Imperial College London

ProfessorMarie-ClaudeBoily

Faculty of MedicineSchool of Public Health

Professor of Mathematical Epidemiology
 
 
 
//

Contact

 

+44 (0)20 7594 3263mc.boily

 
 
//

Location

 

LG26Norfolk PlaceSt Mary's Campus

//

Summary

 

Publications

Publication Type
Year
to

229 results found

Beyrer C, Crago A-L, Bekker L-G, Butler J, Shannon K, Kerrigan D, Decker MR, Baral SD, Poteat T, Wirtz AL, Weir BW, Barre-Sinoussi F, Kazatchkine M, Sidibe M, Dehne K-L, Boily M-C, Strathdee SAet al., 2015, An action agenda for HIV and sex workers, LANCET, Vol: 385, Pages: 287-301, ISSN: 0140-6736

Journal article

Shannon K, Strathdee SA, Goldenberg SM, Duff P, Mwangi P, Rusakova M, Reza-Paul S, Lau J, Deering K, Pickles MR, Boily M-Cet al., 2015, Global epidemiology of HIV among female sex workers: influence of structural determinants, LANCET, Vol: 385, Pages: 55-71, ISSN: 0140-6736

Journal article

Malagon T, Drolet M, Boily M-C, Laprise J-F, Brisson Met al., 2015, Changing Inequalities in Cervical Cancer: Modeling the Impact of Vaccine Uptake, Vaccine Herd Effects, and Cervical Cancer Screening in the Post-Vaccination Era, CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION, Vol: 24, Pages: 276-285, ISSN: 1055-9965

Journal article

Mitchell KM, Foss AM, Ramesh BM, Washington R, Isac S, Prudden HJ, Deering KN, Blanchard JF, Moses S, Lowndes CM, Boily M-C, Alary M, Vickerman Pet al., 2014, Relationship between exposure to the Avahan intervention and levels of reported condom use among men who have sex with men in southern India, BMC Public Health, Vol: 14, ISSN: 1471-2458

BackgroundThe Avahan intervention promotes consistent (100%) condom use amongst men who have sex with men in southern India. We assessed how condom use varies with intervention exposure for men who have sex with men in Bangalore.MethodsSelf-reported condom use and intervention exposure data were derived from a cross-sectional survey. Consistent condom use and condom use at last sex act with all, main, and casual male sex partners were assessed. Binary and continuous variables reflecting intervention exposure (including contact(s) with intervention staff, receiving condoms and seeing condom demonstrations) were used. Multivariable logistic regression was employed to assess the relationship between condom use with each type of partner and each exposure variable independently, controlling for socio-demographic and behavioural factors associated with condom use or intervention exposure.ResultsCondom use with all partners was higher among those who had ever been contacted by, received condoms from, or seen a condom demonstration by intervention staff (adjusted odds ratio >2, p < 0.02 for all). Consistent condom use with all types of partner increased with the number of condom demonstrations seen in the last month (adjusted odds ratio = 2.1 per demonstration, p < 0.025), while condom use at last sex act with a casual (but not main) partner increased with the number of condoms received from the intervention (adjusted odds ratio = 1.4 per condom, p = 0.04).ConclusionsDirect contact with Avahan program staff is associated with increased reported condom use among men who have sex with men in Bangalore. Reported consistent condom use and condom use at last sex act are associated with contacts involving demonstrations of correct condom use, and with receiving condoms, respectively.Keywords: Consistent condom use; Condom use at last sex act; Condom demonstration; Key population; Bangalore; Cross-secti

Journal article

Vassall A, Chandrashekar S, Pickles M, Beattie TS, Shetty G, Bhattacharjee P, Boily M-C, Vickerman P, Bradley J, Alary M, Moses S, CHARME India Group, Watts Cet al., 2014, Community mobilisation and empowerment interventions as part of HIV prevention for female sex workers in southern India: a cost-effectiveness analysis, PLOS One, Vol: 9, ISSN: 1932-6203

