Imperial College London

ProfessorMarie-ClaudeBoily

Faculty of MedicineSchool of Public Health

Professor of Mathematical Epidemiology
 
 
 
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Contact

 

+44 (0)20 7594 3263mc.boily

 
 
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Location

 

LG26Norfolk PlaceSt Mary's Campus

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Summary

 

Publications

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249 results found

Mitchell KM, Maheu-Giroux M, Dimitrov D, Moore M, Hughes JP, Donnell D, Beyrer C, El-Sadr WM, Cohen MS, Boily MCet al., 2021, How can progress towards Ending the HIV Epidemic in the United States be monitored?, Clinical Infectious Diseases, ISSN: 1058-4838

Journal article

Elmes J, Stuart R, Grenfell P, Walker J, Hill K, Hernandez P, Henham C, Rutsito S, Sarker MD, Creighton S, Browne C, Boily M-C, Vickerman P, Platt Let al., 2021, Effect of police enforcement and extreme social inequalities on violence and mental health among women who sell sex: findings from a cohort study in London, UK., Sex Transm Infect

OBJECTIVES: To examine legal and social determinants of violence, anxiety/depression among sex workers. METHODS: A participatory prospective cohort study among women (inclusive of transgender) ≥18 years, selling sex in the last 3 months in London between 2018 and 2019. We used logistic generalised estimating equation models to measure associations between structural factors on recent (6 months) violence from clients or others (local residents, strangers), depression/anxiety (Patient Health Questionnaire-4). RESULTS: 197 sex workers were recruited (96% cisgender-women; 46% street-based; 54% off-street) and 60% completed a follow-up questionnaire. Street-based sex workers experienced greater inequalities compared with off-street in relation to recent violence from clients (73% vs 36%); police (42% vs 7%); intimate partner violence (IPV) (56% vs 18%) and others (67% vs 17%), as well as homelessness (65% vs 7%) and recent law enforcement (87% vs 9%). Prevalence of any STI was 17.5% (17/97). For street-based sex workers, recent arrest was associated with violence from others (adjusted OR (aOR) 2.77; 95% CI 1.11 to 6.94) and displacement by police was associated with client violence (aOR 4.35; 95% CI 1.36 to 13.90). Financial difficulties were also associated with client violence (aOR 4.66; 95% CI 1.64 to 13.24). Disability (aOR 3.85; 95% CI 1.49 to 9.95) and client violence (aOR 2.55; 95% CI 1.10 to 5.91) were associated with anxiety/depression. For off-street sex workers, financial difficulties (aOR 3.66; 95% CI 1.64 to 8.18), unstable residency (aOR 3.19; 95% CI 1.36 to 7.49), IPV (aOR 3.77; 95% CI 1.30 to 11.00) and alcohol/drug use were associated with client violence (aOR 3.16; 95% CI 1.26 to 7.92), while always screening and refusing clients was protective (aOR 0.36; 95% CI 0.15 to 0.87). Disability (aOR 5.83; 95% CI 2.34 to 14.51), unmet mental health needs (aOR 3.08; 95% CI 1.15 to 8.23) and past eviction (aOR 3.99; 95% CI 1.23 to 12.92) were associated with a

Journal article

Silhol R, Coupland H, Baggaley R, Miller L, Staadegaard L, Gottlieb S, Stannah J, Turner K, Vickerman P, Hayes R, Mayaud P, Looker K, Boily M-Cet al., 2021, What is the burden of heterosexually-acquired HIV due to HSV-2? Global and regional model-based estimates of the proportion and number of HIV infections attributable to HSV-2 infection, JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 88, Pages: 19-30, ISSN: 1525-4135

