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Many countries affected by the global outbreak of mpox in 2022 have observed a decline in cases. Our mathematical model accounting for heavy-tailed sexual partnership distributions suggests that mpox epidemics can hit the infection-derived herd immunity threshold and begin to decline, with <1% of sexually active men who have sex with men infected regardless of interventions or behavioral changes. We consistently found that many countries and US states experienced an epidemic peak, with cumulative cases of around 0.1% to 0.5% among men who have sex with men. The observed decline in cases may not necessarily be attributable to interventions or behavioral changes primarily.
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Mpox , Minorias Sexuais e de Gênero , Masculino , Humanos , Homossexualidade Masculina , Comportamento Sexual , Surtos de DoençasRESUMO
We conducted a systematic literature review of general population testing, contact tracing, case isolation and contact quarantine interventions to assess their effectiveness in reducing SARS-CoV-2 transmission, as implemented in real-world settings. We designed a broad search strategy and aimed to identify peer-reviewed studies of any design provided there was a quantitative measure of effectiveness on a transmission outcome. Studies that assessed the effect of testing or diagnosis on disease outcomes via treatment, but did not assess a transmission outcome, were not included. We focused on interventions implemented among the general population rather than in specific settings; these were from anywhere in the world and published any time after 1 January 2020 until the end of 2022. From 26 720 titles and abstracts, 1181 were reviewed as full text, and 25 met our inclusion criteria. These 25 studies included one randomized control trial (RCT) and the remaining 24 analysed empirical data and made some attempt to control for confounding. Studies included were categorized by the type of intervention: contact tracing (seven studies); specific testing strategies (12 studies); strategies for isolating cases/contacts (four studies); and 'test, trace, isolate' (TTI) as a part of a package of interventions (two studies). None of the 25 studies were rated at low risk of bias and many were rated as serious risk of bias, particularly due to the likely presence of uncontrolled confounding factors, which was a major challenge in assessing the independent effects of TTI in observational studies. These confounding factors are to be expected from observational studies during an on-going pandemic, when the emphasis was on reducing the epidemic burden rather than trial design. Findings from these 25 studies suggested an important public health role for testing followed by isolation, especially where mass and serial testing was used to reduce transmission. Some of the most compelling analyses came from examining fine-grained within-country data on contact tracing; while broader studies which compared behaviour between countries also often found TTI led to reduced transmission and mortality, this was not universal. There was limited evidence for the benefit of isolation of cases/contacts away from the home environment. One study, an RCT, showed that daily testing of contacts could be a viable strategy to replace lengthy quarantine of contacts. Based on the scarcity of robust empirical evidence, we were not able to draw any firm quantitative conclusions about the quantitative impact of TTI interventions in different epidemic contexts. While the majority of studies found that testing, tracing and isolation reduced transmission, evidence for the scale of this impact is only available for specific scenarios and hence is not necessarily generalizable. Our review therefore emphasizes the need to conduct robust experimental studies that help inform the likely quantitative impact of different TTI interventions on transmission and their optimal design. Work is needed to support such studies in the context of future emerging epidemics, along with assessments of the cost-effectiveness of TTI interventions, which was beyond the scope of this review but will be critical to decision-making. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'.
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COVID-19 , SARS-CoV-2 , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , Busca de Comunicante , Saúde Pública , Pandemias/prevenção & controleRESUMO
OBJECTIVES: Sex work sites have been hypothesised to be at the root of the observed heterogeneity in HIV prevalence in sub-Saharan Africa. We determined if proximity to sex work sites is associated with HIV prevalence among the general population in Zimbabwe, a country with one of the highest HIV prevalence in the world. METHODS: In this cross-sectional study we use a unique combination of nationally representative geolocated individual-level data from 16,121 adults (age 15-49 years) from 400 sample locations and the locations of 55 sex work sites throughout Zimbabwe; covering an estimated 95% of all female sex workers (FSWs). We calculated the shortest distance by road from each survey sample location to the nearest sex work site, for all sites and by type of sex work site, and conducted univariate and multivariate multilevel logistic regressions to determine the association between distance to sex work sites and HIV seropositivity, controlling for age, sex, male circumcision status, number of lifetime sex partners, being a FSW client or being a stable partner of an FSW client. RESULTS: We found no significant association between HIV seroprevalence and proximity to the nearest sex work site among the general population in Zimbabwe, regardless of which type of site is closest (city site adjusted odds ratio [aOR] 1.010 [95% confidence interval {CI} 0.992-1.028]; economic growth point site aOR 0.982 [95% CI 0.962-1.002]; international site aOR 0.995 [95% CI 0.979-1.012]; seasonal site aOR 0.987 [95% CI 0.968-1.006] and transport site aOR 1.007 [95% CI 0.987-1.028]). Individual-level indicators of sex work were significantly associated with HIV seropositivity: being an FSW client (aOR 1.445 [95% CI 1.188-1.745]); nine or more partners versus having one to three lifetime partners (aOR 2.072 [95% CI 1.654-2.596]). CONCLUSIONS: Sex work sites do not seem to directly affect HIV prevalence among the general population in surrounding areas. Prevention and control interventions for HIV at these locations should primarily focus on sex workers and their clients, with special emphasis on including and retaining mobile sex workers and clients into services.