BackgroundMost HIV prevention for female sex workers (FSWs) focuses on individual behaviour change involving peer educators, condom promotion and the provision of sexual health services. However, there is a growing recognition of the need to address broader societal, contextual and structural factors contributing to FSW risk behaviour. We assess the cost-effectiveness of adding community mobilisation (CM) and empowerment interventions (eg. community mobilisation, community involvement in programme management and services, violence reduction, and addressing legal policies and police practices), to core HIV prevention services delivered as part of Avahan in two districts (Bellary and Belgaum) of Karnataka state, Southern India.MethodsAn ingredients approach was used to estimate economic costs in US$ 2011 from an HIV programme perspective of CM and empowerment interventions over a seven year period (2004–2011). Incremental impact, in terms of HIV infections averted, was estimated using a two-stage process. An ‘exposure analysis’ explored whether exposure to CM was associated with FSW’s empowerment, risk behaviours and HIV/STI prevalence. Pathway analyses were then used to estimate the extent to which behaviour change may be attributable to CM and to inform a dynamic HIV transmission model.FindingsThe incremental costs of CM and empowerment were US$ 307,711 in Belgaum and US$ 592,903 in Bellary over seven years (2004–2011). Over a 7-year period (2004–2011) the mean (standard deviation, sd.) number of HIV infections averted through CM and empowerment is estimated to be 1257 (308) in Belgaum and 2775 (1260) in Bellary. This translates in a mean (sd.) incremental cost per disability adjusted life year (DALY) averted of US$ 14.12 (3.68) in Belgaum and US$ 13.48 (6.80) for Bellary - well below the World Health Organisation recommended willingness to pay threshold for India. When savings from ART are taken into account, investments in CM an

Journal article

Laprise J-F, Drolet M, Boily M-C, Jit M, Sauvageau C, Franco EL, Lemieux-Mellouki P, Malagon T, Brisson Met al., 2014, Comparing the cost-effectiveness of two- and three-dose schedules of human papillomavirus vaccination: A transmission-dynamic modelling study, VACCINE, Vol: 32, Pages: 5845-5853, ISSN: 0264-410X

Journal article

Panovska-Griffiths J, Vassall A, Prudden HJ, Lepine A, Boily M-C, Chandrashekar S, Mitchell K, Beattie TS, Alary M, Martin NK, Vickerman Pet al., 2014, Optimal allocation of resources in female sex worker targeted HIV prevention interventions: Model insights from Avahan in South India, PLOS One, Vol: 9, ISSN: 1932-6203

BackgroundThe Avahan programme has provided HIV prevention activities, including condom promotion, to female sex workers (FSWs) in southern India since 2004. Evidence suggests Avahan averted 202,000 HIV infections over 4 years. For replicating this intervention elsewhere, it is essential to understand how the intervention’s impact could have been optimised for different budget levels.MethodsBehavioural data were used to determine how condom use varied for FSWs with different levels of intervention intensity. Cost data from 64 Avahan districts quantified how district-level costs related to intervention scale and intensity. A deterministic model for HIV transmission amongst FSWs and clients projected the impact and cost of intervention strategies for different scale and intensity, and identified the optimal strategies that maximise impact for different budget levels.ResultsAs budget levels increase, the optimal intervention strategy is to first increase intervention intensity which achieves little impact, then scale-up coverage to high levels for large increases in impact, and lastly increase intensity further for small additional gains. The cost-effectiveness of these optimal strategies generally improves with increasing resources, while straying from these strategies can triple costs for the same impact. Projections suggest Avahan was close to being optimal, and moderate budget reductions (≥20%) would have reduced impact considerably (>40%).DiscussionOur analysis suggests that tailoring the design of HIV prevention programmes for FSWs can improve impact, and that a certain level of resources are required to achieve demonstrable impact. These insights are critical for optimising the use of limited resources for preventing HIV.

Journal article

Mountain E, Pickles M, Mishra S, Vickerman P, Alary M, Boily M-Cet al., 2014, The HIV care cascade and antiretroviral therapy in female sex workers: implications for HIV prevention, EXPERT REVIEW OF ANTI-INFECTIVE THERAPY, Vol: 12, Pages: 1203-1219, ISSN: 1478-7210

Journal article

Mountain E, Mishra S, Vickerman P, Pickles M, Gilks C, Boily M-Cet al., 2014, Antiretroviral therapy uptake, attrition, adherence and outcomes among HIB-infected female sex workers: a systematic review and meta-analysis, PLOS One, Vol: 9, ISSN: 1932-6203