Background: Biological and epidemiological evidence suggest that herpes simplex virus type 2 (HSV-2) elevates HIV acquisition and transmission risk. We improved previous estimates of the contribution of HSV-2 to HIV infections by using a dynamic-transmission model.Setting: WHO regions.Methods: We developed a mathematical model of HSV-2/HIV transmission among 15-49-year-old heterosexual, non-drug-injecting populations, calibrated using region-specific demographic and HSV-2/HIV epidemiological data. We derived global and regional estimates of the contribution of HSV-2 to HIV infection over ten years (the transmission population-attributable fraction, tPAF) under three additive scenarios, assuming: (1) HSV-2 only increases HIV acquisition (“conservative”); (2) HSV-2 also increases HIV transmission (“liberal”); (3) HIV/ART (antiretroviral therapy) also modifies HSV-2 transmission and HSV-2 decreases ART effect on HIV transmission ("fully liberal”).Results: Under the conservative scenario, the predicted tPAF was 37.3% (95% uncertainty interval 33.4-43.2%) and an estimated 5.6 (4.5-7.0) million incident heterosexual HIV infections were due to HSV-2 globally over 2009-2018. The contribution of HSV-2 to HIV infections was largest for the African region (tPAF=42.6% (38.0-51.2%)), and lowest for the European region (tPAF=11.2% (7.9-13.8%)). The tPAF was higher among female sex-workers, their clients, and older populations, reflecting their higher HSV-2 prevalence. The tPAF was ∼50% and 1.3-2.4-fold higher for the liberal/fully liberal than the conservative scenario across regions.Conclusion: HSV-2 may have contributed to at least 37% of incident HIV infections in the last decade worldwide, and even more in Africa, and may continue to do so despite increased ART access unless future improved HSV-2 control measures, such as vaccines, become available.

Journal article

Drolet M, Laprise J-F, Martin D, Jit M, Bénard É, Gingras G, Boily M-C, Alary M, Baussano I, Hutubessy R, Brisson Met al., 2021, Optimal human papillomavirus vaccination strategies to prevent cervical cancer in low-income and middle-income countries in the context of limited resources: a mathematical modelling analysis, Lancet Infectious Diseases, ISSN: 1473-3099

BACKGROUND: Introduction of human papillomavirus (HPV) vaccination has been slow in low-income and middle-income countries (LMICs) because of resource constraints and worldwide shortage of vaccine supplies. To help inform WHO recommendations, we modelled various HPV vaccination strategies to examine the optimal use of limited vaccine supplies and best allocation of scarce resources in LMICs in the context of the WHO global call to eliminate cervical cancer as a public health problem. METHODS: In this mathematical modelling analysis, we developed HPV-ADVISE LMIC, a transmission-dynamic model of HPV infection and diseases calibrated to four LMICs: India, Vietnam, Uganda, and Nigeria. For different vaccination strategies that encompassed use of a nine-valent vaccine (or a two-valent or four-valent vaccine assuming high cross-protection), we estimated three outcomes: reduction in the age-standardised rate of cervical cancer, number of doses needed to prevent one case of cervical cancer (NNV; as a measure of efficiency), and the incremental cost-effectiveness ratio (ICER; in 2017 international $ per disability-adjusted life-year [DALY] averted). We examined different vaccination strategies by varying the ages of routine HPV vaccination and number of age cohorts vaccinated, the population targeted, and the number of doses used. In our base case, we assumed 100% lifetime protection against HPV-16, HPV-18, HPV-31, HPV-33, HPV-45, HPV-52, and HPV-58; vaccination coverage of 80%; and a time horizon of 100 years. For the cost-effectiveness analysis, we used a 3% discount rate. Elimination of cervical cancer was defined as an age-standardised incidence of less than four cases per 100 000 woman-years. FINDINGS: We predicted that HPV vaccination could lead to cervical cancer elimination in Vietnam, India, and Nigeria, but not in Uganda. Compared with no vaccination, strategies that involved vaccinating girls aged 9-14 years with two doses were predicted to be the most effi

Journal article

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

Mishra S, Silhol R, Knight J, PhaswanaMafuya R, Diouf D, Wang L, Schwartz S, Boily M, Baral Set al., 2021, Estimating the epidemic consequences of HIV prevention gaps among key populations, Journal of the International AIDS Society, Vol: 24, Pages: 1-6, ISSN: 1758-2652

IntroductionHIV epidemic appraisals are used to characterize heterogeneity and inequities in the context of the HIV pandemic and the response. However, classic measures used in appraisals have been shown to underestimate disproportionate risks of onward transmission, particularly among key populations. In response, a growing number of modelling studies have quantified the consequences of unmet prevention and treatment needs (prevention gaps) among key populations as a transmission population attributable fraction over time (tPAFt). To aid its interpretation and use by programme implementers and policy makers, we outline and discuss a conceptual framework for understanding and estimating the tPAFt via transmission modelling as a measure of onward transmission risk from HIV prevention gaps; and discuss properties of the tPAFt.DiscussionThe distribution of onward transmission risks may be defined by who is at disproportionate risk of onward transmission, and under which conditions. The latter reflects prevention gaps, including secondary prevention via treatment: the epidemic consequences of which may be quantified by the tPAFt. Steps to estimating the tPAFt include parameterizing the acquisition and onward transmission risks experienced by the subgroup of interest, defining the most relevant counterfactual scenario, and articulating the time-horizon of analyses and population among whom to estimate the relative difference in cumulative transmissions; such steps could reflect programme-relevant questions about onward transmission risks. Key properties of the tPAFt include larger onward transmission risks over longer time-horizons; seemingly mutually exclusive tPAFt measures summing to greater than 100%; an opportunity to quantify the magnitude of disproportionate onward transmission risks with a per-capita tPAFt; and that estimates are conditional on what has been achieved so far in reducing prevention gaps and maintaining those conditions moving forward as the status