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Infecções por HIV , Soropositividade para HIV , Profissionais do Sexo , Adolescente , Adulto , Estudos Transversais , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Soroepidemiológicos , Trabalho Sexual , Local de Trabalho , Adulto Jovem , Zimbábue/epidemiologiaRESUMO
Increased coverage of voluntary medical male circumcision (VMMC) is needed in countries with high HIV prevalence. We applied an HIV-prevention cascade to identify gaps in male circumcision coverage in Zambia. We used survey data collected in 2013 and 2014/15 to describe circumcision coverage at each time-point, and prevalence of variables related to demand for and supply of VMMC. We explored whether circumcision coverage in 2014/15 was associated with demand and supply among uncircumcised men in 2013. Results show that circumcision coverage was 11.5% in 2013 and 18.0% in 2014/15. Levels of having heard of circumcision and agreeing with prevention benefits was similar at both time-points (79.8% vs 83.2%, and 49.7% vs 50.7%, respectively). In 2013, 39.3% of men perceived services to be available compared to 54.7% in 2014/15. Levels of having heard of circumcision in 2013 was correlated with and higher perceived service availability associated with coverage in 2014/15. VMMC coverage was low in these study sites. Knowledge of prevention tools and of service availability are necessary to increase coverage but alone are insufficient.
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Circuncisão Masculina , Atenção à Saúde/organização & administração , Infecções por HIV/prevenção & controle , Serviços Preventivos de Saúde/organização & administração , Adolescente , Adulto , Circuncisão Masculina/estatística & dados numéricos , Análise por Conglomerados , Humanos , Masculino , Pessoa de Meia-Idade , Aceitação pelo Paciente de Cuidados de Saúde , População Rural , Programas Voluntários , Adulto Jovem , Zâmbia/epidemiologiaRESUMO
Friends could be influential on young women's sexual health via influences on sexual behaviours and as connections to sexual partners, but are understudied in sub-Saharan Africa. We cross-sectionally surveyed 2326 13-20 year-old young women eligible for grades 8-11 in rural South Africa about their sexual behaviour and up to three sexual partners. Participants each described five specific but unidentified friends and the relationships between them in an 'egocentric' network analysis design. We used logistic regression to investigate associations between friendship characteristics and participants' reports of ever having had sex (n = 2326) and recent condom use (n = 457). We used linear regression with random effects by participant to investigate friendship characteristics and age differences with sexual partners (n = 633 participants, 1051 partners). We found that it was common for friends to introduce young women to those who later became sexual partners, and having older friends was associated with having older sexual partners, (increase of 0.37 years per friend at least 1 year older, 95% CI 0.21-0.52, adjusted). Young women were more likely to report ever having had sex when more friends were perceived to be sexually active (adjusted OR 1.85, 95% CI 1.72-2.01 per friend) and when they discussed sex, condoms and HIV with friends. Perception of friends' condom use was not associated with participants' reported condom use. While this study is preliminary and unique in this population and further research should be conducted, social connections between friends and sexual partners and perceptions of friend sexual behaviours could be considered in the design of sexual health interventions for young women in South Africa.
