229 results found
Tavitian-Exley I, Boily MC, Vickerman P, 2013, HIV RISK IN PEOPLE WHO INJECT DIFFERENT DRUGS: SYSTEMATIC REVIEW AND META-ANALYSIS, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A179-A179, ISSN: 1368-4973
Shubber Z, Mishra S, Vesga JF, et al., 2013, THE HIV MODES OF TRANSMISSION MODEL: A SYSTEMATIC REVIEW OF ITS FINDINGS AND ADHERENCE TO GUIDELINES, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: A52-A52, ISSN: 1368-4973
Drolet M, Boily M-C, Van de Velde N, et al., 2013, Vaccinating Girls and Boys with Different Human Papillomavirus Vaccines: Can It Optimise Population-Level Effectiveness?, PLOS One, Vol: 8, ISSN: 1932-6203
BackgroundDecision-makers may consider vaccinating girls and boys with different HPV vaccines to benefit from their respective strengths; the quadrivalent (HPV4) prevents anogenital warts (AGW) whilst the bivalent (HPV2) may confer greater cross-protection. We compared, to a girls-only vaccination program with HPV4, the impact of vaccinating: 1) both genders with HPV4, and 2) boys with HPV4 and girls with HPV2.MethodsWe used an individual-based transmission-dynamic model of heterosexual HPV infection and diseases. Our base-case scenario assumed lifelong efficacy of 100% against vaccine types, and 46,29,8,18,6% and 77,43,79,8,0% efficacy against HPV-31,-33,-45,-52,-58 for HPV4 and HPV2, respectively.ResultsAssuming 70% vaccination coverage and lifelong cross-protection, vaccinating boys has little additional benefit on AGW prevention, irrespective of the vaccine used for girls. Furthermore, using HPV4 for boys and HPV2 for girls produces greater incremental reductions in SCC incidence than using HPV4 for both genders (12 vs 7 percentage points). At 50% vaccination coverage, vaccinating boys produces incremental reductions in AGW of 17 percentage points if both genders are vaccinated with HPV4, but increases female incidence by 16 percentage points if girls are switched to HPV2 (heterosexual male incidence is incrementally reduced by 24 percentage points in both scenarios). Higher incremental reductions in SCC incidence are predicted when vaccinating boys with HPV4 and girls with HPV2 versus vaccinating both genders with HPV4 (16 vs 12 percentage points). Results are sensitive to vaccination coverage and the relative duration of protection of the vaccines.ConclusionVaccinating girls with HPV2 and boys with HPV4 can optimize SCC prevention if HPV2 has higher/longer cross-protection, but can increase AGW incidence if vaccination coverage is low among boys.
Boily M-C, Pickles M, Lowndes CM, et al., 2013, Positive impact of a large-scale HIV prevention programme among female sex workers and clients in South India, AIDS, Vol: 27, Pages: 1449-1460, ISSN: 0269-9370
Boily M-C, Brisson M, Drolet M, et al., 2013, RE: Annual Report to the Nation on the Status of Cancer, 1975-2009, Featuring the Burden and Trends in Human Papillomavirus (HPV)-Associated Cancers and HPV Vaccination Coverage Levels and RE: Inequalities in Human Papillomavirus (HPV)-Associated Cancers: Implications for the Success of HPV Vaccination Response, JNCI-JOURNAL OF THE NATIONAL CANCER INSTITUTE, Vol: 105, Pages: 750-751, ISSN: 0027-8874
Behanzin L, Diabate S, Minani I, et al., 2013, Decline in the Prevalence of HIV and Sexually Transmitted Infections Among Female Sex Workers in Benin Over 15 Years of Targeted Interventions, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 63, Pages: 126-134, ISSN: 1525-4135
Phillips AE, Molitor J, Boily MC, et al., 2013, Informal confidential voting interviewing in a sexual risk assessment of men who have sex with men (MSM) and transgenders (hijra) in Bangalore, India, SEXUALLY TRANSMITTED INFECTIONS, Vol: 89, Pages: 245-250, ISSN: 1368-4973
Brisson M, Drolet M, Boily M-C, et al., 2013, RE: Population-Level Impact of the Bivalent, Quadrivalent, and Candidate Nonavalent Human Papillomavirus Vaccines: A Comparative Model-Based Analysis Response, JNCI-JOURNAL OF THE NATIONAL CANCER INSTITUTE, Vol: 105, Pages: 664-665, ISSN: 0027-8874
Drolet M, Boily M-C, Greenaway C, et al., 2013, Sociodemographic Inequalities in Sexual Activity and Cervical Cancer Screening: Implications for the Success of Human Papillomavirus Vaccination, CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION, Vol: 22, Pages: 641-652, ISSN: 1055-9965