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

d'Elbée M, Traore MM, Badiane K, Vautier A, Simo Fotso A, Kabemba OK, Rouveau N, Godfrey-Faussett P, Maheu-Giroux M, Boily M-C, Medley GF, Larmarange J, Terris-Prestholt Fet al., 2021, Costs and scale-up costs of integrating HIV self-testing into civil society organisation-led programmes for key populations in Côte d'Ivoire, Senegal, and Mali, Frontiers in Public Health, Vol: 9, ISSN: 2296-2565

Despite significant progress on the proportion of individuals who know their HIV status in 2020, Côte d'Ivoire (76%), Senegal (78%), and Mali (48%) remain far below, and key populations (KP) including female sex workers (FSW), men who have sex with men (MSM), and people who use drugs (PWUD) are the most vulnerable groups with a HIV prevalence at 5-30%. HIV self-testing (HIVST), a process where a person collects his/her own specimen, performs a test, and interprets the result, was introduced in 2019 as a new testing modality through the ATLAS project coordinated by the international partner organisation Solthis (IPO). We estimate the costs of implementing HIVST through 23 civil society organisations (CSO)-led models for KP in Côte d'Ivoire (N = 7), Senegal (N = 11), and Mali (N = 5). We modelled costs for programme transition (2021) and early scale-up (2022-2023). Between July 2019 and September 2020, a total of 51,028, 14,472, and 34,353 HIVST kits were distributed in Côte d'Ivoire, Senegal, and Mali, respectively. Across countries, 64-80% of HIVST kits were distributed to FSW, 20-31% to MSM, and 5-8% to PWUD. Average costs per HIVST kit distributed were $15 for FSW (Côte d'Ivoire: $13, Senegal: $17, Mali: $16), $23 for MSM (Côte d'Ivoire: $15, Senegal: $27, Mali: $28), and $80 for PWUD (Côte d'Ivoire: $16, Senegal: $144), driven by personnel costs (47-78% of total costs), and HIVST kits costs (2-20%). Average costs at scale-up were $11 for FSW (Côte d'Ivoire: $9, Senegal: $13, Mali: $10), $16 for MSM (Côte d'Ivoire: $9, Senegal: $23, Mali: $17), and $32 for PWUD (Côte d'Ivoire: $14, Senegal: $50). Cost reductions were mainly explained by the spreading of IPO costs over higher HIVST distribution volumes and progressive IPO withdrawal at scale-up. In all countries, CSO-led HIVST kit provision to KP showed relatively high costs during the study period related to the progressive integration of the programme to CSO a

Journal article

Silhol R, Baral S, Bowring A, Mukandavire C, Mfochive Njindam I, Rao A, Schwartz S, Tamoufe U, Billong S, Njoya O, Zoung-Kanyi Bissek A-C, Garcia Calleja JM, Vickerman P, Mishra S, Boily M-Cet al., 2021, Quantifying the evolving contribution of HIV interventions and key populations to the HIV epidemic in Yaoundé, Cameroon, JAIDS: Journal of Acquired Immune Deficiency Syndromes, Vol: 86, Pages: 396-405, ISSN: 1525-4135