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Amigos/psicologia , Comportamento Sexual/psicologia , Comportamento Sexual/estatística & dados numéricos , Parceiros Sexuais/psicologia , Adolescente , Preservativos , Estudos Transversais , Feminino , Humanos , Modelos Logísticos , População Rural , Sexo Seguro/psicologia , Sexo Seguro/estatística & dados numéricos , África do Sul/epidemiologia , Adulto JovemRESUMO
Young female sex-workers (FSW) aged 18-24 are at high risk of HIV due to high numbers of sexual partners, difficulty negotiating condom use, increased risk of gender-based violence, and limited access to services. Here we describe changes in sexual behaviours among young FSW across Zimbabwe between 2013 and 2016, and risk factors for prevalent HIV in 2013 and 2016. FSW ≥ 18 years were recruited using respondent-driven sampling in 14 sites across Zimbabwe in 2013 and 2016 as part of the SAPPH-IRe trial. We collected data on socio-demographics and sexual behaviour and offered HIV testing. Statistical analyses were RDS-II weighted. Characteristics of young FSW aged 18-24 were described, stratified by age. Logistic regression was used to assess difference in sexual behaviours by reported HIV status between 2013 and 2016, and to explore associations with prevalent HIV in 2013 and 2016. 656 young FSW were recruited in 2013 and 503 in 2016. Characteristics of young FSW were similar across both surveys. HIV prevalence was similar at both time points (35% vs 36%) and rose steeply with age. Compared to young FSW in 2013, reported condom-less sex with a steady partner and condom-less sex with clients was higher in 2016 among women self-reporting HIV negative status (OR = 6.41; 95%CI: 3.40-12.09; P<0.001) and (OR = 1.69; 95%CI: 1.14-2.51, P = 0.008), respectively, but not among young FSW self-reporting HIV positive status (OR = 2.35; 95%CI: 0.57-9.76; P = 0.236) and (OR = 1.87; 95%CI: 0.74-4.74; P = 0.186). After adjusting for age in 2016, young FSW who had ever been married had increased odds of testing HIV positive (OR = 1.88; 95% CI 1.04-3.39; P = 0.036) compared with those who had never married. Young FSW who completed secondary education or higher were less likely to test HIV positive (OR = 0.41; 95% CI 0.20-0.83; P = 0.012) compared with those with primary education or less. Young FSW remain at very high risk of HIV. Strategies to identify young FSW when they first start selling and refer them into services that address their economic, social and sexual vulnerabilities are critical.
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Infecções por HIV/transmissão , Abuso Físico/estatística & dados numéricos , Profissionais do Sexo/estatística & dados numéricos , Parceiros Sexuais/psicologia , Sexo sem Proteção/estatística & dados numéricos , Adolescente , Estudos Transversais , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Profissionais do Sexo/psicologia , Fatores de Tempo , Adulto Jovem , Zimbábue/epidemiologiaRESUMO
BACKGROUND: National estimates of the sizes of key populations, including female sex workers, men who have sex with men, and transgender women are critical to inform national and international responses to the HIV pandemic. However, epidemiologic studies typically provide size estimates for only limited high priority geographic areas. This article illustrates a two-stage approach to obtain a national key population size estimate in the Dominican Republic using available estimates and publicly available contextual information. METHODS: Available estimates of key population size in priority areas were augmented with targeted additional data collection in other areas. To combine information from data collected at each stage, we used statistical methods for handling missing data, including inverse probability weights, multiple imputation, and augmented inverse probability weights. RESULTS: Using the augmented inverse probability weighting approach, which provides some protection against parametric model misspecification, we estimated that 3.7% (95% CI = 2.9, 4.7) of the total population of women in the Dominican Republic between the ages of 15 and 49 years were engaged in sex work, 1.2% (95% CI = 1.1, 1.3) of men aged 15-49 had sex with other men, and 0.19% (95% CI = 0.17, 0.21) of people assigned the male sex at birth were transgender. CONCLUSIONS: Viewing the size estimation of key populations as a missing data problem provides a framework for articulating and evaluating the assumptions necessary to obtain a national size estimate. In addition, this paradigm allows use of methods for missing data familiar to epidemiologists.