PurposeWe aimed to characterize the antiretroviral therapy (ART) cascade among female sex workers (FSWs) globally.MethodsWe systematically searched PubMed, Embase and MEDLINE in March 2014 to identify studies reporting on ART uptake, attrition, adherence, and outcomes (viral suppression or CD4 count improvements) among HIV-infected FSWs globally. When possible, available estimates were pooled using random effects meta-analyses (with heterogeneity assessed using Cochran's Q test and I2 statistic).Results39 studies, reporting on 21 different FSW study populations in Asia, Africa, North America, South America, and Central America and the Caribbean, were included. Current ART use among HIV-infected FSWs was 38% (95% CI: 29%–48%, I2 = 96%, 15 studies), and estimates were similar between high-, and low- and middle-income countries. Ever ART use among HIV-infected FSWs was greater in high-income countries (80%; 95% CI: 48%–94%, I2 = 70%, 2 studies) compared to low- and middle-income countries (36%; 95% CI: 7%–81%, I2 = 99%, 3 studies). Loss to follow-up after ART initiation was 6% (95% CI: 3%–11%, I2 = 0%, 3 studies) and death after ART initiation was 6% (95% CI: 3%–11%, I2 = 0%, 3 studies). The fraction adherent to ≥95% of prescribed pills was 76% (95% CI: 68%–83%, I2 = 36%, 4 studies), and 57% (95% CI: 46%–68%, I2 = 82%, 4 studies) of FSWs on ART were virally suppressed. Median gains in CD4 count after 6 to 36 months on ART, ranged between 103 and 241 cells/mm3 (4 studies).ConclusionsDespite global increases in ART coverage, there is a concerning lack of published data on HIV treatment for FSWs. Available data suggest that FSWs can achieve levels of ART uptake, retention, adherence, and treatment response comparable to that seen among women in the general population, but these data are from only a few research settings. More routine programme data on HIV treatment among FSWs across settings should be collected and disseminated

Journal article

Vassall A, Pickles M, Chandrashekar S, Boily M-C, Shetty G, Guinness L, Lowndes CM, Bradley J, Moses S, Alary M, Vickerman Pet al., 2014, Cost-effectiveness of HIV prevention for high-risk groups at scale: an economic evaluation of the Avahan programme in south India, LANCET GLOBAL HEALTH, Vol: 2, Pages: E531-E540, ISSN: 2214-109X

Journal article

Mitchell KM, Foss AM, Prudden HJ, Mukandavire Z, Pickles M, Williams JR, Johnson HC, Ramesh BM, Washington R, Isac S, Rajaram S, Phillips AE, Bradley J, Alary M, Moses S, Lowndes CM, Watts CH, Boily M-C, Vickerman Pet al., 2014, Who mixes with whom among men who have sex with men? Implications for modelling the HIV epidemic in southern India, Journal of Theoretical Biology, Vol: 355, Pages: 140-150, ISSN: 1095-8541

In India, the identity of men who have sex with men (MSM) is closely related to the role taken in anal sex(insertive, receptive or both), but little is known about sexual mixing between identity groups. Both rolesegregation (taking only the insertive or receptive role) and the extent of assortative (within-group)mixing are known to affect HIV epidemic size in other settings and populations. This study explores howdifferent possible mixing scenarios, consistent with behavioural data collected in Bangalore, south India,affect both the HIV epidemic, and the impact of a targeted intervention. Deterministic models describingHIV transmission between three MSM identity groups (mostly insertive Panthis/Bisexuals, mostlyreceptive Kothis/Hijras and versatile Double Deckers), were parameterised with behavioural data fromBangalore. We extended previous models of MSM role segregation to allow each of the identity groups tohave both insertive and receptive acts, in differing ratios, in line with field data. The models were used toexplore four different mixing scenarios ranging from assortative (maximising within-group mixing) todisassortative (minimising within-group mixing). A simple model was used to obtain insights into therelationship between the degree of within-group mixing, R0 and equilibrium HIV prevalence underdifferent mixing scenarios. A more complex, extended version of the model was used to compare the predicted HIV prevalence trends and impact of an HIV intervention when fitted to data from Bangalore.With the simple model, mixing scenarios with increased amounts of assortative (within-group) mixingtended to give rise to a higher R0 and increased the likelihood that an epidemic would occur. When thecomplex model was fit to HIV prevalence data, large differences in the level of assortative mixing wereseen between the fits identified using different mixing scenarios, but little difference was projected infuture HIV prevalence trends. An oral pre-exposure prophylaxis (P

