MSM in Baltimore, Maryland, and available data on COVID-19-related disruptions to predict impacts of data-driven reductions in sexual partners(0%,25%,50%), condom use(5%), HIV testing(20%), viral suppression(10%), PrEP initiations(72%), PrEP use(9%) and ART initiations(50%), exploring different disruption durations and magnitudes. We estimated the median (95% credible interval) change in cumulative new HIV infections and deaths among MSM over one and five years, compared with a scenario without COVID-19-related disruptions. Findings: A six-month 25% reduction in sexual partners among Baltimore MSM, without HIV service changes, could reduce new HIV infections by 12·2%(11·7,12·8%) and 3·0%(2·6,3·4%) over one and five years, respectively. In the absence of changes in sexual behaviour, the six-month data-driven disruptions to condom use, testing, viral suppression, PrEP initiations, PrEP use and ART initiations combined were predicted to increase new HIV infections by 10·5%(5·8,16·5%) over one year, and by 3·5%(2·1,5·4%) over five years. A 25% reduction in partnerships offsets the negative impact of these combined service disruptions on new HIV infections (overall reduction 3·9%(-1·0,7·4%), 0·0%(-1·4,0·9%) over one, five years, respectively), but not on HIV deaths (corresponding increases 11·0%(6·2,17·7%), 2·6%(1·5,4·3%)). The predicted impacts of reductions in partnerships or viral suppression doubled if they lasted 12

Working paper

Booton RD, Fu G, MacGregor L, Li J, Ong JJ, Tucker JD, Turner KM, Tang W, Vickerman P, Mitchell Ket al., 2020, Estimating the impact of disruptions due to COVID-19 on HIV transmission and control among men who have sex with men in China, Publisher: medRxiv

Introduction The COVID-19 pandemic is impacting HIV care globally, with gaps in HIV treatment expected to increase HIV transmission and HIV-related mortality. We estimated how COVID-19-related disruptions could impact HIV transmission and mortality among men who have sex with men (MSM) in four cities in China. Methods Regional data from China indicated that the number of MSM undergoing facility-based HIV testing reduced by 59% during the COVID-19 pandemic, alongside reductions in ART initiation (34%), numbers of sexual partners (62%) and consistency of condom use (25%). A deterministic mathematical model of HIV transmission and treatment among MSM in China was used to estimate the impact of these disruptions on the number of new HIV infections and HIV-related deaths. Disruption scenarios were assessed for their individual and combined impact over 1 and 5 years for a 3-, 4- or 6-month disruption period. Results Our China model predicted that new HIV infections and HIV-related deaths would be increased most by disruptions to viral suppression, with 25% reductions for a 3-month period increasing HIV infections by 5-14% over 1 year and deaths by 7-12%. Observed reductions in condom use increased HIV infections by 5-14% but had minimal impact (<1%) on deaths. Smaller impacts on infections and deaths (<3%) were seen for disruptions to facility testing and ART initiation, but reduced partner numbers resulted in 11-23% fewer infections and 0.4-1.0% fewer deaths. Longer disruption periods of 4 and 6 months amplified the impact of combined disruption scenarios. When all realistic disruptions were modelled simultaneously, an overall decrease in new HIV infections was always predicted over one year (3-17%), but not over 5 years (1% increase - 4% decrease), while deaths mostly increased over one year (1-2%) and 5 years (1.2 increase - 0.3 decrease). Conclusions The overall impact of COVID-19 on new HIV infections and HIV-related deaths is dependent on the nature, scale and

Working paper

Foss AM, Prudden HJ, Mitchell KM, Pickles M, Washington R, Phillips AE, Alary M, Boily M-C, Moses S, Watts CH, Vickerman PTet al., 2020, Using data from 'visible' populations to estimate the size and importance of 'hidden' populations in an epidemic: A modelling technique., Infectious Disease Modelling, Vol: 5, Pages: 798-813, ISSN: 2468-2152