Background: Key populations (KP) including men who have sex with men (MSM), female sex workers (FSW), and their clients are disproportionately affected by HIV in Sub-Saharan Africa. We estimated the evolving impact of past interventions and contribution of unmet HIV prevention/treatment needs of KP and lower-risk groups to HIV transmission.Setting: Yaoundé, Cameroon.Methods: We parametrised and fitted a deterministic of HIV transmission model to Yaoundé-specific demographic, behavioural, HIV and intervention coverage data in a Bayesian framework. We estimated the fraction of incident HIV infections averted by condoms and antiretroviral therapy (ART) and the fraction of all infections over 10-year periods directly and indirectly attributable to unprotected sex within and between each risk group.Results: Condom use and ART together may have averted 43% (95% uncertainty interval: 31-54) of incident infections over 1980-2018 and 72% (66-79) over 2009-2018. Most onward transmissions over 2009-2018 stemmed from unprotected sex between lower-risk individuals (47% (32-61)), clients (37% (23-51)), and MSM (35% (20-54)) with all their partners. The contribution of commercial sex decreased from 25% (8-49) over 1989-1998 to 8% (3-22) over 2009-2018, due to higher intervention coverage among FSW.Conclusion: Condom use and recent ART scale-up mitigated the HIV epidemic in Yaoundé and changed the contribution of different partnerships to onward transmission over time. Findings highlight the importance of prioritizing HIV prevention and treatment for MSM and clients of FSW whose unmet needs now contribute most to onward transmission, while maintaining services which successfully reduced transmissions in the context of commercial sex.

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

Xia Y, Milwid RM, Godin A, Boily M-C, Johnson LF, Marsh K, Eaton J, Maheu-Giroux Met al., 2021, Accuracy of self-reported HIV testing history and awareness of HIV-positive status among people living with HIV in four Sub-Saharan African countries, AIDS, Vol: 35, Pages: 503-510, ISSN: 0269-9370

Background: In many countries in Sub-Saharan Africa, self-reported HIV testing history and awareness of HIV-positive status from household surveys are used to estimate the percentage of people living with HIV (PLHIV) who know their HIV status. Despite widespread use, there is limited empirical information on the sensitivity of those self-reports, which can be affected by non-disclosure.Methods: Bayesian latent class models were used to estimate the sensitivity of self-reported HIV testing history and awareness of HIV-positive status in four Population-based HIV Impact Assessment surveys in Eswatini, Malawi, Tanzania, and Zambia. Antiretroviral (ARV) metabolites biomarkers were used to identify persons on treatment who did not accurately report their status. For those without ARV biomarkers, the pooled estimate of non-disclosure among untreated persons was 1.48 higher than those on treatment.Results: Among PLHIV, the model-estimated sensitivity of self-reported HIV testing history ranged from 96% to 99% across surveys. The model-estimated sensitivity of self-reported awareness of HIV status varied from 91% to 97%. Non-disclosure was generally higher among men and those aged 15–24 years. Adjustments for imperfect sensitivity did not substantially influence estimates of PLHIV ever tested (difference <4%) but the proportion of PLHIV aware of their HIV-positive status was higher than the unadjusted proportion (difference <8%).Conclusions: Self-reported HIV testing histories in four Eastern and Southern African countries are generally robust although adjustment for non-disclosure increases estimated awareness of status. These findings can contribute to further refinements in methods for monitoring progress along the HIV testing and treatment cascade.

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

Rouveau N, Ky-Zerbo O, Boye S, Fotso AS, d'Elbée M, Maheu-Giroux M, Silhol R, Kouassi AK, Vautier A, Doumenc-Aïdara C, Breton G, Keita A, Ehui E, Ndour CT, Boilly M-C, Terris-Prestholt F, Pourette D, Desclaux A, Larmarange J, ATLAS Teamet al., 2021, Describing, analysing and understanding the effects of the introduction of HIV self-testing in West Africa through the ATLAS programme in Côte d'Ivoire, Mali and Senegal., BMC Public Health, Vol: 21, Pages: 1-14, ISSN: 1471-2458

BACKGROUND: The ATLAS programme aims to promote and implement HIV self-testing (HIVST) in three West African countries: Côte d'Ivoire, Mali, and Senegal. During 2019-2021, in close collaboration with the national AIDS implementing partners and communities, ATLAS plans to distribute 500,000 HIVST kits through eight delivery channels, combining facility-based, community-based strategies, primary and secondary distribution of HIVST. Considering the characteristics of West African HIV epidemics, the targets of the ATLAS programme are hard-to-reach populations: key populations (female sex workers, men who have sex with men, and drug users), their clients or sexual partners, partners of people living with HIV and patients diagnosed with sexually transmitted infections and their partners. The ATLAS programme includes research support implementation to generate evidence for HIVST scale-up in West Africa. The main objective is to describe, analyse and understand the social, health, epidemiological effects and cost-effectiveness of HIVST introduction in Côte d'Ivoire, Mali and Senegal to improve the overall HIV testing strategy (accessibility, efficacy, ethics). METHODS: ATLAS research is organised into five multidisciplinary workpackages (WPs): Key Populations WP: qualitative surveys (individual in-depth interviews, focus group discussions) conducted with key actors, key populations, and HIVST users. Index testing WP: ethnographic observation of three HIV care services introducing HIVST for partner testing. Coupons survey WP: an anonymous telephone survey of HIVST users. Cost study WP: incremental economic cost analysis of each delivery model using a top-down costing with programmatic data, complemented by a bottom-up costing of a representative sample of HIVST distribution sites, and a time-motion study for health professionals providing HIVST. Modelling WP: Adaptation, parameterisation and calibration of a dynamic compartmental model that considers the varied p