Journal article

Williams JR, Alary M, Lowndes CM, Behanzin L, Labbe A-C, Anagonou S, Ndour M, Minani I, Ahoussinou C, Zannou DM, Boily M-Cet al., 2014, Positive Impact of Increases in Condom Use among Female Sex Workers and Clients in a Medium HIV Prevalence Epidemic: Modelling Results from Project SIDA1/2/3 in Cotonou, Benin, PLOS One, Vol: 9, ISSN: 1932-6203

BackgroundA comprehensive, HIV prevention programme (Projet Sida1/2/3) was implemented among female sex workers (FSWs) in Cotonou, Benin, in 1993 following which condom use among FSWs increased threefold between 1993 and 2008 while FSW HIV prevalence declined from 53.3% to 30.4%.ObjectiveEstimate the potential impact of the intervention on HIV prevalence/incidence in FSWs, clients and the general population in Cotonou, Benin.Methods and FindingsA transmission dynamics model parameterised with setting-specific bio-behavioural data was used within a Bayesian framework to fit the model and simulate HIV transmission in the high and low-risk population of Cotonou and to estimate HIV incidence and infections averted by SIDA1/2/3. Our model results suggest that prior to SIDA1/2/3 commercial sex had contributed directly or indirectly to 93% (84–98%) of all cumulative infections and that the observed decline in FSWs HIV prevalence was more consistent with the self-reported post-intervention increase in condom use by FSWs than a counterfactual assuming no change in condom use after 1993 (CF-1). Compared to the counterfactual (CF-1), the increase in condom use may have prevented 62% (52–71%) of new HIV infections among FSWs between 1993 and 2008 and 33% (20–46%) in the overall population.ConclusionsOur analysis provides plausible evidence that the post-intervention increase in condom use during commercial sex significantly reduced HIV prevalence and incidence among FSWs and general population. Sex worker interventions can be effective even in medium HIV prevalence epidemics and need to be sustained over the long-term.

Journal article

Mishra S, Pickles M, Blanchard JF, Moses S, Shubber Z, Boily M-Cet al., 2014, Validation of the Modes of Transmission Model as a Tool to Prioritize HIV Prevention Targets: A Comparative Modelling Analysis, PLOS ONE, Vol: 9, ISSN: 1932-6203

Journal article

Shubber Z, Mishra S, Vesga JF, Boily M-Cet al., 2014, The HIV Modes of Transmission model: a systematic review of its findings and adherence to guidelines, Journal of the International AIDS Society, Vol: 17, ISSN: 1758-2652

Introduction: The HIV Modes of Transmission (MOT) model estimates the annual fraction of new HIV infections (FNI) acquired by different risk groups. It was designed to guide country-specific HIV prevention policies. To determine if the MOT produced context-specific recommendations, we analyzed MOT results by region and epidemic type, and explored the factors (e.g. data used to estimate parameter inputs, adherence to guidelines) influencing the differences.Methods: We systematically searched MEDLINE, EMBASE and UNAIDS reports, and contacted UNAIDS country directors for published MOT results from MOT inception (2003) to 25 September 2012.Results: We retrieved four journal articles and 20 UNAIDS reports covering 29 countries. In 13 countries, the largest FNI (range 26 to 63%) was acquired by the low-risk group and increased with low-risk population size. The FNI among female sex workers (FSWs) remained low (median 1.3%, range 0.04 to 14.4%), with little variability by region and epidemic type despite variability in sexual behaviour. In India and Thailand, where FSWs play an important role in transmission, the FNI among FSWs was 2 and 4%, respectively. In contrast, the FNI among men who have sex with men (MSM) varied across regions (range 0.1 to 89%) and increased with MSM population size. The FNI among people who inject drugs (PWID, range 0 to 82%) was largest in early-phase epidemics with low overall HIV prevalence. Most MOT studies were conducted and reported as per guidelines but data quality remains an issue.Conclusions: Although countries are generally performing the MOT as per guidelines, there is little variation in the FNI (except among MSM and PWID) by region and epidemic type. Homogeneity in MOT FNI for FSWs, clients and low-risk groups may limit the utility of MOT for guiding country-specific interventions in heterosexual HIV epidemics.