We used reported behavioural data from cisgender men who have sex with men and transgender women (MSM/TGW) in Bangalore, mainly collected from 'hot-spot' locations that attract MSM/TGW, to illustrate a technique to deal with potential issues with the representativeness of this sample. A deterministic dynamic model of HIV transmission was developed, incorporating three subgroups of MSM/TGW, grouped according to their reported predominant sexual role (insertive, receptive or versatile). Using mathematical modelling and data triangulation for 'balancing' numbers of partners and role preferences, we compared three different approaches to determine if our technique could be useful for inferring characteristics of a more 'hidden' insertive MSM subpopulation, and explored their potential importance for the HIV epidemic. Projections for 2009 across all three approaches suggest that HIV prevalence among insertive MSM was likely to be less than half that recorded in the surveys (4.5-6.5% versus 13.1%), but that the relative size of this subgroup was over four times larger (61-69% of all MSM/TGW versus 15%). We infer that the insertive MSM accounted for 10-20% of all prevalent HIV infections among urban males aged 15-49. Mathematical modelling can be used with data on 'visible' MSM/TGW to provide insights into the characteristics of 'hidden' MSM. A greater understanding of the sexual behaviour of all MSM/TGW is important for effective HIV programming. More broadly, a hidden subgroup with a lower infectious disease prevalence than more visible subgroups, has the potential to contain more infections, if the hidden subgroup is considerably larger in size.

Journal article

Dimitrov D, Moore J, Wood D, Mitchell K, Li M, Hughes J, Donnell D, Mannheimer S, Holtz T, Grant R, Boily MCet al., 2020, Predicted effectiveness of daily and non-daily PrEP for MSM based on sex and pill-taking patterns from HPTN 067/ADAPT, Clinical Infectious Diseases, Vol: 71, Pages: 249-255, ISSN: 1058-4838

Background: HPTN 067/ADAPT evaluated the feasibility of daily and non-daily HIV pre-exposure prophylaxis (PrEP) regimens among high-risk populations, including men who have sex with men (MSM) and transgender women, in Bangkok, Thailand and Harlem, New York, U.S. We used a mathematical model to predict the efficacy and effectiveness of different dosing regimens. Methods: An individual-based mathematical model was used to simulate annual HIV incidence among MSM cohorts. PrEP efficacy for covered sex acts, as defined in the HPTN 067/ADAPT protocol, was estimated using subgroup efficacy estimates from the iPrEx trial. Effectiveness was estimated by comparison of the HIV incidence with and without PrEP use.Results: We estimated that PrEP was highly protective (85%–96% efficacy across regimens and sites) for fully covered acts. PrEP was more protective for partially covered acts in Bangkok (71%–88% efficacy) than in Harlem (62%–81% efficacy). Our model projects 80%, 62%, and 68% effectiveness of daily, time-driven, and event-driven PrEP for MSM in Harlem compared with 90%, 85% and 79% for MSM in Bangkok. Halving the efficacy for partially covered acts decreases effectiveness by 8–9 percentage points in Harlem and by 5–9 percentage points in Bangkok across regimens. Conclusions: Our analysis suggests that PrEP was more effective among MSM in Thailand than in the U.S. as a result of more fully covered sex acts and more pills taken around partially covered acts. Overall, non-daily PrEP was less effective than daily PrEP, especially in the U.S. where the sex act coverage associated with daily use was substantially higher.

Journal article

Silhol R, Boily M-C, Dimitrov D, German D, Flynn C, Farley JE, Gelman M, Hughes JP, Donnell D, Adeyeye A, Remien RH, Beyrer C, Paz-Bailey G, Wejnert C, Mitchell KMet al., 2020, Understanding the HIV epidemic among MSM in Baltimore: a modelling study estimating the impact of past HIV interventions and who acquired and contributed to infections., JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 84, Pages: 253-262, ISSN: 1525-4135

INTRODUCTION: Men who have sex with men (MSM) in the United States (US) are disproportionately affected by HIV. We estimated the impact of past interventions and contribution of different population groups to incident MSM HIV infections. SETTING: Baltimore, US METHODS:: We used a deterministic model, parameterised and calibrated to demographic and epidemic Baltimore MSM data, to estimate the fraction of HIV infections among MSM averted by condoms and antiretroviral therapy (ART) over 1984-2017 and the fraction of infections acquired and transmission contributed by MSM from different demographic groups and disease and care continuum stages over 10-year periods from 1988 to 2017, using population attributable fractions (PAFs). RESULTS: Condom use and ART averted 19% (95% uncertainty interval: 14-25%) and 23% (15-31%) of HIV infections that would have occurred since 1984 and 1996, respectively. Over 2008-2017, 46% (41-52%) of incident infections were acquired by, and 35% (27-49%) of transmissions contributed by MSM aged 18-24 years old (who constitute 27% of all MSM, 19% of HIV+ MSM). MSM with undiagnosed HIV infection, those with diagnosed infection but not in care, and those on ART contributed to 41% (31-54%), 46% (25-56%), and 14% (7-28%) of transmissions, respectively. CONCLUSION: Condoms and ART have modestly impacted the HIV epidemic among Baltimore MSM to date. Interventions reaching MSM with diagnosed infection who are not in care should be implemented since the largest percentage of HIV transmissions among Baltimore MSM are attributed to this group.

