About the Project
Global efforts to eliminate AIDS have failed key populations. This includes transgender people who have 19-times higher risk of acquiring HIV than other adults globally[1], and a global HIV prevalence of 19.9%[6]. Transgender people face substantial stigma,[2,3] and in many countries, can be subjected to arrest and face considerable homelessness and poverty[2,4]; termed structural factors. Studies suggest that the risk of HIV transmission may be higher among transgender people that have experienced higher exposure of structural factors[3,7,8]. Uptake of interventions can also be lower in transgender people[1,4], with evidence suggesting that structural factors reduce the uptake of HIV testing, as well as outcomes for HIV pre-exposure prophylaxis and HIV treatment,[1,9-11] and access to healthcare[1].

Despite this potential role of structural factors, there is little understanding of the contribution that structural factors make to the heightened HIV risk experienced by transgender people. Mathematical modelling, which has been rarely used for this population, can evaluate this and so produce insights for guiding intervention development to reduce the disproportionate HIV risk among transgender people. This is a key target of the 2021 UN declaration to eliminate AIDS by 2030[5], which includes a focus on key populations and reducing the effect of structural factors.

Aims and objectives
We hypothesise that structural factors heighten the HIV-risk among transgender women, and that interventions to mitigate their effects are essential for achieving HIV elimination. To evidence this hypothesis, the following aims are planned:

1. Undertake a systematic review of epidemiological studies among transgender women to undertake meta-analyses of the effect of structural factors on HIV incidence/prevalence.
2. Use country-specific datasets to evaluate the effect of structural factors on HIV-related outcomes among transgender women, using causal methods.
3. Use infectious disease modelling to evaluate the contribution of structural factors to HIV transmission among transgender women, and the impact of related interventions.

Methodology
A systematic review of HIV prevalence and incidence studies among transgender women will be undertaken. Estimates will be extracted of the association between HIV incidence/prevalence and exposure to different structural factors. Study authors will be asked to provide estimates if they are not available and meta-analyses will synthesise estimates for each structural factor.

Utilising existing datasets of transgender women collected by Dr Wilson’s team, epidemiological analyses will assess how exposure to structural factors affect HIV risk behaviours and access to and outcomes of HIV prevention/treatment interventions. We will use causal mediation analysis and utilise longitudinal datasets where possible. Possible settings include USA, Nepal and Brazil.

A HIV transmission model for transgender women will be developed for settings from aim 2, with the model including structural factors of importance for that setting. The model will evaluate the contribution of specific structural factors to HIV transmission in that setting, and assess the impact of possible intervention scenarios; based on literature and through discussion with our team and the transgender community.

The student will develop skills in: 1) systematic reviews and meta-analyses; 2) epidemiological analyses, including causal mediation analysis; 3) infectious disease modelling; and 4) collaborating with multi-disciplinary teams to undertake policy-relevant modelling.

Supervisors: Dr Hannah Fraser (primary supervisor), Prof. Peter Vickerman, Dr Erin Wilson (UCSF), Dr Josephine Walker (UoB)

Funding available
This project is open for Bristol PGR scholarship applications (closing date 1st December 2023; https://www.bristol.ac.uk/health-sciences/courses/postgraduate/phd-studentships/)

The Bristol PGR scholarship funds tuition fees, the costs of carrying out your research and a maintenance stipend (at the minimum UKRI rate) for the duration of a PhD (four years).

How to apply for this project
This project will be based in Bristol Medical School - Population Health Sciences in the Faculty of Health Sciences at the University of Bristol. Use this information to search for the relevant programme in our online application system.

Please visit the Faculty of Health Sciences website for details of how to apply, the information you must include in your application, and for information about our online Application Workshop to help you submit a competitive application.

References

1. UNAIDS. (https://www.unaids.org/en/resources/documents/2021/04-hiv-human-rights-factsheet-transgender-gender-diverse)
2. US CDC (http://www.cdc.gov/hiv/library/reports/hiv-surveillance.html)
3. Poteat T, PLoS Med. 2017;14(11):e1002422. DOI: 10.1371/journal.pmed.1002422
4. Wilson EC, JIAS. 2020;23 Suppl 3(Suppl 3):e25539. DOI: 10.1002/jia2.25539
5. UN General Assembly. Political Declaration on HIV and AIDS: Ending Inequalities and Getting on Track to End AIDS by 2030.
6. Stutterheim SE, PLoS One. 2021;16(12):e0260063. DOI: 10.1371/journal.pone.0260063
7. McFarland W, JAIDS 2020;84(1):e7-e10. DOI: 10.1097/QAI.0000000000002315
8. Raiford JL, AIDS Behav. 2016;20(10):2212-2221. DOI: 10.1007/s10461-016-1424-8
9. Lee K, MMWR 2022;71(20):673-679. DOI: 10.15585/mmwr.mm7120a1
10. Santos GM, STI 2014;90(5):430-433. DOI: 10.1111/dar.12116
11. Wilson EC, AIDS Care. 2018;30(11):1356-1359. DOI: 10.1080/09540121.2018.1489102