Malagon T, Joumier V, Boily M-C, et al., 2013, The impact of differential uptake of HPV vaccine by sexual risks on health inequalities: A model-based analysis, VACCINE, Vol: 31, Pages: 1740-1747, ISSN: 0264-410X
Baggaley RF, Dimitrov D, Owen BN, et al., 2013, Heterosexual Anal Intercourse: A Neglected Risk Factor for HIV?, AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Vol: 69, Pages: 95-105, ISSN: 1046-7408
Deering KN, Bhattacharjee P, Mohan HL, et al., 2013, Violence and HIV Risk Among Female Sex Workers in Southern India, SEXUALLY TRANSMITTED DISEASES, Vol: 40, Pages: 168-174, ISSN: 0148-5717
Deering KN, Vickerman P, Pickles M, et al., 2013, Differences Between Seven Measures of Self-Reported Numbers of Clients of Female Sex Workers in Southern India: Implications for Individual- and Population-Level Analysis, AIDS AND BEHAVIOR, Vol: 17, Pages: 649-661, ISSN: 1090-7165
Bradley J, Rajaram S, Moses S, et al., 2013, Female Sex Worker Client Behaviors Lead to Condom Breakage: A Prospective Telephone-Based Survey in Bangalore, South India, AIDS AND BEHAVIOR, Vol: 17, Pages: 559-567, ISSN: 1090-7165
Dimitrov DT, Masse BR, Boily M-C, 2013, Beating the Placebo in HIV Prevention Efficacy Trials: The Role of the Minimal Efficacy Bound, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 62, Pages: 95-101, ISSN: 1525-4135
Baggaley RF, White RG, Hollingsworth TD, et al., 2013, Heterosexual HIV-1 Infectiousness and Antiretroviral Use: Systematic Review of Prospective Studies of Discordant Couples., Epidemiology, Vol: 1, Pages: 110-121
BACKGROUND: : Recent studies have estimated the reduction in HIV-1 infectiousness with antiretroviral therapy (ART), but high-quality studies such as randomized controlled trials, accompanied by rigorous adherence counseling, are likely to overestimate the effectiveness of treatment-as-prevention in real-life settings.METHODS: : We attempted to summarize the effect of ART on HIV transmission by undertaking a systematic review and meta-analysis of HIV-1 infectiousness per heterosexual partnership (incidence rate and cumulative incidence over study follow-up) estimated from prospective studies of discordant couples. We used random-effects Poisson regression models to obtain summary estimates. When possible, the analyses were further stratified by direction of transmission (man-to-woman or woman-to-man) and economic setting (high- or low-income countries). Potential causes of heterogeneity of estimates were explored through subgroup analyses.RESULTS: : Fifty publications were included. Nine allowed comparison between ART and non-ART users within studies (ART-stratified studies), in which summary incidence rates were 3.6/100 person-years (95% confidence interval = 2.0-6.5) and 0.2/100 person-years (0.07-0.7) for non-ART- and ART-using couples, respectively (P < 0.001), constituting a 91% (79-96%) reduction in per-partner HIV-1 incidence rate with ART use. The 41 studies that did not stratify by ART use provided estimates with high levels of heterogeneity (I statistic) and few reported levels of ART use, making interpretation difficult. Nevertheless, estimates tended to be lower with ART use. Infectiousness tended to be higher for low-income than high-income settings, but there was no clear pattern by direction of transmission (man-to-woman and woman-to-man).CONCLUSIONS: : ART substantially reduces HIV-1 infectiousness within discordant couples, based on observational studies, and could play a major part in HIV-1 prevention efforts. However, the non-zero risk from par
Owen BN, Brock PM, Baggaley RF, et al., 2012, Prevalence of heterosexual anal intercourse among youth: a systematic review and meta-analysis, 28th International Papillomavirus Conference
Mishra S, Steen R, Gerbase A, et al., 2012, Impact of High-Risk Sex and Focused Interventions in Heterosexual HIV Epidemics: A Systematic Review of Mathematical Models, PLOS One, Vol: 7, ISSN: 1932-6203