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Demografia/métodos , Densidade Demográfica , Adolescente , Adulto , Interpretação Estatística de Dados , República Dominicana/epidemiologia , Medidas em Epidemiologia , Feminino , Homossexualidade Masculina/estatística & dados numéricos , Humanos , Masculino , Pessoa de Meia-Idade , Projetos de Pesquisa , Trabalho Sexual/estatística & dados numéricos , Pessoas Transgênero/estatística & dados numéricos , Adulto JovemRESUMO
Background: The COVID-19 pandemic both relied and placed significant burdens on the experts involved from research and public health sectors. The sustained high pressure of a pandemic on responders, such as healthcare workers, can lead to lasting psychological impacts including acute stress disorder, post-traumatic stress disorder, burnout, and moral injury, which can impact individual wellbeing and productivity. Methods: As members of the infectious disease modelling community, we convened a reflective workshop to understand the professional and personal impacts of response work on our community and to propose recommendations for future epidemic responses. The attendees represented a range of career stages, institutions, and disciplines. This piece was collectively produced by those present at the session based on our collective experiences. Results: Key issues we identified at the workshop were lack of institutional support, insecure contracts, unequal credit and recognition, and mental health impacts. Our recommendations include rewarding impactful work, fostering academia-public health collaboration, decreasing dependence on key individuals by developing teams, increasing transparency in decision-making, and implementing sustainable work practices. Conclusions: Despite limitations in representation, this workshop provided valuable insights into the UK COVID-19 modelling experience and guidance for future public health crises. Recognising and addressing the issues highlighted is crucial, in our view, for ensuring the effectiveness of epidemic response work in the future.
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BACKGROUND: Key population HIV programmes in sub-Saharan Africa require epidemiological information to ensure equitable and universal access to effective services. We aimed to consolidate and harmonise survey data among female sex workers, men who have sex with men, people who inject drugs, and transgender people to estimate key population size, HIV prevalence, and antiretroviral therapy (ART) coverage for countries in mainland sub-Saharan Africa. METHODS: Key population size estimates, HIV prevalence, and ART coverage data from 39 sub-Saharan Africa countries between 2010 and 2023 were collated from existing databases and verified against source documents. We used Bayesian mixed-effects spatial regression to model urban key population size estimates as a proportion of the gender-matched, year-matched, and area-matched population aged 15-49 years. We modelled subnational key population HIV prevalence and ART coverage with age-matched, gender-matched, year-matched, and province-matched total population estimates as predictors. FINDINGS: We extracted 2065 key population size data points, 1183 HIV prevalence data points, and 259 ART coverage data points. Across national urban populations, a median of 1·65% (IQR 1·35-1·91) of adult cisgender women were female sex workers, 0·89% (0·77-0·95) were men who have sex with men, 0·32% (0·31-0·34) were men who injected drugs, and 0·10% (0·06-0·12) were women who were transgender. HIV prevalence among key populations was, on average, four to six times higher than matched total population prevalence, and ART coverage was correlated with, but lower than, the total population ART coverage with wide heterogeneity in relative ART coverage across studies. Across sub-Saharan Africa, key populations were estimated as comprising 1·2% (95% credible interval 0·9-1·6) of the total population aged 15-49 years but 6·1% (4·5-8·2) of people living with HIV. INTERPRETATION: Key populations in sub-Saharan Africa experience higher HIV prevalence and lower ART coverage, underscoring the need for focused prevention and treatment services. In 2024, limited data availability and heterogeneity constrain precise estimates for programming and monitoring trends. Strengthening key population surveys and routine data within national HIV strategic information systems would support more precise estimates. FUNDING: UNAIDS, Bill & Melinda Gates Foundation, and US National Institutes of Health.
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Infecções por HIV , Humanos , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , África Subsaariana/epidemiologia , Feminino , Adulto , Masculino , Prevalência , Adolescente , Adulto Jovem , Pessoa de Meia-Idade , Profissionais do Sexo/estatística & dados numéricos , Densidade Demográfica , Antirretrovirais/uso terapêutico , Pessoas Transgênero/estatística & dados numéricos , Teorema de Bayes , Homossexualidade Masculina/estatística & dados numéricosRESUMO
Testing for infection with SARS-CoV-2 is an important intervention in reducing onwards transmission of COVID-19, particularly when combined with the isolation and contact-tracing of positive cases. Many countries with the capacity to do so have made use of lab-processed Polymerase Chain Reaction (PCR) testing targeted at individuals with symptoms and the contacts of confirmed cases. Alternatively, Lateral Flow Tests (LFTs) are able to deliver a result quickly, without lab-processing and at a relatively low cost. Their adoption can support regular mass asymptomatic testing, allowing earlier detection of infection and isolation of infectious individuals. In this paper we extend and apply the agent-based epidemic modelling framework Covasim to explore the impact of regular asymptomatic testing on the peak and total number of infections in an emerging COVID-19 wave. We explore testing with LFTs at different frequency levels within a population with high levels of immunity and with background symptomatic PCR testing, case isolation and contact tracing for testing. The effectiveness of regular asymptomatic testing was compared with 'lockdown' interventions seeking to reduce the number of non-household contacts across the whole population through measures such as mandating working from home and restrictions on gatherings. Since regular asymptomatic testing requires only those with a positive result to reduce contact, while lockdown measures require the whole population to reduce contact, any policy decision that seeks to trade off harms from infection against other harms will not automatically favour one over the other. Our results demonstrate that, where such a trade off is being made, at moderate rates of early exponential growth regular asymptomatic testing has the potential to achieve significant infection control without the wider harms associated with additional lockdown measures.
