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Homelessness and unstable housing are associated with increased HIV and HCV risk among people who inject drugs

26 March 2021 

Homelessness and unstable housing are associated with a substantial increase in HIV and hepatitis C virus (HCV) acquisition risk among people who inject drugs, according to research led by the NIHR Health Protection Research Unit in Behavioural Science and Evaluation at the University of Bristol

Homeless person sitting with head in arms against the wall of an underpass

The study, published in The Lancet Public Health today [26 March] found that, among people who inject drugs, recent homelessness and unstable housing were associated with a 55 per cent and 65 per cent increase in HIV and HCV acquisition risk, respectively. 

The study is the first systematic review and meta-analysis (a statistical method used to combine the results of multiple studies) to assess whether homelessness or unstable housing increases HIV or HCV risk among people who inject drugs. The researchers extracted and pooled data from 45 previous studies providing 70 estimates (26 for HIV and 44 for HCV) to work out a more robust measure of the risks. 

Globally, there are an estimated 15.6 million people who inject drugs; over one in six are infected with HIV and over half have been infected with HCV. People who inject drugs are at high risk of HIV and HCV infection through the sharing of needles, syringes and other injecting equipment and experience high levels of homelessness and unstable housing. 

Globally, an estimated 22 per cent of people who inject drugs reported experiencing homelessness or unstable housing in the past year, with this increasing to 42 per cent in England (having increased from 28 per cent in the last decade), and 50 per cent in North America.

A high proportion of people in unstable housing have substance misuse problems, with 30% reporting they used heroin in the last month in the UK, highlighting the overlapping risks of drug use and homelessness.

Previous research also suggests that homeless or unstably housed drug users are less likely to access HIV and HCV treatment and use opioid substitution therapy and needle-syringe programmes, two important HIV and HCV prevention interventions. They may also be more likely to engage in high-risk injecting and sexual behaviours and more likely to have been recently imprisoned, another factor associated with increased HIV and HCV acquisition risk. 

Chiedozie Arum, lead author from the University of Bristol, said: “Our study highlights the overlapping bio-social problems that worsen health inequalities among homeless people who inject drugs. Expanding access to prevention and treatment services and improving housing provision for this population should be prioritised.” 

Dr Jack Stone, Senior Research Associate from the University of Bristol and joint senior author, said: “Our findings suggest housing instability is an important driver of HIV and HCV transmission among people who inject drugs. Further research is now needed to better understand how homelessness or unstable housing increases the risk of HIV and HCV acquisition, and what interventions could have most impact in reducing this risk.”  

Peter Vickerman, Professor of Infectious Disease Modelling from the University of Bristol and joint senior author, said “This research adds to the growing evidence on the damaging effect of housing instability on health and social outcomes. A comprehensive policy approach that not only provides housing but also addresses many of the interlinked health and social concerns of this population is necessary in order to reduce HIV and HCV risk”.

The study has important implications for policy and public health, including:

  • the need for housing interventions tailored to people who inject drugs that address their competing health and social concerns
  • the need for improved access to HIV and HCV prevention and treatment interventions among those who are homeless or unstably housed
  • the need for these interventions to be integrated within services that provide for the wide ranging health needs of these vulnerable populations
  • the need to reduce stigma towards homelessness and drug use that act as barriers to accessing care.

The authors note that, in response to the ongoing COVID-19 pandemic, many countries rapidly escalated their efforts to provide safe and secure housing to homeless or unstably housed individuals, showing that dramatic, if only temporary, changes are possible if there is the political will. This paper supports the need to continue these initiatives after the COVID-19 pandemic.

The research was funded by the National Institute for Health Research (NIHR), Commonwealth Scholarship Commission, and the US National Institutes of Health.

Paper: Homelessness, unstable housing and risk of HIV and hepatitis C virus acquisition among people who inject drugs – a systematic review and meta-analysis by Chiedozie Arum et al. Published in The Lancet Public Health. [26 March 2021]


About the NIHR Health Protection Research Unit [HPRU] in Behavioural Science and Evaluation at the University of Bristol 

The NIHR HPRU in Behavioural Science and Evaluation at University of Bristol is one of 14 HPRUs across England, part of a £58.7 million investment by the NIHR to protect the health of the nation. 

The NIHR HPRU in Behavioural Science and Evaluation is a partnership between Public Health England and University of Bristol, in collaboration with MRC Biostatistics Research Unit at the University of Cambridge and University of the West of England. 

Each NIHR HPRU undertakes high quality research that is used by PHE to keep the public safe from current and emerging public health threats.

About the NIHR 

The National Institute for Health Research (NIHR) is the nation's largest funder of health and care research. The NIHR:

  • funds, supports and delivers high quality research that benefits the NHS, public health and social care
  • engages and involves patients, carers and the public in order to improve the reach, quality and impact of research
  • attracts, trains and supports the best researchers to tackle the complex health and care challenges of the future
  • invests in world-class infrastructure and a skilled delivery workforce to translate discoveries into improved treatments and services
  • partners with other public funders, charities and industry to maximise the value of research to patients and the economy.

The NIHR was established in 2006 to improve the health and wealth of the nation through research, and is funded by the Department of Health and Social Care. In addition to its national role, the NIHR supports applied health research for the direct and primary benefit of people in low- and middle-income countries, using UK aid from the UK government.