Journal article

Jit M, Choi YH, Laprise J-F, Boily M-C, Drolet M, Brisson Met al., 2014, Two-dose strategies for human papillomavirus vaccination: How well do they need to protect?, VACCINE, Vol: 32, Pages: 3237-3242, ISSN: 0264-410X

Journal article

Drolet M, Laprise J-F, Boily M-C, Franco EL, Brisson Met al., 2014, Potential cost-effectiveness of the nonavalent human papillomavirus (HPV) vaccine, INTERNATIONAL JOURNAL OF CANCER, Vol: 134, Pages: 2264-2268, ISSN: 0020-7136

Journal article

Boily M-C, Shubber Z, 2014, Modelling in concentrated epidemics: informing epidemic trajectories and assessing prevention approaches, CURRENT OPINION IN HIV AND AIDS, Vol: 9, Pages: 134-149, ISSN: 1746-630X

Journal article

Boily M-C, Shubber Z, 2014, Modelling in concentrated epidemics: informing epidemic trajectories and assessing prevention approaches., Curr Opin HIV AIDS, Vol: 9, Pages: 134-149

PURPOSE OF THE REVIEW: This review summarizes recent mathematical modelling studies conducted among key populations including MSM, people who inject drugs (PWID), and female sex workers (FSWs) in low prevalence settings used as a marker of concentrated epidemics. RECENT FINDINGS: Most recent studies focused on MSM, Asian settings or high-income countries, studied the transmission dynamics or modelled pre-exposure prophylaxis, treatment as prevention or behavioural interventions specific to each key population (e.g., needle exchange programme or use of low-dead space syringes for PWID). Biological interventions were deemed effective and cost-effective, though still expensive, and often deemed unlikely to result in HIV elimination if used alone. Targeting high-risk individuals even within key populations improved efficiency. Some studies made innovative use of models to formally evaluate HIV prevention programmes, to interpret genetic or co-infection data, and to address methodological questions and validate epidemiological tools. CONCLUSION: More work is needed to optimize combination prevention focusing on key populations in different settings. The gaps identified include the limited number of studies modelling drug resistance, structural interventions, treatment as prevention among FSWs, and estimating the contribution of key populations to overall transmission in different settings.

Journal article

Mishra S, Pickles M, Blanchard JF, Moses S, Boily M-Cet al., 2014, Distinguishing sources of HIV transmission from the distribution of newly acquired HIV infections: why is it important for HIV prevention planning?, SEXUALLY TRANSMITTED INFECTIONS, Vol: 90, Pages: 19-25, ISSN: 1368-4973

Journal article

Eaton JW, Menzies NA, Stover J, Cambiano V, Chindelevitch L, Cori A, Hontelez JAC, Humair S, Kerr CC, Klein DJ, Mishra S, Mitchell KM, Nichols BE, Vickerman P, Bakker R, Baernighausen T, Bershteyn A, Bloom DE, Boily M-C, Chang ST, Cohen T, Dodd PJ, Fraser C, Gopalappa C, Lundgren J, Martin NK, Mikkelsen E, Mountain E, Pham QD, Pickles M, Phillips A, Platt L, Pretorius C, Prudden HJ, Salomon JA, van de Vijver DAMC, de Vlas SJ, Wagner BG, White RG, Wilson DP, Zhang L, Blandford J, Meyer-Rath G, Remme M, Revill P, Sangrujee N, Terris-Prestholt F, Doherty M, Shaffer N, Easterbrook PJ, Hirnschall G, Hallett TBet al., 2014, Health benefits, costs, and cost-effectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models, LANCET GLOBAL HEALTH, Vol: 2, Pages: E23-E34, ISSN: 2214-109X

Journal article

Mishra S, Mountain E, Pickles M, Vickerman P, Shastri S, Gilks C, Dhingra NK, Washington R, Becker ML, Blanchard JF, Alary M, Boily M-Cet al., 2014, Exploring the population-level impact of antiretroviral treatment: the influence of baseline intervention context, AIDS, Vol: 28, Pages: S61-S72, ISSN: 0269-9370