Journal article

Stone J, Mukandavire C, Boily M-C, Fraser H, Mishra S, Schwartz S, Rao A, Looker KJ, Quaife M, Terris-Prestholt F, Marr A, Lane T, Coetzee J, Gray G, Otwombe K, Milovanovic M, Hausler H, Young K, Mcingana M, Ncedani M, Puren A, Hunt G, Kose Z, Phaswana-Mafuya N, Baral S, Vickerman Pet al., 2021, Estimating the contribution of key populations towards HIV transmission in South Africa, Journal of the International AIDS Society, Vol: 24, ISSN: 1758-2652

INTRODUCTION: In generalized epidemic settings, there is insufficient understanding of how the unmet HIV prevention and treatment needs of key populations (KPs), such as female sex workers (FSWs) and men who have sex with men (MSM), contribute to HIV transmission. In such settings, it is typically assumed that HIV transmission is driven by the general population. We estimated the contribution of commercial sex, sex between men, and other heterosexual partnerships to HIV transmission in South Africa (SA). METHODS: We developed the "Key-Pop Model"; a dynamic transmission model of HIV among FSWs, their clients, MSM, and the broader population in SA. The model was parameterized and calibrated using demographic, behavioural and epidemiological data from national household surveys and KP surveys. We estimated the contribution of commercial sex, sex between men and sex among heterosexual partnerships of different sub-groups to HIV transmission over 2010 to 2019. We also estimated the efficiency (HIV infections averted per person-year of intervention) and prevented fraction (% IA) over 10-years from scaling-up ART (to 81% coverage) in different sub-populations from 2020. RESULTS: Sex between FSWs and their paying clients, and between clients with their non-paying partners contributed 6.9% (95% credibility interval 4.5% to 9.3%) and 41.9% (35.1% to 53.2%) of new HIV infections in SA over 2010 to 2019 respectively. Sex between low-risk groups contributed 59.7% (47.6% to 68.5%), sex between men contributed 5.3% (2.3% to 14.1%) and sex between MSM and their female partners contributed 3.7% (1.6% to 9.8%). Going forward, the largest population-level impact on HIV transmission can be achieved from scaling up ART to clients of FSWs (% IA = 18.2% (14.0% to 24.4%) or low-risk individuals (% IA = 20.6% (14.7 to 27.5) over 2020 to 2030), with ART scale-up among KPs being most efficient. CONCLUSIONS: Clients of FSWs play a fundamental role in HIV transmiss

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

Wang L, Ma H, Yiu KCY, Calzavara A, Landsman D, Luong L, Chan AK, Kustra R, Kwong JC, Boily M-C, Hwang S, Straus S, Baral SD, Mishra Set al., 2020, Heterogeneity in testing, diagnosis and outcome in SARS-CoV-2 infection across outbreak settings in the Greater Toronto Area, Canada: an observational study., CMAJ Open, Vol: 8, Pages: E627-E636, ISSN: 2291-0026

BACKGROUND: Congregate settings have been disproportionately affected by coronavirus disease 2019 (COVID-19). Our objective was to compare testing for, diagnosis of and death after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection across 3 settings (residents of long-term care homes, people living in shelters and the rest of the population). METHODS: We conducted a population-based prospective cohort study involving individuals tested for SARS-CoV-2 in the Greater Toronto Area between Jan. 23, 2020, and May 20, 2020. We sourced person-level data from COVID-19 surveillance and reporting systems in Ontario. We calculated cumulatively diagnosed cases per capita, proportion tested, proportion tested positive and case-fatality proportion for each setting. We estimated the age- and sex-adjusted rate ratios associated with setting for test positivity and case fatality using quasi-Poisson regression. RESULTS: Over the study period, a total of 173 092 individuals were tested for and 16 490 individuals were diagnosed with SARS-CoV-2 infection. We observed a shift in the proportion of cumulative cases from all cases being related to travel to cases in residents of long-term care homes (20.4% [3368/16 490]), shelters (2.3% [372/16 490]), other congregate settings (20.9% [3446/16 490]) and community settings (35.4% [5834/16 490]), with cumulative travel-related cases at 4.1% (674/16490). Cumulatively, compared with the rest of the population, the diagnosed cases per capita was 64-fold and 19-fold higher among long-term care home and shelter residents, respectively. By May 20, 2020, 76.3% (21 617/28 316) of long-term care home residents and 2.2% (150 077/6 808 890) of the rest of the population had been tested. After adjusting for age and sex, residents of long-term care homes were 2.4 (95% confidence interval [CI] 2.2-2.7) times more likely to test positive, and those who received a diagnosis of COVID-19 were 1.4-fold (95% CI 1.1-1.8) more likely to die than

