Clíona Ní Cheallaigh is an Infectious Diseases and Internal Medicine Physician in St James’s Hospital and Senior Lecturer in Medical Gerontology in Trinity College, Dublin. Her clinical and research interests centre around the health of multiply excluded individuals: homeless people, injecting drug users and other marginalised groups. She has established an Inclusion Medicine service within St James’s Hospital to provide integrated, active case management-based care to these individuals in the hospital and in outreach clinics to addiction services. Her research seeks to look at the effect of the extreme psycho-social stress experienced by multiply excluded individuals on three levels: the cellular/immune activating consequences of this stress; the effect of this stress on health, particularly frailty and brain health; and finally on health services adaptation to meet the needs of this population.