May 2024
·
88 Reads
The Lancet
This page lists the scientific contributions of an author, who either does not have a ResearchGate profile, or has not yet added these contributions to their profile.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
May 2024
·
88 Reads
The Lancet
June 2020
·
69 Reads
·
8 Citations
Introduction To achieve significant progress in global HIV prevention from 2020 onward, it is essential to ensure that appropriate programmes are being delivered with high quality and sufficient intensity and scale and then taken up by the people who most need and want them in order to have both individual and public health impact. Yet, currently, there is no standard way of assessing this. Available HIV prevention indicators do not provide a logical set of measures that combine to show reduction in HIV incidence and allow for comparison of success (or failure) of HIV prevention programmes and for monitoring progress in meeting global targets. To redress this, attention increasingly has turned to the prospects of devising an HIV prevention cascade, similar to the now‐standard HIV treatment cascade; but this has proven to be a controversial enterprise, chiefly due to the complexity of primary prevention. Discussion We address a number of core issues attendant with devising prevention cascades, including: determining the population of interest and accounting for the variability and fluidity of HIV‐related risk within it; the fact that there are multiple HIV prevention methods, and many people are exposed to a package of them, rather than a single method; and choosing the final step (outcome) in the cascade. We propose two unifying models of prevention cascades‐one more appropriate for programme managers and monitors and the other for researchers and programme developers‐and note their relationship. We also provide some considerations related to cascade data quality and improvement. Conclusions The HIV prevention field has been grappling for years with the idea of developing a standardised way to regularly assess progress and to monitor and improve programmes accordingly. The cascade provides the potential to do this, but it is complicated and highly nuanced. We believe the two models proposed here reflect emerging consensus among the range of stakeholders who have been engaging in this discussion and who are dedicated to achieving global HIV prevention goals by ensuring the most appropriate and effective programmes and methods are supported.
June 2020
·
71 Reads
·
21 Citations
The Journal of Infectious Diseases
Background: Although effective, some oral pre-exposure prophylaxis (PrEP) users face barriers to adherence using daily pills, which could be reduced by long-acting formulations. Long-acting cabotegravir (CAB LA) is a potential new injectable formulation for HIV PrEP being tested in Phase III trials. Methods: We use a mathematical model of the HIV epidemic in South Africa to simulate CAB LA uptake by population groups with different levels of HIV risk. We compare the trajectory of the HIV epidemic until 2050 with and without CAB LA to estimate the impact of the intervention. Results: Delivering CAB LA to 10% of the adult population could avert more than 15% of new infections from 2023-2050. The impact would be lower but more efficient if delivered to populations at higher HIV risk: 127 person-years of CAB LA use would be required to avert one HV infection within five years if used by all adults and 47 if used only by the highest risk women.
February 2020
·
228 Reads
·
34 Citations
The Lancet HIV
Background: The rapid scale-up of antiretroviral therapy (ART) towards the UNAIDS 90-90-90 goals over the last decade has sparked considerable debate as to whether universal test and treat can end the HIV-1 epidemic in sub-Saharan Africa. We aimed to develop a network transmission model, calibrated to capture age-specific and sex-specific gaps in the scale-up of ART, to estimate the historical and future effect of attaining and surpassing the UNAIDS 90-90-90 treatment targets on HIV-1 incidence and mortality, and to assess whether these interventions will be enough to achieve epidemic control (incidence of 1 infection per 1000 person-years) by 2030. Methods: We used eSwatini (formerly Swaziland) as a case study to develop our model. We used data on HIV prevalence by 5-year age bins, sex, and year from the 2007 Swaziland Demographic Health Survey (SDHS), the 2011 Swaziland HIV Incidence Measurement Survey, and the 2016 Swaziland Population Health Impact Assessment (PHIA) survey. We estimated the point prevalence of ART coverage among all HIV-infected individuals by age, sex, and year. Age-specific data on the prevalence of male circumcision from the SDHS and PHIA surveys were used as model inputs for traditional male circumcision and scale-up of voluntary medical male circumcision (VMMC). We calibrated our model using publicly available data on demographics; HIV prevalence by 5-year age bins, sex, and year; and ART coverage by age, sex, and year. We modelled the effects of five scenarios (historical scale-up of ART and VMMC [status quo], no ART or VMMC, no ART, age-targeted 90-90-90, and 100% ART initiation) to quantify the