Prince Harry says he believes the UK has "turned a corner" in relation to HIV stigma just days ahead of a national testing week for the illness.
The royal threw his weight behind HIV Testing Week as he visited a pop-up clinic in Homerton to encourage people to check their status.
Harry handed out self-test kits on Wednesday which can establish in just 15 minutes whether somebody is HIV positive.
As he watched the face of the "Give the finger to HIV" campaign, Harry said people could no longer be demonised for getting tested and are only "irresponsible" if they do not know their status.
The self-use kit involves a simple finger-prick test, Harry was told.
Encouraging people to get tested, Harry said: "If you are positive, it's absolutely fine - you can have a healthy, happy life.
"Rather than not knowing your status and being on medication for a period of your life, or the rest of your life, rather than letting yourself get to that point where there is no return, I must stress to everyone how important it is (to get tested).
"The sooner the better."
Harry's visit comes 30 years since his mother Princess Diana was first credited for challenging the stigma against those afflicted by the virus.
At the opening of the UK's first purpose-built HIV/Aids unit that cared exclusively for those suffering with the disease, the 25-year-old Princess shook hands with an Aids patient without wearing gloves - dispelling myths that it could be passed from person to person by touch.
HIV Testing Week begins on 18 November.