The impact of homelessness and housing insecurity on HIV.

Homelessness is a global problem with wide-ranging causes and contexts. People experiencing homelessness and unstable housing (HUH) are disproportionately affected by HIV and face worse treatment outcomes than those with stable housing due to multiple complex barriers to care. Even in settings with universal health coverage, access to HIV prevention and treatment services remains insufficient for people experiencing HUH. Health system barriers-such as difficult-to-navigate, fragmented care systems and the mistreatment faced in health-care settings-hinder the engagement of this population in HIV care. Tailored service delivery models, including low-barrier care, mobile and street-based care, and long-acting antiretroviral medications for prevention and treatment, show promise in addressing these barriers and improving HIV outcomes among people experiencing HUH. Future research should prioritise high-quality studies of differentiated service delivery, implementation science to optimise prevention and care programmes for this population in varied settings, and expanded access to long-acting pre-exposure prophylaxis and antiretroviral therapy, particularly in low-income and middle-income countries.