Journal article

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

Xia Y, Milwid R, Godin A, Boily M-C, Johnson L, Marsh K, Eaton J, Maheu-Giroux Met al., 2020, Accuracy of self-reported HIV testing history and awareness of HIV-positive status among people living with HIV in four Sub-Saharan African countries

Background: In many countries in Sub-Saharan Africa, self-reported HIV testing history and awareness of HIV-positive status from household surveys are used to estimate the percentage of people living with HIV (PLHIV) who know their HIV status. Despite widespread use, there is limited empirical information on the sensitivity of those self-reports, which can be affected by non-disclosure. Methods: Bayesian latent class models were used to estimate the sensitivity of self-reported HIV testing history and awareness of HIV-positive status in four Population-based HIV Impact Assessment surveys in Eswatini, Malawi, Tanzania, and Zambia. Antiretroviral (ARV) metabolites biomarkers were used to identify persons on treatment who did not accurately report their status. For those without ARV biomarkers, the pooled estimate of non-disclosure among untreated persons was 1.48 higher than those on treatment. Results: Among PLHIV, the sensitivity of self-reported HIV testing history ranged 96% to 99% across surveys. Sensitivity of self-reported awareness of HIV status varied from 91% to 97%. Non-disclosure was generally higher among men and those aged 15-24 years. Adjustments for imperfect sensitivity did not substantially influence estimates of of PLHIV ever tested (difference <4%) but the proportion of PLHIV aware of their HIV-positive status was higher than the unadjusted proportion (difference <8%). Conclusions: Self-reported HIV testing histories in four Eastern and Southern African countries are generally robust although adjustment for non-disclosure increases estimated awareness of status. These findings can contribute to further refinements in methods for monitoring progress along the HIV testing and treatment cascade.

Working paper

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

Owen BN, Baggaley R, Maheu-Giroux M, Elmes J, Adimora A, Ramirez C, Edmonds A, Sosanya K, Taylor T, Plankey M, Cederbaum J, Seidman D, Weber K, Golub E, Sheth A, Bolivar H, Konkle-PArker D, Boily M-Cet al., 2020, Patterns and trajectories of anal intercourse practice over the life course among US women at risk of HIV, JIAS (submitted)

Journal article

Elmes J, Silhol R, Hess KL, Gedge LM, Nordsletten A, Staunton R, Anton P, Shacklett B, McGowan I, Dang Q, Adimora AA, Dimitrov DT, Aral S, Handanagic S, PazBailey G, Boily Met al., 2020, Receptive anal sex contributes substantially to heterosexually‐acquired HIV infections among at‐risk women in Twenty US Cities: results from a modelling analysis, American Journal of Reproductive Immunology, Vol: 84, Pages: 1-14, ISSN: 1046-7408

ProblemReceptive anal intercourse (RAI) is more efficient than receptive vaginal intercourse (RVI) at transmitting HIV, but its contribution to heterosexually‐acquired HIV infections among at‐risk women in the US is unclear.Method of studyWe analysed sexual behaviour data from surveys of 9,152 low‐income heterosexual women living in 20 cities with high rates of HIV conducted in 2010 and 2013 as part of US National HIV Behavioral Surveillance. We estimated RAI prevalence (past‐year RAI) and RAI fraction (fraction of all sex acts (RVI and RAI) at the last sexual episode that were RAI among those reporting past‐year RAI) overall and by key demographic characteristics. These results and HIV incidence were used to calibrate a risk‐equation model to estimate the population attributable fraction of new HIV infections due to RAI (PAFRAI) accounting for uncertainty in parameter assumptions.ResultsRAI prevalence (overall: 32%, city range: 19‐60%) and RAI fraction (overall: 27%, city‐range: 18‐34%) were high overall and across cities, and positively associated with exchange sex. RAI accounted for an estimated 41% (uncertainty range: 18‐55%) of new infections overall (city range: 21‐57%). Variability in PAFRAI estimates was most influenced by uncertainty in the estimate of the per‐act increased risk of RAI relative to RVI and the number of sex acts.ConclusionsRAI may contribute disproportionately to new heterosexually‐acquired HIV infections among at‐risk low‐income women in the US, meaning that tools to prevent HIV transmission during RAI are warranted. Number of RVI and RAI acts should also be collected to monitor heterosexually‐acquired HIV infections.