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COVID-19 , Humanos , COVID-19/epidemiologia , SARS-CoV-2 , Teste para COVID-19 , Controle de Doenças Transmissíveis , Busca de Comunicante/métodosRESUMO
Variability in case severity and in the range of symptoms experienced has been apparent from the earliest months of the COVID-19 pandemic. From a clinical perspective, symptom variability might indicate various routes/mechanisms by which infection leads to disease, with different routes requiring potentially different treatment approaches. For public health and control of transmission, symptoms in community cases were the prompt upon which action such as PCR testing and isolation was taken. However, interpreting symptoms presents challenges, for instance, in balancing the sensitivity and specificity of individual symptoms with the need to maximise case finding, whilst managing demand for limited resources such as testing. For both clinical and transmission control reasons, we require an approach that allows for the possibility of distinct symptom phenotypes, rather than assuming variability along a single dimension. Here we address this problem by bringing together four large and diverse datasets deriving from routine testing, a population-representative household survey and participatory smartphone surveillance in the United Kingdom. Through the use of cutting-edge unsupervised classification techniques from statistics and machine learning, we characterise symptom phenotypes among symptomatic SARS-CoV-2 PCR-positive community cases. We first analyse each dataset in isolation and across age bands, before using methods that allow us to compare multiple datasets. While we observe separation due to the total number of symptoms experienced by cases, we also see a separation of symptoms into gastrointestinal, respiratory and other types, and different symptom co-occurrence patterns at the extremes of age. In this way, we are able to demonstrate the deep structure of symptoms of COVID-19 without usual biases due to study design. This is expected to have implications for the identification and management of community SARS-CoV-2 cases and could be further applied to symptom-based management of other diseases and syndromes.
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COVID-19 , Humanos , COVID-19/diagnóstico , COVID-19/epidemiologia , SARS-CoV-2/genética , Pandemias/prevenção & controle , Teste para COVID-19 , Sensibilidade e EspecificidadeRESUMO
Introduction: The Global AIDS Strategy 2021-2026 calls for equitable and equal access to HIV prevention and treatment programmes for all populations to reduce HIV incidence and end HIV/AIDS as a public health threat by 2030. Transgender populations (TGP), including transmen (TGM) and transwomen (TGW) are populations that have been marginalised and are at high risk of HIV infection in sub-Saharan Africa (SSA). Limited surveillance data on HIV among TGP are available in the region to guide programmatic responses and policymaking. Surveillance data on cisgender men who have sex with men (cis-MSM) are comparatively abundant and may be used to infer TGP HIV prevalence. Methods: Data from key population surveys conducted in SSA between 2010-2022 were identified from existing databases and survey reports. Studies that collected HIV prevalence on both TGP and cis-MSM populations were analysed in a random effect meta-analysis to estimate the ratio of cis-MSM:TGW HIV prevalence. Results: Eighteen studies were identified encompassing 8,052 TGW and 19,492 cis-MSM. TGW HIV prevalence ranged from 0-71.6% and cis-MSM HIV prevalence from 0.14-55.7%. HIV prevalence in TGW was 50% higher than in cis-MSM (prevalence ratio (PR) 1.50 95% CI 1.26-1.79). TGW HIV prevalence was highly correlated with year/province-matched cis-MSM HIV prevalence (R2 = 0.62), but poorly correlated with year/province-matched total population HIV prevalence (R2 = 0.1). Five TGM HIV prevalence estimates were identified ranging from 1-24%. Insufficient TGM data were available to estimate cis-MSM:TGM HIV prevalence ratios. Conclusion: Transgender women experience a significantly greater HIV burden than cis-MSM in SSA. Bio-behavioural surveys designed and powered to measure determinants of HIV infection, treatment coverage, and risk behaviours among transgender populations, distinct from cis-MSM, will improve understanding of HIV risk and vulnerabilities among TGP and support improved programmes.