BackgroundThe core-group theory of sexually transmitted infections suggests that targeting prevention to high-risk groups (HRG) could be very effective. We aimed to quantify the contribution of heterosexual HRGs and the potential impact of focused interventions to HIV transmission in the wider community.MethodsWe systematically identified studies published between 1980 and 2011. Studies were included if they used dynamical models of heterosexual HIV transmission, incorporated behavioural heterogeneity in risk, and provided at least one of the following primary estimates in the wider community (a) the population attributable fraction (PAF) of HIV infections due to HRGs, or (b) the number per capita or fraction of HIV infections averted, or change in HIV prevalence/incidence due to focused interventions.FindingsOf 267 selected articles, 22 were included. Four studies measured the PAF, and 20 studies measured intervention impact across 265 scenarios. In low-prevalence epidemics (≤5% HIV prevalence), the estimated impact of sex-worker interventions in the absence of risk compensation included: 6–100% infections averted; 0.9–6.2 HIV infections averted per 100,000 adults; 11–94% and 4–47% relative reduction in prevalence and incidence respectively. In high-prevalence epidemics (>5% HIV prevalence), sex-worker interventions were estimated to avert 6.8–40% of HIV infections and up to 564 HIV infections per 100,000 adults, and reduce HIV prevalence and incidence by 13–27% and 2–14% respectively. In both types of epidemics, greater heterogeneity in HIV risk was associated with a larger impact on the fraction of HIV infections averted and relative reduction in HIV incidence.ConclusionFocused interventions, as estimated by mathematical models, have the potential to reduce HIV transmission in the wider community across low- and high-prevalence regions. However, considerable variability exists in estimated impact, suggesting that a
Van de Velde N, Boily M-C, Drolet M, et al., 2012, Population-Level Impact of the Bivalent, Quadrivalent, and Nonavalent Human Papillomavirus Vaccines: A Model-Based Analysis, JNCI-JOURNAL OF THE NATIONAL CANCER INSTITUTE, Vol: 104, Pages: 1712-1723, ISSN: 0027-8874
Malagon T, Drolet M, Boily M-C, et al., 2012, Cross-protective efficacy of two human papillomavirus vaccines: a systematic review and meta-analysis, LANCET INFECTIOUS DISEASES, Vol: 12, Pages: 781-789, ISSN: 1473-3099
Dimitrov D, Boily M-C, Marrazzo J, et al., 2012, Population-level benefits from providing effective HIV prevention means to pregnant women in high prevalence settings, JOURNAL OF THE INTERNATIONAL AIDS SOCIETY, Vol: 15, Pages: 79-79
Mitchell KM, Foss AM, Prudden HJ, et al., 2012, Sexual mixing patterns between men who have sex with men in southern India: implications for modelling the HIV epidemic and predicting the impact of targeted oral pre-exposure prophylaxis, Publisher: JOHN WILEY & SONS LTD, Pages: 106-107
Behanzin L, Diabate S, Minani I, et al., 2012, Decline in HIV Prevalence among Young Men in the General Population of Cotonou, Benin, 1998-2008, PLOS One, Vol: 7, ISSN: 1932-6203
ObjectiveTo assess changes in the prevalence of HIV and other sexually transmitted infections, as well as in different proximal and distal factors related to HIV infection, in the general population of Cotonou between 1998 and 2008, while an intensive preventive intervention targeting the sex work milieu was ongoing.MethodsA two-stage cluster sampling procedure was used to select the participants in each study. Subjects aged 15–49 who agreed to participate were interviewed and tested for HIV, syphilis, HSV-2, gonorrhoea and chlamydia. We used the Roa-Scott Chi-square test (proportions) and the Student’s t test (means) for bivariate comparisons, and adjusted logistic regression models taking into account the cluster effect for multivariate analyses.ResultsHIV prevalence decreased significantly in men (3.4% in 1998 versus 2.0% in 2008, p = 0.048), especially in those aged 15–29 (3.0% to 0.5%, p = 0.002). Among men, the prevalence of gonorrhoea decreased significantly (1.1% to 0.3%, p = 0.046) while HSV-2 prevalence increased from 12.0% to 18.1% (p = 0.0003). The proportion of men who reported condom use at least once (29.3% to 61.0%, p<0.0001) and of those having attained a secondary educational level or more (17.1% to 61.3%, p<0.0001) also increased significantly. There was an overall decrease in the prevalence of syphilis (1.5% to 0.6%, p = 0.0003).ConclusionThis is the first population-based study reporting a significant decline in HIV prevalence among young men in an African setting where overall prevalence has never reached 5%. The decline occurred while preventive interventions targeting the sex work milieu were ongoing and the educational level was increasing.