Journal article

Stannah J, Dale E, Elmes J, Staunton R, Beyrer C, Mitchell K, Boily M-Cet al., 2019, HIV testing and engagement with the HIV treatment cascade among men who have sex with men in Africa: A systematic review and meta-analysis, Lancet HIV, Vol: 6, Pages: e769-e787, ISSN: 2405-4704

BackgroundHIV disproportionately affects gay, bisexual, and other men who have sex with men (MSM) in Africa, where many countries criminalise same-sex behaviour. We assessed changes in the engagement of African MSM with HIV testing and treatment cascade stages over time, and the influence of anti-LGBT legislation and stigma.MethodsWe systematically searched the peer-reviewed literature to October 10th , 2018 for studies and extracted or derived estimates of HIV testing and/or engagement with the HIV treatment cascade among African MSM from published reports. We derived pooled estimates using inverse-variance random-effects models. We used subgroup and meta-regression analysis to assess associations between testing and status awareness outcomes and study and participant characteristics including the severity of country-level anti-LGBT legislation.FindingsOur searches identified 75 independent eligible studies that provided estimates for 44,993 MSM across one or more of five testing and treatment cascade outcomes. HIV testing increased significantly over time overall, with pooled overall proportions of MSM ever tested of 67·3% (95%Confidence interval 62·1-72·3%,N=44) and tested in the past 12 months of 50·1% (42·4-57·8%,N=31) post-2011 – 14% and 18% points higher than pre-2011, respectively. Post-2011, ever testing was highest in Southern(80·0%) and lowest in Northern(34·4%) and Central(56·1%) Africa, with the greatest increase in Western Africa(from 42·4 to 70·9%). Levels of both testing outcomes and status awareness were statistically significantly lower in countries with the most severe anti-LGBT legislation.Few estimates were available for later stages of the treatment cascade. Available data post61 2011 suggest that the pooled proportion of MSM HIV-positive aware has remained low (18·5%, 12·5-25·3%,N=28) whereas proportions of current ART use were 23·7%

Journal article

Brown P, Tan A-C, El-Esawi MA, Liehr T, Blanck O, Gladue DP, Almeida GMF, Cernava T, Sorzano CO, Yeung AWK, Engel MS, Chandrasekaran AR, Muth T, Staege MS, Daulatabad SV, Widera D, Zhang J, Meule A, Honjo K, Pourret O, Yin C-C, Zhang Z, Cascella M, Flegel WA, Goodyear CS, van Raaij MJ, Bukowy-Bieryllo Z, Campana LG, Kurniawan NA, Lalaouna D, Huttner FJ, Ammerman BA, Ehret F, Cobine PA, Tan E-C, Han H, Xia W, McCrum C, Dings RPM, Marinello F, Nilsson H, Nixon B, Voskarides K, Yang L, Costa VD, Bengtsson-Palme J, Bradshaw W, Grimm DG, Kumar N, Martis E, Prieto D, Sabnis SC, Amer SEDR, Liew AWC, Perco P, Rahimi F, Riva G, Zhang C, Devkota HP, Ogami K, Basharat Z, Fierz W, Siebers R, Tan K-H, Boehme KA, Brenneisen P, Brown JAL, Dalrymple BP, Harvey DJ, Ng G, Werten S, Bleackley M, Dai Z, Dhariwal R, Gelfer Y, Hartmann MD, Miotla P, Tamaian R, Govender P, Gurney-Champion OJ, Kauppila JH, Zhang X, Echeverria N, Subhash S, Sallmon H, Tofani M, Bae T, Bosch O, Cuiv PO, Danchin A, Diouf B, Eerola T, Evangelou E, Filipp FV, Klump H, Kurgan L, Smith SS, Terrier O, Tuttle N, Ascher DB, Janga SC, Schulte LN, Becker D, Browngardt C, Bush SJ, Gaullier G, Ide K, Meseko C, Werner GDA, Zaucha J, Al-Farha AA, Greenwald NF, Popoola SI, Rahman MS, Xu J, Yang SY, Hiroi N, Alper OM, Baker CI, Bitzer M, Chacko G, Debrabant B, Dixon R, Forano E, Gilliham M, Kelly S, Klempnauer K-H, Lidbury BA, Lin MZ, Lynch I, Ma W, Maibach EW, Mather DE, Nandakumar KS, Ohgami RS, Parchi P, Tressoldi P, Xue Y, Armitage C, Barraud P, Chatzitheochari S, Coelho LP, Diao J, Doxey AC, Gobet A, Hu P, Kaiser S, Mitchell KM, Salama MF, Shabalin IG, Song H, Stevanovic D, Yadollahpour A, Zeng E, Zinke K, Alimba CG, Beyene TJ, Cao Z, Chan SS, Gatchell M, Kleppe A, Piotrowski M, Torga G, Woldesemayat AA, Cosacak MI, Haston S, Ross SA, Williams R, Wong A, Abramowitz MK, Effiong A, Lee S, Abid MB, Agarabi C, Alaux C, Albrecht DR, Atkins GJ, Beck CR, Bonvin AMJJ, Bourke E, Brand T, Braun RJ, Bull JA, Cardoso P, Carter Det al., 2019, Large expert-curated database for benchmarking document similarity detection in biomedical literature search, Database: the journal of biological databases and curation, Vol: 2019, Pages: 1-66, ISSN: 1758-0463