Journal article

Owen BN, Maheu-Giroux M, Matse S, Mnisi Z, Baral S, Ketende SC, Baggaley RF, Boily M-Cet al., 2020, Prevalence and correlates of anal intercourse among female sex workers in eSwatini (vol 15, e0228849, 2020), PLOS ONE, Vol: 15, ISSN: 1932-6203

Journal article

Owen BN, Baggaley RF, Elmes J, Harvey A, Shubber Z, Butler AR, Silhol R, Anton P, Shacklett B, van der Straten A, Boily MCet al., 2020, What proportion of female sex workers practise anal intercourse and how frequently? A systematic review and meta-analysis, AIDS and Behavior, Vol: 24, Pages: 697-713, ISSN: 1090-7165

HIV is more efficiently acquired during receptive anal intercourse (AI) compared to vaginal intercourse (VI) and may contribute substantially to female sex workers’ (FSW) high HIV burden. We aim to determine how common and frequent AI is among FSW globally. We searched PubMed, Embase and PsycINFO for studies reporting the proportion of FSW practising AI (prevalence) and/or the number of AI acts (frequency) worldwide from 01/1980 to 10/2018. We assessed the influence of participant and study characteristics on AI prevalence (e.g. continent, study year and interview method) through sub-group analysis. Of 15,830 identified studies, 131 were included. Nearly all (N = 128) reported AI prevalence and few frequency (N = 13), over various recall periods. Most studies used face-to-face interviews (N = 111). Pooled prevalences varied little by recall period (lifetime: 15.7% 95%CI 12.2–19.3%, N = 30, I 2 = 99%; past month: 16.2% 95%CI 10.8–21.6%, N = 18, I 2 = 99%). The pooled proportion of FSW reporting < 100% condom use tended to be non-significantly higher during AI compared to during VI (e.g. any unprotected VI: 19.1% 95%CI 1.7–36.4, N = 5 and any unprotected AI: 46.4% 95%CI 9.1–83.6, N = 5 in the past week). Across all study participants, between 2.4 and 15.9% (N = 6) of all intercourse acts (AI and VI) were anal. Neither AI prevalence nor frequency varied substantially by any participant or study characteristics. Although varied, AI among FSW is generally common, inconsistently protected with condoms and practiced sufficiently frequently to contribute substantially to HIV acquisition in this risk group. Interventions to address barriers to condom use are needed.

Journal article

Nascimento FF, Baral S, Geidelberg L, Mukandavire C, Schwartz SR, Turpin G, Turpin N, Diouf D, Diouf NL, Coly K, Kane CT, Ndour C, Vickerman P, Boily M-C, Volz EMet al., 2020, Phylodynamic analysis of HIV-1 subtypes B, C and CRF 02_AG in Senegal, Epidemics: the journal of infectious disease dynamics, Vol: 30, Pages: 1-11, ISSN: 1755-4365

Surveillance of HIV epidemics in key populations and in developing countries is often challenging due to sparse, incomplete, or low-quality data. Analysis of HIV sequence data can provide an alternative source of information about epidemic history, population structure, and transmission patterns. To understand HIV-1 dynamics and transmission patterns in Senegal, we carried out model-based phylodynamic analyses using the structured-coalescent approach using HIV-1 sequence data from three different subgroups: reproductive aged males and females from the adult Senegalese population and men who have sex with other men (MSM). We fitted these phylodynamic analyses to time-scaled phylogenetic trees individually for subtypes C and CRF 02_AG, and for the combined data for subtypes B, C and CRF 02_AG. In general, the combined analysis showed a decreasing proportion of effective number of infections among all reproductive aged adults relative to MSM. However, we observed a nearly time-invariant distribution for subtype CRF 02_AG and an increasing trend for subtype C on the proportion of effective number of infections. The population attributable fraction also differed between analyses: subtype CRF 02_AG showed little contribution from MSM, while for subtype C and combined analyses this contribution was much higher. Despite observed differences, results suggested that the combination of high assortativity among MSM and the unmet HIV prevention and treatment needs represent a significant component of the HIV epidemic in Senegal.