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The outbreak of monkeypox across non-endemic regions confirmed in May 2022 shows epidemiological features distinct from previously imported outbreaks, most notably its observed growth and predominance amongst men who have sex with men (MSM). We use a transmission model fitted to empirical sexual partnership data to show that the heavy-tailed sexual partnership distribution, in which a handful of individuals have disproportionately many partners, can explain the sustained growth of monkeypox among MSM despite the absence of such patterns previously. We suggest that the basic reproduction number (R0) for monkeypox over the MSM sexual network may be substantially above 1, which poses challenges to outbreak containment. Ensuring support and tailored messaging to facilitate prevention and early detection among MSM with high numbers of partners is warranted.
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Surtos de Doenças , Homossexualidade Masculina , Mpox , Rede Social , Surtos de Doenças/prevenção & controle , Humanos , Masculino , Mpox/epidemiologia , Mpox/transmissão , Análise de Rede SocialRESUMO
Men who have sex with men (MSM) in Kenya bear a heavy burden of HIV/STIs and are a priority population in the national HIV/AIDS response, yet remain criminalised and stigmatised within society. HIV pre-exposure prophylaxis (PrEP) offers an opportunity to significantly impact the HIV epidemic, as does the concept of U = U, whereby those who are living with HIV and on treatment are uninfectious when their viral load has been suppressed so as to be undetectable. However, the value of such innovations will not be realised without sufficient understanding of, and respect for, the sexual health service provision needs of MSM. This paper describes findings from 30 in-depth interviews with MSM living in Nairobi that explored engagement with sexual health service providers, barriers to access and perceived opportunities to improve service design and delivery. Findings indicate concern relating to the professionalism of some staff working within public hospitals as well as feelings that many sexual health services were not considered safe spaces for the discussion of MSM-specific sexual behaviour. Diverse views were expressed relating to comfort in public, community and private sexual health services as well as how these are and should be organised.
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Infecções por HIV , Profilaxia Pré-Exposição , Minorias Sexuais e de Gênero , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Homossexualidade Masculina , Humanos , Quênia , Masculino , Comportamento SexualRESUMO
INTRODUCTION: Young female sex workers (FSW) are disproportionately vulnerable to HIV. Zimbabwe data show higher HIV incidence and lower engagement in services compared to older FSW. Utilizing data from a combination HIV prevention and treatment intervention, we describe engagement in the HIV services over time among FSW 18-24 years, compared to those ≥25 years of age. MATERIALS AND METHODS: Data were collected via respondent-driven sampling (RDS) surveys in 14 communities in 2013 and 2016, with >2500 FSW per survey. They included blood samples for HIV and viral load testing. As the intervention had no significant impact on HIV care cascade outcomes, data were aggregated across study arms. Analyses used RDS-II estimation. RESULTS: Mean age in 2013 and 2016 was 31 and 33 years, with 27% and 17% aged 18-24 years. Overall HIV prevalence was 59% at each timepoint, and 35% and 36% among younger FSW. From 2013 to 2016 there was an increase in young HIV-positive FSW knowing their status (38% vs 60%, OR = 2.51, p<0.01). Outcomes for all FSW improved significantly over time at all steps of the cascade, and the relative change over time was similar among older versus younger FSW for most cascade variables. DISCUSSION: Young FSW had improvements in care cascade outcomes, and proportionate improvements similar to older FSW, yet they remain less engaged in services overall. This implies that the dedicated FSW services in Zimbabwe are having a comparably positive impact across age groups, however more is likely required to address young FSW's unique vulnerabilities and needs.