Journal article

Eaton JW, Menzies NA, Stover J, Cambiano V, Chindelevitch L, Cori A, Hontelez JAC, Humair S, Kerr CC, Klein DJ, Mishra S, Mitchell KM, Nichols BE, Vickerman P, Bakker R, Bärnighausen T, Bershteyn A, Bloom DE, Boily M-C, Chang ST, Cohen T, Dodd PJ, Fraser C, Gopalappa C, Lundgren J, Martin NK, Mikkelsen E, Mountain E, Pham QD, Pickles M, Phillips A, Platt L, Pretorius C, Prudden HJ, Salomon JA, van de Vijver DAMC, de Vlas SJ, Wagner BG, White RG, Wilson DP, Zhang L, Blandford J, Meyer-Rath G, Remme M, Revill P, Sangrujee N, Terris-Prestholt F, Doherty M, Shaffer N, Easterbrook PJ, Hirnschall G, Hallett TBet al., 2014, Health benefits, costs, and cost-effectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models., Lancet Glob Health, Vol: 2, Pages: e23-e34

BACKGROUND: New WHO guidelines recommend initiation of antiretroviral therapy for HIV-positive adults with CD4 counts of 500 cells per μL or less, a higher threshold than was previously recommended. Country decision makers have to decide whether to further expand eligibility for antiretroviral therapy accordingly. We aimed to assess the potential health benefits, costs, and cost-effectiveness of various eligibility criteria for adult antiretroviral therapy and expanded treatment coverage. METHODS: We used several independent mathematical models in four settings-South Africa (generalised epidemic, moderate antiretroviral therapy coverage), Zambia (generalised epidemic, high antiretroviral therapy coverage), India (concentrated epidemic, moderate antiretroviral therapy coverage), and Vietnam (concentrated epidemic, low antiretroviral therapy coverage)-to assess the potential health benefits, costs, and cost-effectiveness of various eligibility criteria for adult antiretroviral therapy under scenarios of existing and expanded treatment coverage, with results projected over 20 years. Analyses assessed the extension of eligibility to include individuals with CD4 counts of 500 cells per μL or less, or all HIV-positive adults, compared with the previous (2010) recommendation of initiation with CD4 counts of 350 cells per μL or less. We assessed costs from a health-system perspective, and calculated the incremental cost (in US$) per disability-adjusted life-year (DALY) averted to compare competing strategies. Strategies were regarded very cost effective if the cost per DALY averted was less than the country's 2012 per-head gross domestic product (GDP; South Africa: $8040; Zambia: $1425; India: $1489; Vietnam: $1407) and cost effective if the cost per DALY averted was less than three times the per-head GDP. FINDINGS: In South Africa, the cost per DALY averted of extending eligibility for antiretroviral therapy to adult patients with CD4 counts of 500 cells per μL

Journal article

Dimitrov D, Boily M-C, Brown ER, Hallett TBet al., 2013, Analytic Review of Modeling Studies of ARV Based PrEP Interventions Reveals Strong Influence of Drug-Resistance Assumptions on the Population-Level Effectiveness, PLOS One, Vol: 8, ISSN: 1932-6203

BackgroundFour clinical trials have shown that oral and topical pre-exposure prophylaxis (PrEP) based on tenofovir may be effective in preventing HIV transmission. The expected reduction in HIV transmission and the projected prevalence of drug resistance due to PrEP use vary significantly across modeling studies as a result of the broad spectrum of assumptions employed. Our goal is to quantify the influence of drug resistance assumptions on the predicted population-level impact of PrEP.MethodsAll modeling studies which evaluate the impact of oral or topical PrEP are reviewed and key assumptions regarding mechanisms of generation and spread of drug-resistant HIV are identified. A dynamic model of the HIV epidemic is developed to assess and compare the impact of oral PrEP using resistance assumptions extracted from published studies. The benefits and risks associated with ten years of PrEP use are evaluated under identical epidemic, behavioral and intervention conditions in terms of cumulative fractions of new HIV infections prevented, resistance prevalence among those infected with HIV, and fractions of infections in which resistance is transmitted.ResultsPublished models demonstrate enormous variability in resistance-generating assumptions and uncertainty in parameter values. Depending on which resistance parameterization is used, a resistance prevalence between 2% and 44% may be expected if 50% efficacious oral PrEP is used consistently by 50% of the population over ten years. We estimated that resistance may be responsible for up to a 10% reduction or up to a 30% contribution to the fraction of prevented infections predicted in different studies.ConclusionsResistance assumptions used in published studies have a strong influence on the projected impact of PrEP. Modelers and virologists should collaborate toward clarifying the set of resistance assumptions biologically relevant to the PrEP products which are already in use or soon to be added to the arsenal against