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.

Journal article

Wong NS, Chan KCW, Wong BCK, Leung CC, Chan WK, Lin AWC, Lui GCY, Mitchell KM, Lee SSet al., 2019, Latent tuberculosis infection testing strategies for HIV-positive individuals in Hong Kong., JAMA Network Open, Vol: 2, Pages: 1-12, ISSN: 2574-3805

Importance: With immune recovery following early initiation of antiretroviral therapy (ART), the risk of tuberculosis (TB) reactivation among individuals with HIV could be reduced. The current strategy of annual latent TB infection (LTBI) testing should be revisited to increase cost-effectiveness and reduce the intensity of testing for individuals. Objective: To analyze the cost-effectiveness of LTBI testing strategies for individuals in Hong Kong with HIV who had negative LTBI test results at baseline. Design, Setting, and Participants: This decision analytical model study using a cost-effectiveness analysis included 3130 individuals with HIV in Hong Kong, China, which has an intermediate TB burden and a low incidence of HIV-TB coinfection. A system dynamics model of individuals with HIV attending a major HIV specialist clinic in Hong Kong was developed and parameterized by longitudinal clinical and LTBI testing records of patients during a 15-year period. The study population was stratified by age group, CD4 lymphocyte level, ART status, and right of abode. Alternative strategies for LTBI testing after a baseline test were compared with annual testing under different coverages of ART, LTBI testing, and LTBI treatment scenarios in the model. An annual discounting rate of 3.5% was used in cost-effectiveness analysis. Main Outcomes and Measures: Proportion of new TB cases averted above base case scenario, discounted quality-adjusted life-years gained (QALYG), incremental cost, and incremental cost-effectiveness ratios in 2017 to 2023. Results: A total of 3130 patients with HIV (2740 [87.5%] male and 2800 [89.5%] younger than 50 years at HIV diagnosis) with 16 630 person-years of follow-up data from 2002 to 2017 were analyzed. Of these, 94 patients (0.67 [95% CI, 0.51-0.91] per 100 person-years) developed TB. Model estimates of cumulative number of TB cases would reach 146 by 2023, with the annual number of new TB diagnoses ranging from 6 to 8. For patients who had ne

Journal article

Shacklett BL, Blanco J, Hightow-Weidman L, Mgodi N, Alcami J, Buchbinder S, Chirenje M, Dabee S, Diallo M, Dumchev K, Herrera C, Levy ME, Martin-Gayo E, Makoah NA, Mitchell KM, Mugwanya K, Reddy K, Rodríguez ML, Rodriguez-Garcia M, Shover CL, Shrivastava T, Tomaras GD, Van Diepen M, Walia M, Warren M, Manrique A, Thyagarajan B, Torri Tet al., 2019, HIV Research for Prevention 2018: From research to impact: Conference summary and highlights, AIDS Research and Human Retroviruses, Vol: 35, Pages: 598-607, ISSN: 0889-2229