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Infecções por HIV , Profissionais do Sexo , Adulto , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Humanos , Prevalência , Carga Viral , Zimbábue/epidemiologiaRESUMO
BACKGROUND: To reduce HIV incidence among adolescent girls who sell sex (AGSS) in Zimbabwe, we need to better understand how vulnerabilities intersect with HIV infection and how those living with HIV engage in care. METHODS: In 2017, we conducted social mapping in 4 locations in Zimbabwe and recruited girls aged 16-19 years who sell sex, using respondent-driven sampling or census sampling methods. Participants completed a questionnaire and provided finger prick blood samples for HIV antibody testing. RESULTS: Of 605 AGSS recruited, 74.4% considered themselves sex workers, 24.4% reported experiencing violence in the past year, 91.7% were not in school, and 83.8% had less than a complete secondary education. Prevalence of HIV increased steeply from 2.1% among those aged 16 years to 26.9% among those aged 19 years; overall, 20.2% of AGSS were HIV-positive. In the multivariate analysis, age, education, marital status, and violence from a client were associated with HIV. Among the 605 AGSS, 86.3% had ever tested for HIV, with 64.1% having tested in the past 6 months. Among AGSS living with HIV, half (50.8%) were aware of their status, among whom 83.9% reported taking antiretroviral therapy. CONCLUSION: The steep rise in HIV prevalence among those aged between 16 and 19 years suggests the window to engage with AGSS before HIV acquisition is short. To accelerate reductions in incidence among AGSS, intensified combination prevention strategies that address structural factors and tailor services to the needs of AGSS are required, particularly ensuring girls enroll and remain in school.
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Infecções por HIV , Profissionais do Sexo , Adolescente , Adulto , Coito , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Humanos , Prevalência , Comportamento Sexual , Adulto Jovem , Zimbábue/epidemiologiaRESUMO
Mathematical modelling and statistical inference provide a framework to evaluate different non-pharmaceutical and pharmaceutical interventions for the control of epidemics that has been widely used during the COVID-19 pandemic. In this paper, lessons learned from this and previous epidemics are used to highlight the challenges for future pandemic control. We consider the availability and use of data, as well as the need for correct parameterisation and calibration for different model frameworks. We discuss challenges that arise in describing and distinguishing between different interventions, within different modelling structures, and allowing both within and between host dynamics. We also highlight challenges in modelling the health economic and political aspects of interventions. Given the diversity of these challenges, a broad variety of interdisciplinary expertise is needed to address them, combining mathematical knowledge with biological and social insights, and including health economics and communication skills. Addressing these challenges for the future requires strong cross-disciplinary collaboration together with close communication between scientists and policy makers.
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COVID-19 , Pandemias , COVID-19/epidemiologia , Humanos , SARS-CoV-2RESUMO
BACKGROUND: Transgender people are disproportionately affected by HIV and other sexually transmitted infections (STIs) worldwide, and culturally competent prevention and treatment services are often unavailable or inaccessible. Despite recent improvements in national HIV responses for many key populations in east Africa, evidence of effective responses informed by transgender sexual health needs is sparse. We aimed to assess gender identity among men and transgender people who have sex with men in Kenya, and to explore its associations with sexual health-related outcomes, risk behaviours, and uptake of HIV prevention and care interventions. METHODS: We did a cross-sectional study in Nairobi, Kenya, and recruited adult cisgender men and transfeminine people who reported having sex with men, through respondent-driven sampling. Inclusion criteria were possession of a valid study coupon, being aged 18 years or older, having male sex assignment at birth or male gender identification currently, living within 50 km of Nairobi, and having had consensual anal or oral sexual activity with a man in the previous 12 months. Seed participants were identified by three community organisations that provide targeted health-care services to gay, bisexual, or other men who have sex with men (MSM) communities in Nairobi. We assessed gender identity, sociodemographics, sexual behaviour, and HIV prevention and care uptake, by self-completed survey. Participants were tested for HIV, syphilis, and rectal and urethral gonorrhoea and chlamydia. We compared prevalence of sexual health outcomes, risk behaviour, and HIV prevention and care service uptake among transfeminine and cisgender participants, using multivariable robust Poisson regression models, with gender identity as the independent variable. FINDINGS: Between May 4 and Dec 8, 2017, we enrolled 618 participants. Six participants did not answer the questions on sex assigned at birth and gender identity and so were excluded from the analyses. 522 (sample-weighted percentage 86%) of 612 participants were classified as cisgender men, 70 (11%) as transfeminine, and three (<1%) as transmasculine. 17 participants (2%) did not identify as male, female, or transgender. Compared with cisgender men, transfeminine people were more likely to be HIV-positive (28 [41%] of 70 transfeminine vs 151 [25%] of 521 cisgender men; p=0·0009) and to report current symptoms consistent with a rectal STI (eight [16%] of 67 vs 38 [7%] of 518; p=0·014). Transfeminine people reported higher numbers of recent male sexual partners (22 [27%] of 70 transfeminine people reported four or more male sexual partners in the past 3 months vs 112 [13%] of 522 cisgender men; p=0·042) and were more likely to report condomless anal intercourse with men (43 [62%] of 70 vs 208 [39%] of 522; p=0·0009) and receptive anal intercourse (54 [76%] of 70 vs 252 [46%] of 522; p<0·0001) in the past 3 months, and transactional sex with men (42 [57%] of 69 vs 240 [42%] of 518; p=0·023) and experience of sexual assault (16 [23%] of 69 vs 65 [11%] of 520; p=0·019) in the past 12 months. Use of pre-exposure prophylaxis and post-exposure prophylaxis was low in both groups. INTERPRETATION: Transfeminine people who have sex with men have a higher burden of HIV and associated risk behaviours compared with cisgender MSM in the same context, yet their uptake of prevention and care services is poor. Policies should acknowledge the specific needs of transfeminine people as distinct from cisgender MSM, and support health-care providers to address these needs. FUNDING: Evidence for HIV Prevention in Southern Africa (EHPSA), UK Aid.