Journal article

Pickles M, Boily M-C, Vickerman P, Lowndes CM, Moses S, Blanchard JF, Deering KN, Bradley J, Ramesh BM, Washington R, Adhikary R, Mainkar M, Paranjape RS, Alary Met al., 2013, Assessment of the population-level effectiveness of the Avahan HIV-prevention programme in South India: a preplanned, causal-pathway-based modelling analysis, LANCET GLOBAL HEALTH, Vol: 1, Pages: E289-E299, ISSN: 2214-109X

Journal article

Behanzin L, Diabate S, Minani I, Lowndes CM, Boily M-C, Labbe A-C, Anagonou S, Zannou DM, Buve A, Alary Met al., 2013, Assessment of HIV-related risky behaviour: a comparative study of face-to-face interviews and polling booth surveys in the general population of Cotonou, Benin, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: 595-601, ISSN: 1368-4973

Journal article

Owen BN, Brock PM, Shubber Z, Baggaley RF, Butler AR, Pickles M, Brisson M, Drolet M, Boily MCet al., 2013, 31. Lifetime prevalence of anal intercourse among sexually active female youth and young female sex workers: a comparative systematic review and meta-analysis., ISSN: 1448-5028

Background Anal cancer incidence has increased over the past twenty years. Heterosexual anal intercourse (AI) is a risk factor for HPV and HIV infection but is under-researched and ill-understood. We compare AI practices among young, sexually active general population females and female sex workers (FSW). Methods: We searched PubMed for heterosexual AI studies among young females, including FSWs (mean age <25 years), to December 2012. Study estimates were pooled using a random-effects model. Results: Fifty-four studies (42 average-risk, 6 higher-risk, 6 FSWs) were included. Most studies among general population youth were conducted in North America using self-administered questionnaires. All FSW studies were conducted in Africa and Asia using face-to-face interviews (FTFI). Pooled estimates of lifetime AI prevalence were larger among average-risk (23.6%, 95% CI 20.4-26.7) and higher-risk youth (25.5%, 95% CI 11.7-39.2) than FSWs (12.8%, 95% CI 8.4-17.3), but highly heterogeneous (I2 >90%). However, pooled AI estimates by continent of average-risk youth (Asia=13.9%, 95% CI=1.7-29.5; Africa=18.4%, 95% CI 0.9-35.8) were more similar to those of FSWs (Asia=16.0%, 95% CI 10.3-21.6; Africa=9.7%, 95% CI 3.8-15.7). Estimates of average-risk youth reporting via FTFI (12.1%, 95% CI 0.7-23.5) were likewise similar to those among FSWs (12.8%, 95% CI 8.4-17.3). Pooled AI prevalence estimates among FSWs were higher in studies conducted after 2001 than in earlier studies. Conclusions: AI is common among sexually active females and may be increasing; it could therefore be an important determinant of HPV transmission and anal cancers. AI is as or more common among the general population youth than young FSWs but this may be confounded by continent, interview method and other unmeasured variables.