The HIV Research for Prevention (HIVR4P) conference is dedicated to advancing HIV prevention research, responding to a growing consensus that effective and durable prevention will require a combination of approaches as well as unprecedented collaboration among scientists, practitioners, and community workers from different fields and geographic areas. The conference theme in 2018, “From Research to Impact,” acknowledged an increasing focus on translation of promising research findings into practical, accessible, and affordable HIV prevention options for those who need them worldwide. HIVR4P 2018 was held in Madrid, Spain, on 21–25 October, with >1,400 participants from 52 countries around the globe, representing all aspects of HIV prevention research and implementation. The program included 137 oral and 610 poster presentations. This article presents a brief summary of highlights from the conference. More detailed information, complete abstracts as well as webcasts and daily Rapporteur summaries may be found on the conference website.

Journal article

Mitchell KM, Hoots B, German D, FLynn C, Farley J, Gelman M, Hughes J, DOnnell D, Adeyeye A, Remien R, Beyrer C, Paz Bailey G, Boily M-Cet al., 2019, Improvements in the HIV care continuum needed to meaningfully reduce HIV incidence among men who have sex with men in Baltimore, US: a modelling study for HPTN 078, Journal of the International AIDS Society, Vol: 22, ISSN: 1758-2652

Introduction HIV prevalence is high among men who have sex with men (MSM) in Baltimore, Maryland, United States, and levels of viral suppression among HIV-positive MSM are relatively low. The HIV Prevention Trials Network (HPTN) 078 trial seeks to increase levels of viral suppression among US MSM by increasing rates of diagnosis and linkage to care and treatment. We estimated the increases in viral suppression needed to reach different HIV incidence reduction targets, and the impact of meeting diagnosis and treatment targets.Methods: We used a mathematical model of HIV transmission among MSM from Baltimore, US, parameterised with behavioural data and fitted to HIV prevalence and care continuum data for Baltimore wherever possible, to project increases in viral suppression needed to reduce the HIV incidence rate among Baltimore MSM by 10, 20, 30, or 50% after 2, 5, and 10 years. We also projected HIV incidence reductions achieved if US national targets – 90% of people living with HIV (PLHIV) know their HIV serostatus, 90% of those diagnosed are retained in HIV medical care and 80% of those diagnosed are virally suppressed - or UNAIDS 90-90-90 targets (90% of PLHIV know their status, 90% of those diagnosed receive antiretroviral therapy (ART), 90% of those receiving ART are virally suppressed) are each met by 2020.Results: To reduce the HIV incidence rate by 20% and 50% after 5 years (compared with the base-case at the same time point), the proportion of all HIV-positive MSM who are virally suppressed must increase above 2015 levels by a median 13 percentage points (95% uncertainty interval 9-16 percentage points) from median 49% to 60%, and 27 percentage points (22-35) from 49% to 75%, respectively. Meeting all three US or 90-90-90 UNAIDS targets results in a 48% (31-63%) and 51% (38-65%) HIV incidence rate reduction in 2020, respectively. Conclusions: Substantial improvements in levels of viral suppression will be needed to achieve significant incidence reduct

Journal article

Stannah J, Dale E, Elmes J, Staunton R, Boily M-C, Mitchell KMet al., 2018, Sub-optimal Engagement of African MSM in the HIV Treatment Cascade: A Systematic Review and Meta-analysis, HIV Research for Prevention Meeting (HIVR4P) - AIDS Vaccine, Microbicide and ARV-Based Prevention Science, Publisher: MARY ANN LIEBERT, INC, Pages: 404-404, ISSN: 0889-2229

Conference paper

Silhol R, Boily M-C, Dimitrov D, German D, Flynn C, Farley JE, Gelman M, Hughes JP, Donnell D, Adeyeye A, Remien RH, Beyrer C, Paz-Bailey G, Wejnert C, Mitchell KMet al., 2018, Understanding HIV Transmission Dynamics and the Impact of Past HIV Interventions Among MSM in Baltimore: A Modelling Study for HPTN 078, HIV Research for Prevention Meeting (HIVR4P) - AIDS Vaccine, Microbicide and ARV-Based Prevention Science, Publisher: MARY ANN LIEBERT, INC, Pages: 283-283, ISSN: 0889-2229