contribution of ART scale-up to declines in HIV incidence and mortality in individuals aged 15-49 by 2016, 2030, and 2050. Findings: Between 2010 and 2016, status-quo ART scale-up among adults (aged 15-49 years) in eSwatini (from 34·0% in 2010 to 74·1% in 2016) reduced HIV incidence by 43·57% (95% credible interval 39·71 to 46·36) and HIV mortality by 56·17% (54·06 to 58·92) among individuals aged 15-49 years, with larger reductions in incidence among men and mortality among women. Holding 2016 ART coverage levels by age and sex into the future, by 2030 adult HIV incidence would fall to 1·09 (0·87 to 1·29) per 100 person-years, 1·42 (1·13 to 1·71) per 100 person-years among women and 0·79 (0·63 to 0·94) per 100 person-years among men. Achieving the 90-90-90 targets evenly by age and sex would further reduce incidence beyond status-quo ART, primarily among individuals aged 15-24 years (an additional 17·37% [7·33 to 26·12] reduction between 2016 and 2030), with only modest additional incidence reductions in adults aged 35-49 years (1·99% [-5·09 to 7·74]). Achieving 100% ART initiation among all people living with HIV within an average of 6 months from infection-an upper bound of plausible treatment effect-would reduce adult HIV incidence to 0·73 infections (0·55 to 0·92) per 100 person-years by 2030 and 0·46 (0·33 to 0·59) per 100 person-years by 2050. Interpretation: Scale-up of ART over the last decade has already contributed to substantial reductions in HIV-1 incidence and mortality in eSwatini. Focused ART targeting would further reduce incidence, especially in younger individuals, but even the most aggressive treatment campaigns would be insufficient to end the epidemic in high-burden settings without a renewed focus on expanding preventive measures. Funding: Global Good Fund and the Bill & Melinda Gates Foundation.
July 2019
·
118 Reads
·
8 Citations
July 2019
·
218 Reads
·
20 Citations
July 2019
·
2 Reads
July 2019
·
6 Reads
·
1 Citation
November 2018
·
8 Reads
Data S1. Model description. Table S1. The range of PAF values by sub‐population and HIV prevalence across locations of each epidemic type (groups 1 to 5). Table S2. Proportion of sex acts using a condom by partnership type and modelled location. Table S3. The modelled states describing the natural history of HIV infection and engagement with the treatment programme. Table S4. List of parameter values used in specifying the model and their description Table S5. ART programme‐related parameter values: Those parameters which are varied under the universe of futures are highlighted. Table S6. Parameter bounds included in the model fitting. Figure S1. Demonstration of Model Fit: A scatterplot of the modelled data versus the input data for a number of variables in each location.
November 2018
·
69 Reads
·
3 Citations
Introduction Setting and monitoring progress towards targets for HIV control is critical in ensuring responsive programmes. Here, we explore how to apply targets for reduction in HIV incidence to local settings and which indicators give the strongest signal of a change in incidence in the population and are therefore most important to monitor. Methods We use location‐specific HIV transmission models, tailored to the epidemics in the counties and major cities in Kenya, to project a wide range of plausible future epidemic trajectories through varying behaviours, treatment coverage and prevention interventions. We look at the change in incidence across modelled scenarios in each location between 2015 and 2030 to inform local target setting. We also simulate the measurement of a library of potential indicators and assess which are most strongly associated with a change in incidence. Results Considerable variation was observed in the trajectory of the local epidemics under the plausible scenarios defined (only 10 of 48 locations saw a median reduction in incidence of greater than or equal to an 80% target by 2030). Indicators that provide strong signals in certain epidemic types may not perform consistently well in settings with different epidemiological features. Predicting changes in incidence is more challenging in advanced generalized epidemics compared to concentrated epidemics where changes in high‐risk sub‐populations track more closely to the population as a whole. Many indicators demonstrate only limited association with incidence (such as “condom use” or “pre‐exposure prophylaxis coverage”). This is because many other factors (low effectiveness, impact of other interventions, countervailing changes in risk behaviours, etc.) can confound the relationship between interventions and their ultimate long‐term impact, especially for an intervention with low expected coverage. The population prevalence of viral suppression shows the most consistent associations with long‐term changes in incidence even in the largest generalized epidemics. Conclusions Target setting should be appropriate for the local epidemic and what can feasibly be achieved. There is no one universally reliable indicator to predict future HIV incidence across settings. Thus, the signature of epidemic control must contain indications of success across a wide range of interventions and outcomes.