Conference paper

Dimitrov D, Boily M-C, Marrazzo J, Beigi R, Brown ERet al., 2013, Population-Level Benefits from Providing Effective HIV Prevention Means to Pregnant Women in High Prevalence Settings, PLOS One, Vol: 8, ISSN: 1932-6203

BackgroundHIV prevalence among pregnant women in Southern Africa is extremely high. Epidemiological studies suggest that pregnancy increases the risk of HIV sexual acquisition and that HIV infections acquired during pregnancy carry higher risk of mother-to-child transmission (MTCT). We analyze the potential benefits from extending the availability of effective microbicide to pregnant women (in addition to non-pregnant women) in a wide-scale intervention.Methods and FindingsA transmission dynamic model was designed to assess the impact of microbicide use in high HIV prevalence settings and to estimate proportions of new HIV infections, infections acquired during pregnancy, and MTCT prevented over 10 years. Our analysis suggests that consistent use of microbicide with 70% efficacy by 60% of non-pregnant women may prevent approximately 40% and 15% of new infections in women and men respectively over 10 years, assuming no additional increase in HIV risk to either partner during pregnancy (RRHIV/preg = 1). It may also prevent 8–15% MTCT depending on the increase in MTCT risk when HIV is acquired during pregnancy compared to before pregnancy (RRMTCT/preg). Extending the microbicides use during pregnancy may improve the effectiveness of the intervention by 10% (RRHIV/preg = 1) to 25% (RRHIV/preg = 2) and reduce the number of HIV infections acquired during pregnancy by 40% to 70% in different scenarios. It may add between 6% (RRHIV/preg = 1, RRMTCT/preg = 1) and 25% (RRHIV/preg = 2, RRMTCT/preg = 4) to the reduction in the residual MTCT.ConclusionProviding safe and effective microbicide to pregnant women in the context of wide-scale interventions would be desirable as it would increase the effectiveness of the intervention and significantly reduce the number of HIV infections acquired during pregnancy. The projected benefits from covering pregnant women by the HIV prevention programs is more substantial in communities in which the sexual risk during pregnancy is eleva

Journal article

Brisson M, Laprise J-F, Drolet M, Van de Velde N, Franco EL, Kliewer EV, Ogilvie G, Deeks SL, Boily M-Cet al., 2013, Comparative cost-effectiveness of the quadrivalent and bivalent human papillomavirus vaccines: A transmission-dynamic modeling study, VACCINE, Vol: 31, Pages: 3863-3871, ISSN: 0264-410X

Journal article

Dimitrov D, Boily MC, Mâsse BR, Brown ERet al., 2013, Impact of pill sharing on drug resistance due to a wide-scale oral prep intervention in generalized epidemics, Journal of AIDS and Clinical Research, Vol: 4

Background: The first antiretroviral drug (Truvada) to be used as a pre-exposure prophylaxis (PrEP) in preventing HIV transmission is about to be approved. Behavioral studies suggest that a portion of users may share anti-retroviral drugs with sex partners, family, or friends. Pill sharing will decrease PrEP efficacy and adherence level, and potentially create an environment favorable for the development of drug resistance. We aim to evaluate the potential impact of pill sharing on the PrEP effectiveness and on the rates of drug-resistance development in heterosexual populations. Methods: A transmission dynamic model was used to assess the population-level impact of oral PrEP. The fractions of new HIV infections prevented (CPF), drug resistance prevalence and the proportion of new infections in which drug-resistant HIV is transmitted (TDR) are evaluated over fixed time periods. The influence of different factors on CPF and TDR is studied through simulations, using epidemic parameters representative of the countries in Sub-Saharan Africa. Results: Without pill sharing, a 70% efficacious PrEP used consistently by 60% of uninfected individuals prevents 52.8% (95% CI 49.4%-56.4%) of all new HIV infections over ten years with drug-resistant HIV transmitted in 2.2% of the new infections. Absolute CPF may vary by 9% if up to 20% of the users share PrEP while the level of TDR and total resistance prevalence may increase by up to 6-fold due to pill sharing in some intervention scenarios. Conclusion: Pill sharing may increase the PrEP coverage level achieved in the population but it also affects the PrEP efficacy for the users who do not follow the prescribed schedule. More importantly, it creates a pool of untracked users who remain unreached by the effort to avoid sub-optimal PrEP usage by infected people. This increases substantially the potential risk of drug resistance in the population. © 2012 Dimitrov D, et al.

Journal article

Vesga JF, Boily MC, Hallett TB, 2013, ESTIMATING THE IMPACT OF ANTIRETROVIRAL THERAPY AND CONDOMS IN THE HIV EPIDEMIC OF BOGOTA, COLOMBIA, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A281-A281, ISSN: 1368-4973

Journal article

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: id=00396126&limit=30&person=true&page=3&respub-action=search.html