Conference paper

Tang W, Wei C, Cao B, Wu D, Li KT, Lu H, Ma W, Kang D, Li H, Liao M, Mollan KR, Hudgens MG, Liu C, Huang W, Liu A, Zhang Y, Smith MK, Mitchell KM, Ong JJ, Fu H, Vickerman P, Yang L, Wang C, Zheng H, Yang B, Tucker JDet al., 2018, Crowdsourcing to expand HIV testing among men who have sex with men in China: A closed cohort stepped wedge cluster randomized controlled trial, PLOS MEDICINE, Vol: 15, ISSN: 1549-1676

BackgroundHIV testing rates are suboptimal among at-risk men. Crowdsourcing may be a useful tool for designing innovative, community-based HIV testing strategies to increase HIV testing. The purpose of this study was to use a stepped wedge cluster randomized controlled trial (RCT) to evaluate the effect of a crowdsourced HIV intervention on HIV testing uptake among men who have sex with men (MSM) in eight Chinese cities.Methods and findingsAn HIV testing intervention was developed through a national image contest, a regional strategy designathon, and local message contests. The final intervention included a multimedia HIV testing campaign, an online HIV testing service, and local testing promotion campaigns tailored for MSM. This intervention was evaluated using a closed cohort stepped wedge cluster RCT in eight Chinese cities (Guangzhou, Shenzhen, Zhuhai, and Jiangmen in Guangdong province; Jinan, Qingdao, Yantai, and Jining in Shandong province) from August 2016 to August 2017. MSM were recruited through Blued, a social networking mobile application for MSM, from July 29 to August 21 of 2016. The primary outcome was self-reported HIV testing in the past 3 months. Secondary outcomes included HIV self-testing, facility-based HIV testing, condom use, and syphilis testing. Generalized linear mixed models (GLMMs) were used to analyze primary and secondary outcomes. We enrolled a total of 1,381 MSM. Most were ≤30 years old (82%), unmarried (86%), and had a college degree or higher (65%). The proportion of individuals receiving an HIV test during the intervention periods within a city was 8.9% (95% confidence interval [CI] 2.2–15.5) greater than during the control periods. In addition, the intention-to-treat analysis showed a higher probability of receiving an HIV test during the intervention periods as compared to the control periods (estimated risk ratio [RR] = 1.43, 95% CI 1.19–1.73). The intervention also increased HIV self-testing (RR = 1.89, 95% CI 1

Journal article

Mitchell KM, Dimitrov D, Hughes J, Xia F, Donnell D, Amico R, Bokock K, CHITWARAKORN A, Bekker L-G, Holtz T, Mannheimer S, Grant R, Boily MCet al., 2018, In what circumstances could non-daily pre-exposure prophylaxis for HIV substantially reduce program costs?, AIDS, Vol: 32, Pages: 809-818, ISSN: 0269-9370

Objectives:To review the main factors influencing the costs of nondaily oral pre-exposure prophylaxis (PrEP) with tenofovir ( emtricitabine). To estimate the costreductions possible with nondaily PrEP compared with daily PrEP for different popula-tions (MSM and heterosexual populations).Design:Systematic review and data triangulation.Methods:We estimated the required number of tablets/person/week for dosing regi-mens used in the HPTN 067/ADAPT (daily/time-driven/event-driven) and IPERGAY (on-demand) trials for different patterns of sexual intercourse. Using trial data, andbehavioural and cost data obtained through systematic literature reviews, we estimatedcost savings resulting from tablet reductions for nondaily versus daily oral PrEP,assuming 100% adherence.Results:Among different populations being prioritized for PrEP, the median reportednumber of days of sexual activity varied between 0 and 2days/week (0–1.5days/weekfor MSM, 1–2days/week for heterosexual populations). With 100% adherence and twoor fewer sex-days/week, HPTN 067/ADAPT nondaily regimens reduced the number oftablets/week by more than 40% compared with daily PrEP. PrEP program costs werereduced the most in settings with high drug costs, for example, by 66–69% with event-driven PrEP for French/US populations reporting on average one sex-day/week.Conclusion:Nondaily oral PrEP could lower costs substantially (>50%) compared withdaily PrEP, particularly in high-income countries. Adherence and efficacy data areneeded to determine cost-effectiveness.