HIV Modelling Consortium Treatment as Prevention Editorial Writing Group, 2012, HIV treatment as prevention: models, data, and questions--towards evidence-based decision-making., PLOS Medicine, Vol: 9, ISSN: 1549-1277
Antiretroviral therapy (ART) for those infected with HIV can prevent onward transmission of infection, but biological efficacy alone is not enough to guide policy decisions about the role of ART in reducing HIV incidence. Epidemiology, economics, demography, statistics, biology, and mathematical modelling will be central in framing key decisions in the optimal use of ART. PLoS Medicine, with the HIV Modelling Consortium, has commissioned a set of articles that examine different aspects of HIV treatment as prevention with a forward-looking research agenda. Interlocking themes across these articles are discussed in this introduction. We hope that this article, and others in the collection, will provide a foundation upon which greater collaborations between disciplines will be formed, and will afford deeper insights into the key factors involved, to help strengthen the support for evidence-based decision-making in HIV prevention.
Boily M-C, Masse B, Alsallaq R, et al., 2012, HIV Treatment as Prevention: Considerations in the Design, Conduct, and Analysis of Cluster Randomized Controlled Trials of Combination HIV Prevention, PLOS Medicine, Vol: 9, ISSN: 1549-1277
Delva W, Eaton JW, Meng F, et al., 2012, HIV Treatment as Prevention: Optimising the Impact of Expanded HIV Treatment Programmes, PLOS Medicine, Vol: 9, ISSN: 1549-1277
Until now, decisions about how to allocate ART have largely been based on maximising the therapeutic benefit of ART for patients. Since the results of the HPTN 052 study showed efficacy of antiretroviral therapy (ART) in preventing HIV transmission, there has been increased interest in the benefits of ART not only as treatment, but also in prevention. Resources for expanding ART in the short term may be limited, so the question is how to generate the most prevention benefit from realistic potential increases in the availability of ART. Although not a formal systematic review, here we review different ways in which access to ART could be expanded by prioritising access to particular groups based on clinical or behavioural factors. For each group we consider (i) the clinical and epidemiological benefits, (ii) the potential feasibility, acceptability, and equity, and (iii) the affordability and cost-effectiveness of prioritising ART access for that group. In re-evaluating the allocation of ART in light of the new data about ART preventing transmission, the goal should be to create policies that maximise epidemiological and clinical benefit while still being feasible, affordable, acceptable, and equitable.
Dimitrov D, Boily M-C, Mâsse BR, et al., 2012, Impact of Pill Sharing on Drug Resistance Due to a Wide-Scale Oral Prep Intervention in Generalized Epidemics., J AIDS Clin Res, Vol: Suppl 5, ISSN: 2155-6113
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.
Boily MC, Brisson M, Mâsse B, et al., 2012, The role of mathematical models in vaccine development and public health decision making, Vaccinology: Principles and Practice, Pages: 480-508, ISBN: 9781405185745
Mohlala BKF, Gregson S, Boily M-C, 2012, Barriers to involvement of men in ANC and VCT in Khayelitsha, South Africa, Aids Care, Vol: 24, Pages: 972-977, ISSN: 1360-0451
We used qualitative methods to assess pregnant women and men's attitudes, feelings, beliefs, experiences and reactions to male partners' involvement in antenatal clinic (ANC) in Khayelitsha, Cape Town, South Africa. The aims of these studies were to determine barriers to male partners' attendance of ANC with their pregnant female partners and to identify possible strategies to overcome these barriers. Findings from the qualitative studies demonstrated that pregnant women were keen to invite their male sexual partners and that men would attend if invited. The main barrier to male participation was lack of awareness and the healthcare facility environment. The findings of these studies emphasized the need to increase awareness among men in Khayelitsha of the need for male attendance of ANC and the need to address the barriers to male attendance of ANC. It was clear that community sensitization programmes coupled with improvement of the health facility environment to be receptive to men are essential for increasing male attendance of ANC.
Bradley J, Rajaram SP, Moses S, et al., 2012, Why do condoms break? A study of female sex workers in Bangalore, south India, SEXUALLY TRANSMITTED INFECTIONS, Vol: 88, Pages: 163-170, ISSN: 1368-4973
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.