Population size, HIV prevalence, and antiretroviral therapy coverage among key populations in sub-Saharan Africa: collation and synthesis of survey data, 2010-23.

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.

Diversity of symptom phenotypes in SARS-CoV-2 community infections observed in multiple large datasets.

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.

HIV prevalence in transgender populations and cisgender men who have sex with men in sub-Saharan Africa 2010-2022: a meta-analysis.

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.

Effectiveness of testing, contact tracing and isolation interventions among the general population on reducing transmission of SARS-CoV-2: a systematic review.

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.

The role of regular asymptomatic testing in reducing the impact of a COVID-19 wave.

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.

Accumulation of Immunity in Heavy-Tailed Sexual Contact Networks Shapes Mpox Outbreak Sizes.

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.

Heavy-tailed sexual contact networks and monkeypox epidemiology in the global outbreak, 2022.

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 () for monkeypox over the MSM sexual network may be substantially above 1, which poses challenges to outbreak containment.

Engagement in HIV services over time among young women who sell sex in Zimbabwe.

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.

No increased HIV risk in general population near sex work sites: A nationally representative cross-sectional study in Zimbabwe.

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).

Brief Report: Adolescent Girls Who Sell Sex in Zimbabwe: HIV Risk, Behaviours, and Service Engagement.

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.

Challenges for modelling interventions for future pandemics.

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.

Experiences and challenges in sexual health service access among men who have sex with men in Kenya.

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.

Challenges in control of COVID-19: short doubling time and long delay to effect of interventions.

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.

Using a household-structured branching process to analyse contact tracing in the SARS-CoV-2 pandemic.

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.

HIV burden and correlates of infection among transfeminine people and cisgender men who have sex with men in Nairobi, Kenya: an observational study.

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.

Public target interventions to reduce the inappropriate use of medicines or medical procedures: a systematic review.

Background: An epidemic of health disorders can be triggered by a collective manifestation of inappropriate behaviors, usually systematically fueled by non-medical factors at the individual and/or societal levels. This study aimed to (1) landscape and assess the evidence on interventions that reduce inappropriate demand of medical resources (medicines or procedures) by triggering behavioral change among healthcare consumers, (2) map out intervention components that have been tried and tested, and (3) identify the "active ingredients" of behavior change interventions that were proven to be effective in containing epidemics of inappropriate use of medical resources.

Methods: For this systematic review, we searched MEDLINE, EMBASE, the Cochrane Library, and PsychINFO from the databases' inceptions to May 2019, without language restrictions, for behavioral intervention studies.

Online socializing among men who have sex with men and transgender people in Nairobi and Johannesburg and implications for public health-related research and health promotion: an analysis of qualitative and respondent-driven sampling survey data.

Introduction: There is little published literature about gay, bisexual and other men who have sex with men and transgender individuals (MSM and TG)'s use of social media in sub-Saharan Africa, despite repressive social and/or criminalizing contexts that limit access to physical HIV prevention. We sought to describe MSM and TG's online socializing in Nairobi and Johannesburg, identifying the characteristics of those socializing online and those not, in order to inform the development of research and health promotion in online environments.

Methods: Respondent-driven sampling surveys were conducted in 2017 in Nairobi (n = 618) and Johannesburg (n = 301) with those reporting current male gender identity or male sex assigned at birth and sex with a man in the last 12 months.

Decisions to use antibiotics for upper respiratory tract infections across China: a large-scale cross-sectional survey among university students.

Objectives: To investigate the decision-making process of Chinese university students with respect to antibiotic use for upper respiratory tract infections (URTIs).

Design: A cross-sectional questionnaire study.

Setting: The participants recruited from six universities across all Chinese regions from September to November 2015.

Using statistics and mathematical modelling to understand infectious disease outbreaks: COVID-19 as an example.

During an infectious disease outbreak, biases in the data and complexities of the underlying dynamics pose significant challenges in mathematically modelling the outbreak and designing policy. Motivated by the ongoing response to COVID-19, we provide a toolkit of statistical and mathematical models beyond the simple SIR-type differential equation models for analysing the early stages of an outbreak and assessing interventions. In particular, we focus on parameter estimation in the presence of known biases in the data, and the effect of non-pharmaceutical interventions in enclosed subpopulations, such as households and care homes.

HIV testing, care and viral suppression among men who have sex with men and transgender individuals in Johannesburg, South Africa.

Introduction: Men who have sex with men and transgender individuals (MSM/TG) carry a disproportionately high burden of HIV, including in South Africa. However, there are few empirical population-representative estimates of viral suppression and the HIV care cascade including HIV testing among this population, nor of factors associated with these outcomes.

Methods: We conducted a respondent driven sampling (RDS) survey among 301 MSM/TG in Johannesburg in 2017.

Assessing Bias in Population Size Estimates Among Hidden Populations When Using the Service Multiplier Method Combined With Respondent-Driven Sampling Surveys: Survey Study.

Background: Population size estimates (PSEs) for hidden populations at increased risk of HIV, including female sex workers (FSWs), are important to inform public health policy and resource allocation. The service multiplier method (SMM) is commonly used to estimate the sizes of hidden populations. We used this method to obtain PSEs for FSWs at 9 sites in Zimbabwe and explored methods for assessing potential biases that could arise in using this approach.

Estimating the Population Size of Female Sex Workers in Zimbabwe: Comparison of Estimates Obtained Using Different Methods in Twenty Sites and Development of a National-Level Estimate.

Background: National-level population size estimates (PSEs) for hidden populations are required for HIV programming and modelling. Various estimation methods are available at the site-level, but it remains unclear which are optimal and how best to obtain national-level estimates.

Setting: Zimbabwe.

HIV prevention cascades: A unifying framework to replicate the successes of treatment cascades.

Many countries are off track to meet targets for reducing new HIV infections. HIV prevention cascades have been proposed to assist in the implementation and monitoring of HIV prevention programmes by identifying gaps in the steps required for effective use of prevention methods, similar to HIV treatment cascades. However, lack of a unifying framework impedes widespread use of prevention cascades.