Journal article

Sucharitakul K, Boily MC, Dimitrov D, Mitchell Ket al., 2018, Influence of model assumptions about HIV disease progression after initiating or stopping treatment on estimates of infections and deaths averted by scaling up antiretroviral therapy, PLoS ONE, Vol: 13, ISSN: 1932-6203

BackgroundMany mathematical models have investigated the population-level impact of expanding antiretroviral therapy (ART), using different assumptions about HIV disease progression on ART and among ART dropouts. We evaluated the influence of these assumptions on model projections of the number of infections and deaths prevented by expanded ART.MethodsA new dynamic model of HIV transmission among men who have sex with men (MSM) was developed, which incorporated each of four alternative assumptions about disease progression used in previous models: (A) ART slows disease progression; (B) ART halts disease progression; (C) ART reverses disease progression by increasing CD4 count; (D) ART reverses disease progression, but disease progresses rapidly once treatment is stopped. The model was independently calibrated to HIV prevalence and ART coverage data from the United States under each progression assumption in turn. New HIV infections and HIV-related deaths averted over 10 years were compared for fixed ART coverage increases.ResultsLittle absolute difference (<7 percentage points (pp)) in HIV infections averted over 10 years was seen between progression assumptions for the same increases in ART coverage (varied between 33% and 90%) if ART dropouts reinitiated ART at the same rate as ART-naïve MSM. Larger differences in the predicted fraction of HIV-related deaths averted were observed (up to 15pp). However, if ART dropouts could only reinitiate ART at CD4<200 cells/μl, assumption C predicted substantially larger fractions of HIV infections and deaths averted than other assumptions (up to 20pp and 37pp larger, respectively).ConclusionDifferent disease progression assumptions on and post-ART interruption did not affect the fraction of HIV infections averted with expanded ART, unless ART dropouts only re-initiated ART at low CD4 counts. Different disease progression assumptions had a larger influence on the fraction of HIV-related deaths averted with expande

Journal article

de Montigny S, Boily M, Masse BM, Mitchell KM, Dimitrov Det al., 2018, Assessing the utility of the tipping point ratio to monitor HIV treatment programmes in the era of universal access to ART., Infectious Disease Modelling, Vol: 3, Pages: 85-96, ISSN: 2468-0427

BackgroundThe epidemiological tipping point ratio (TPR) has been suggested as a useful indicator to monitor the scale-up of antiretroviral treatment (ART) programmes and determine when scale-up is sufficient to control the epidemic. TPR has been defined as the ratio of yearly number of new HIV infections to the yearly number of new ART initiations or to the yearly net increase in the number of people on ART. It has been used to rank the progress of treatment programmes across countries, with the objective of reaching a TPR value under 1. Our study aims to assess if TPR alone can be used as an indicator of ART success across settings by comparing the expected changes in HIV incidence and ART coverage when TPR is maintained constant over time. In particular, we focus on the effect of ART initiation timing (emphasis on ART being initiated early or late during HIV progression) on the interpretation of the TPR.MethodsWe used a dynamic model of HIV transmission in South Africa representing ART rollout leading to universal treatment in 2017. The model is calibrated to HIV incidence, HIV prevalence and ART coverage in 2012 in South Africa, and 1000 simulations are selected for the base-case scenario. To measure the effect of TPR, we simulate TPR-preserving interventions, maintaining TPR (yearly number of new ART initiations denominator) at the value observed in 2019 (between 0.65 and 1.25) for 15 years. We compare ART coverage and HIV incidence across TPR values and across strategies in which ART access is prioritized differently. In a secondary analysis, we illustrate the sensitivity of new ART initiations to ART retention, and we compare both definitions of the TPR.ResultsOur analysis shows that HIV incidence reduction is weakly correlated to TPR: the same reduction in HIV incidence (15%) can be achieved by implementing the same strategy with a wide range of TPR maintained (0.65–1.12). Assuming high retention in ART, TPR-preserving strategies prioritizing early ART

Journal article

Mitchell KM, Hoots B, Dimitrov D, Farley J, Gelman M, German D, Flynn C, Adeyeye A, Remien RH, Beyrer C, Paz-Bailey G, Boily M-Cet al., 2016, Potential Impact on HIV Incidence of Increasing Viral Suppression among HIV-positive MSM in Baltimore: Mathematical Modelling for HPTN 078, Conference on HIV Research for Prevention (HIV R4P), Publisher: Mary Ann Liebert, Pages: 64-64, ISSN: 1931-8405