Assuntos
Fármacos Anti-HIV/uso terapêutico , Infecções por HIV/epidemiologia , Infecções por HIV/psicologia , Homossexualidade Masculina/psicologia , Pessoas Transgênero/psicologia , Adolescente , Adulto , Terapia Antirretroviral de Alta Atividade , Estudos Transversais , Feminino , Identidade de Gênero , HIV/patogenicidade , Infecções por HIV/tratamento farmacológico , Infecções por HIV/transmissão , Humanos , Quênia/epidemiologia , Masculino , Pessoa de Meia-Idade , Profilaxia Pós-Exposição/ética , Profilaxia Pré-Exposição/ética , Parceiros Sexuais/psicologia , Minorias Sexuais e de Gênero/psicologia , Resultado do TratamentoRESUMO
We explore strategies of contact tracing, case isolation and quarantine of exposed contacts to control the SARS-CoV-2 epidemic using a branching process model with household structure. This structure reflects higher transmission risks among household members than among non-household members. We explore strategic implementation choices that make use of household structure, and investigate strategies including two-step tracing, backwards tracing, smartphone tracing and tracing upon symptom report rather than test results. The primary model outcome is the effect of contact tracing, in combination with different levels of physical distancing, on the growth rate of the epidemic. Furthermore, we investigate epidemic extinction times to indicate the time period over which interventions must be sustained. We consider effects of non-uptake of isolation/quarantine, non-adherence, and declining recall of contacts over time. Our results find that, compared to self-isolation of cases without contact tracing, a contact tracing strategy designed to take advantage of household structure allows for some relaxation of physical distancing measures but cannot completely control the epidemic absent of other measures. Even assuming no imported cases and sustainment of moderate physical distancing, testing and tracing efforts, the time to bring the epidemic to extinction could be in the order of months to years. This article is part of the theme issue 'Modelling that shaped the early COVID-19 pandemic response in the UK'.
Assuntos
COVID-19/epidemiologia , Modelos Teóricos , Pandemias , SARS-CoV-2/patogenicidade , COVID-19/transmissão , COVID-19/virologia , Busca de Comunicante/métodos , Características da Família , Humanos , Quarentena/métodosRESUMO
Early assessments of the growth rate of COVID-19 were subject to significant uncertainty, as expected with limited data and difficulties in case ascertainment, but as cases were recorded in multiple countries, more robust inferences could be made. Using multiple countries, data streams and methods, we estimated that, when unconstrained, European COVID-19 confirmed cases doubled on average every 3 days (range 2.2-4.3 days) and Italian hospital and intensive care unit admissions every 2-3 days; values that are significantly lower than the 5-7 days dominating the early published literature. Furthermore, we showed that the impact of physical distancing interventions was typically not seen until at least 9 days after implementation, during which time confirmed cases could grow eightfold. We argue that such temporal patterns are more critical than precise estimates of the time-insensitive basic reproduction number R0 for initiating interventions, and that the combination of fast growth and long detection delays explains the struggle in countries' outbreak response better than large values of R0 alone. One year on from first reporting these results, reproduction numbers continue to dominate the media and public discourse, but robust estimates of unconstrained growth remain essential for planning worst-case scenarios, and detection delays are still key in informing the relaxation and re-implementation of interventions. This article is part of the theme issue 'Modelling that shaped the early COVID-19 pandemic response in the UK'.