Journal article

Looker KJ, Johnston C, Welton NJ, James C, Vickerman P, Turner KME, Boily M-C, Gottlieb SLet al., 2020, The global and regional burden of genital ulcer disease due to herpes simplex virus: a natural history modelling study, BMJ Global Health, Vol: 5, Pages: 1-15, ISSN: 2059-7908

Introduction Herpes simplex virus (HSV) infection can cause painful, recurrent genital ulcer disease (GUD), which can have a substantial impact on sexual and reproductive health. HSV-related GUD is most often due to HSV type 2 (HSV-2), but may also be due to genital HSV type 1 (HSV-1), which has less frequent recurrent episodes than HSV-2. The global burden of GUD has never been quantified. Here we present the first global and regional estimates of GUD due to HSV-1 and HSV-2 among women and men aged 15–49 years old.Methods We developed a natural history model reflecting the clinical course of GUD following HSV-2 and genital HSV-1 infection, informed by a literature search for data on model parameters. We considered both diagnosed and undiagnosed symptomatic infection. This model was then applied to existing infection estimates and population sizes for 2016. A sensitivity analysis was carried out varying the assumptions made.Results We estimated that 187 million people aged 15–49 years had at least one episode of HSV-related GUD globally in 2016: 5.0% of the world’s population. Of these, 178 million (95% of those with HSV-related GUD) had HSV-2 compared with 9 million (5%) with HSV-1. GUD burden was highest in Africa, and approximately double in women compared with men. Altogether there were an estimated 8 billion person-days spent with HSV-related GUD globally in 2016, with 99% of days due to HSV-2. Taking into account parameter uncertainty, the percentage with at least one episode of HSV-related GUD ranged from 3.2% to 7.9% (120–296 million). However, the estimates were sensitive to the model assumptions.Conclusion Our study represents a first attempt to quantify the global burden of HSV-related GUD, which is large. New interventions such as HSV vaccines, antivirals or microbicides have the potential to improve the quality of life of millions of people worldwide.

Journal article

Brisson M, Kim JJ, Canfell K, Drolet M, Gingras G, Burger EA, Martin D, Simms KT, Benard E, Boily M-C, Sy S, Regan C, Keane A, Caruana M, Nguyen DTN, Smith MA, Laprise J-F, Jit M, Alary M, Bray F, Fidarova E, Elsheikh F, Bloem PJN, Broutet N, Hutubessy Ret al., 2020, Impact of HPV vaccination and cervical screening on cervical cancer elimination: a comparative modelling analysis in 78 low-income and lower-middle-income countries, The Lancet, Vol: 395, Pages: 575-590, ISSN: 0140-6736

BackgroundThe WHO Director-General has issued a call for action to eliminate cervical cancer as a public health problem. To help inform global efforts, we modelled potential human papillomavirus (HPV) vaccination and cervical screening scenarios in low-income and lower-middle-income countries (LMICs) to examine the feasibility and timing of elimination at different thresholds, and to estimate the number of cervical cancer cases averted on the path to elimination.MethodsThe WHO Cervical Cancer Elimination Modelling Consortium (CCEMC), which consists of three independent transmission-dynamic models identified by WHO according to predefined criteria, projected reductions in cervical cancer incidence over time in 78 LMICs for three standardised base-case scenarios: girls-only vaccination; girls-only vaccination and once-lifetime screening; and girls-only vaccination and twice-lifetime screening. Girls were vaccinated at age 9 years (with a catch-up to age 14 years), assuming 90% coverage and 100% lifetime protection against HPV types 16, 18, 31, 33, 45, 52, and 58. Cervical screening involved HPV testing once or twice per lifetime at ages 35 years and 45 years, with uptake increasing from 45% (2023) to 90% (2045 onwards). The elimination thresholds examined were an average age-standardised cervical cancer incidence of four or fewer cases per 100 000 women-years and ten or fewer cases per 100 000 women-years, and an 85% or greater reduction in incidence. Sensitivity analyses were done, varying vaccination and screening strategies and assumptions. We summarised results using the median (range) of model predictions.FindingsGirls-only HPV vaccination was predicted to reduce the median age-standardised cervical cancer incidence in LMICs from 19·8 (range 19·4–19·8) to 2·1 (2·0–2·6) cases per 100 000 women-years over the next century (89·4% [86·2–90·1] reduction), and to avert 61·0 million

Journal article

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