Gus, originally from London, has been living with HIV for the past 40 years. He received a formal AIDS diagnosis in 1990 when his doctor informed him that his CD4 count had dropped below 200, thus classifying him as having AIDS.

Gus Cairns trained as a psychotherapist and practised from 1998 to 2016. Throughout his career, he encountered many remarkable clients and fellow therapists who provided valuable insights into various personal and professional issues. However, in 2016, Gus chose to focus solely on HIV activism, feeling that he could not fully commit to both his therapy practice and his activism.

In late 1997, Gus volunteered with the UK Coalition for People Living with HIV and AIDS. The following year, he was appointed Assistant Editor of Positive Nation, the UK’s magazine for people living with HIV, and became the editor in 1999. He left his editorial position in 2002, although he continued to serve as a board member for some time. From 2002 to 2008, Gus worked as a freelance writer and activist. In 2008, he became the editor of HIV Treatment Update. With the cessation of HTU’s publication in 2013, Gus remained with NAM as a staff editor until June 2022, when he retired. He freelances for Aidsmap and other organisations, including EATG and EACS.

In 2016, Gus, in collaboration with Bruce Richman, coined the term U=U (Undetectable equals Untransmittable) while brainstorming outside the CROI conference in Boston. This campaign aimed to raise awareness about the non-infectious status of individuals with an undetectable viral load.

Gus has advocated for PrEP since the early 2000s and organised two successful summits for activists and providers in Amsterdam in 2018 and Warsaw in 2019. A third summit was planned for Kyiv but was postponed due to COVID-19. Gus considers these meetings, which he organised almost single-handedly and without pharmaceutical funding, his proudest professional achievements.