People who inject drugs have high rates of HIV and hepatitis C virus (HCV) infection. They also experience high rates of homelessness, with evidence suggesting that homelessness increases their risk of HIV and HCV infection and reduces their access to health services. Epidemiological analyses and infectious disease modelling will be used to evaluate the contribution of homelessness to HIV and HCV epidemics among people who inject drugs and evaluate strategies to reduce this risk.

The World Health Organisation (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) have set targets for eliminating hepatitis C virus (HCV) and HIV. To achieve these goals, multiple studies have shown the importance of scaling-up prevention and treatment efforts among people who inject drugs because of their high burden of HIV and HCV. Few studies, however, have examined whether these efforts should address broader social determinants and structural factors affecting people who inject drugs.

Due to the criminalisation of drug use and its social exclusion, people who inject drugs commonly experience incarceration (58% ever) and homelessness (22% past year). We have shown that both these factors are associated with substantial HIV and HCV transmission risk, with incarceration possibly contributing to over half of new HCV/HCV infections in some settings and homelessness also contributing considerably to the global HCV/HCV infections. Homelessness has also been shown to be associated with poor prevention and treatment outcomes, heightened injecting and sexual risk behaviour, increased physical and sexual violence, food insecurity, increased mortality and poor access to health services. Housing interventions have been shown to mitigate some of these effects. Despite the considerable negative effects of homelessness, only one modelling analysis has examined the role of homelessness in driving HCV or HIV transmission among people who inject drugs.

This PhD project will use infectious disease modelling and epidemiological analyses to evaluate the degree to which homeless targeted and housing-oriented interventions could reduce the HIV and HCV epidemics among people who inject drugs. We propose the following:

1. Through existing and new systematic review, evaluate the effect of homelessness on HIV and HCV behavioural, prevention and treatment outcomes among people who inject drugs, and possible impact of interventions for mitigating these effects
2. For selected global settings, undertake epidemiological analyses and modelling to estimate the contribution of homelessness to HIV and HCV transmission among people who inject drugs, incorporating the effect on multiple health outcomes.
3. Evaluate the potential impact of homeless targeted or housing-oriented interventions on reducing this risk in these settings.

The student will join a vibrant and diverse multi-disciplinary research team. Through existing collaborators, the student will undertake policy relevant modelling in selected sites in Europe/USA, Africa and/or Asia, with there being opportunities to visit their chosen study sites. Collaborators with expertise in homelessness research (Peter McKie from University of Cardiff) will guide the modelling and interventions considered, and will ensure the modelling is policy relevant and influential. The PhD is likely to result in high impact publications, with potential to influence public health policy through presentations at international conferences and meetings with WHO, UNAIDS, the Institute of Global Homelessness and other agencies.

This project would suit a PhD candidate with a strong numerical background, although they may have varied skills depending on their previous qualifications and training. Depending on the skills, the student will receive training in statistics and epidemiology, coding, systematic reviews and meta-analysis, and infectious disease modelling. In the first few weeks the supervisory team will undertake an assessment of the candidate’s training needs to learn which areas the student is strong in, and which areas would be a priority for strengthening. Training will be through the supervisory team as well as through taking relevant short courses at the University of Bristol (http://www.bristol.ac.uk/medical-school/study/short-courses/). There is flexibility in refining the project, including the amount of modelling that is undertaken, which countries to model, health harms to consider (HIV and/or HCV transmission and other health outcomes), datasets that are analysed, and whether to include an economic or systematic review component.

Funding Notes
This project is only available for UK-domiciled, home fee applicants of Black African, Black Caribbean or other Black or mixed Black heritage. The studentship duration is four years, and it includes an annual stipend set at the current UKRI recommendation of £20,780 (for 25/26, updated annually). Tuition fees and research costs are fully supported by the studentship, as well as an allowance for paid sick leave and parental leave, in addition to 5 weeks of paid leave each year.