Conference paper

Dimitrov D, Wood D, Mitchell KM, Li M, Hughes JP, Donnell D, Bekker L-G, Mannheimer S, Holtz TH, Grant RM, Boily M-Cet al., 2016, Predicted Effectiveness of Daily and Non-daily PrEP Based on Sex Coverage Data from HPTN 067 ADAPT Sites in South Africa, Thailand and US, Conference on HIV Research for Prevention (HIV R4P), Publisher: MARY ANN LIEBERT, INC, Pages: 298-298, ISSN: 0889-2229

Conference paper

Mitchell KM, Prudden HJ, Washington R, Isac S, Rajaram SP, Foss AM, Terris-Prestholt F, Boily MC, Vickerman Pet al., 2016, Potential impact of pre-exposure prophylaxis for female sex workers and men who have sex with men in Bangalore, India: a mathematical modelling study, Journal of the International AIDS Society, Vol: 19, ISSN: 1758-2652

Introduction: In Bangalore, new HIV infections of female sex workers and men who have sex with men continue to occur, despite high condom use. Pre-exposure prophylaxis (PrEP) has high anti-HIV efficacy for men who have sex with men. PrEP demonstration projects are underway amongst Indian female sex workers. We estimated the impact and efficiency of prioritising PrEP to female sex workers and/or men who have sex with men in Bangalore.Methods: A mathematical model of HIV transmission and treatment for female sex workers, clients, men who have sex with men and low-risk groups was parameterised and fitted to Bangalore data. The proportion of transmission attributable (population attributable fraction) to commercial sex and sex between men was calculated. PrEP impact (infections averted, life years gained) and efficiency (life years gained/infections averted per 100 person years on PrEP) were estimated for different levels of PrEP adherence, coverage and prioritisation strategies (female sex workers, high-risk men who have sex with men, both female sex workers and high-risk men who have sex with men, or female sex workers with lower condom use), under current conditions and in a scenario with lower baseline condom use amongst key populations. Results: Population attributable fractions for commercial sex and sex between men have declined over time, and they are predicted to account for 19% of all new infections between 2016 and 2025. PrEP could prevent a substantial proportion of infections amongst female sex workers and men who have sex with men in this setting (23%/27% over 5/10 years, with 60% coverage and 50% adherence), which could avert 2.9%/4.3% of infections over 5/10 years in the whole Bangalore population. Impact and efficiency in the whole population was greater if female sex workers were prioritised. Efficiency increased, but impact decreased, if only female sex workers with lower condom use were given PrEP. Greater impact and efficiency was predicted for the

Journal article

Mukandavire Z, Mitchell KM, Vickerman P, 2015, Comparing the impact of increasing condom use or HIV pre-exposure prophylaxis (PrEP) use among female sex workers, Epidemics, Vol: 14, Pages: 62-70, ISSN: 1878-0067

In many settings, interventions targeting female sex workers (FSWs) could significantly reduce the overall transmission of HIV. To understand the role HIV pre-exposure prophylaxis (PrEP) could play in controlling HIV transmission amongst FSWs, it is important to understand how its impact compares with scaling-up condom use—one of the proven HIV prevention strategies for FSWs. It is important to remember that condoms also have other benefits such as reducing the incidence of sexually transmitted infections and preventing pregnancy. A dynamic deterministic model of HIV transmission amongst FSWs, their clients and other male partners (termed ‘pimps’) was used to compare the protection provided by PrEP for HIV-negative FSWs with FSWs increasing their condom use with clients and/or pimps. For different HIV prevalence scenarios, levels of pimp interaction, and baseline condom use, we estimated the coverage of PrEP that gives the same reduction in endemic FSW HIV prevalence or HIV infections averted as different increases in condom use. To achieve the same impact on FSW HIV prevalence as increasing condom use by 1%, the coverage of PrEP has to increase by >2%. The relative impact of PrEP increases for scenarios where pimps contribute to HIV transmission, but not greatly, and decreases with higher baseline condom use. In terms of HIV infections averted over 10 years, the relative impact of PrEP compared to condoms was reduced, with a >3% increase in PrEP coverage achieving the same impact as a 1% increase in condom use. Condom promotion interventions should remain the mainstay HIV prevention strategy for FSWs, with PrEP only being implemented once condom interventions have been maximised or to fill prevention gaps where condoms cannot be used.

Journal article

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