... Modelling studies from Zimbabwe suggest that distribution of self-tests to women engaged in transactional sex is an efficient strategy to avert new HIV infections and is potentially cost-effective [29]. Additional modelling suggests that secondary distribution of self-tests by female sex workers in Zimbabwe to their male partners also has the potential to be highly cost-effective at identifying HIV-positive men [30]. ...
July 2019
... This study will follow the logic of the HIV prevention cascade (the unifying framework) to measure motivation, access, and uptake of COVID-19 vaccines, as well as identify barriers to and facilitators of each step among AGYW in 14 high schools across two districts in South Africa who participated in a process and outcomes evaluation [23][24][25]. The HIV prevention cascade is a novel framework that incorporates both behavioural, social and structural theories of behaviour change, providing a comprehensive model of the steps required to take up a disease prevention method [26]. ...
June 2020
... In [6], the authors explored the challenges in estimating HIV prevalence trends and geographical variation in HIV prevalence with novel statistical observations. Some novel statistics on the remarkable impact of long-acting cabotegravir for HIV prevention in South Africa have been explored in ref. [7]. The authors in [8] proposed a nonlinear model of HIV considering the impact of stochastic environmental fluctuations. ...
June 2020
The Journal of Infectious Diseases
... A patient with an undetectable VL has preserved immune system function, increased length and quality of life, and reduced contagiousness. In turn, the level of HIV spread in the population decreases [2][3][4]. In recent years, ART for HIV has become more accessible and effective, reducing the number of HIV deaths worldwide. ...
February 2020
The Lancet HIV
... Goal setting recognizes AGYW's self-autonomy, which can facilitate open communication with providers, including identifying barriers such as depression experienced by AGYW [35]. To build trust, PrEP providers must treat AGYW nonjudgmentally for their choices, including PrEP use and sexual behavior [21,54]. A greater understanding of trust factors is essential to create effective tools that improve patient-provider interactions. ...
July 2019
... Consumer segmentation is a widely used technique within marketing to align the demand and supply of services to groups of individuals with shared priorities and needs based on their behaviour, attitudes and beliefs [18][19][20]. Market segmentation has previously been used in family planning counselling and for HIV prevention through voluntary medical male circumcision [21][22][23]. The POWER (Prevention Options for Women Evaluation Research) study provided PrEP to AGYW in Cape Town, South Africa, via differentiated PrEP delivery models, which included initiation at a mobile clinic or government health facility, with follow-up and PrEP refills offered at four platforms, including the mobile clinic, government health facility, as well as via a youth PrEP club, and courier delivery. ...
July 2019
... Local epidemiological data of HIV positive individuals provides insight into the high-risk behaviour (HRB) and the common routes of transmission present in the society, thus are critical in identifying the target group and in ensuring safe practices amongst the target group. 6 There is hardly any literature available on epidemiological data of HIV positive individuals in and around Lucknow and Uttar Pradesh as a whole. ...
November 2018
... Indirect estimates suggest, however, that mortality remained fairly stable over time. For Zimbabwe, this is not plausible as mortality declined owing to the roll-out of antiretroviral therapy during this period [32]. This decline is not well reflected here, most likely due to the assumption of linearity of trends required to date the estimates. ...
October 2017
BMJ Open
... The worldwide prevalence rate for persons aged 15-49 worldwide is 13.2%. 22 People infected with this virus get genital herpes, and neonatal herpes acquired during parturition from genital herpes is an extremely high threat to newborns. 23 However, HSV-2 vaccination is still not readily available. ...
October 2008
Bulletin of the World Health Organization
... All birth history estimates of fertility and mortality rest on the assumptions that reporting on live and dead children is similarly accurate, that dates of birth and ages at death are reasonably accurately reported, and that there is no correlation between the mortality risk of a child and the survival of mother. Bias in estimates also arise when dead mothers had different fertility than surviving mothers [22,23]. Several studies have been conducted on the quality of birth histories in DHS and we build on this work for examining TBH surveys [8,24,17]. ...
October 2010
Bulletin of the World Health Organization