Sir Keir Starmer has become the first sitting UK prime minister to publicly take an HIV test to reduce stigma around Aids and encourage more people to get tested.
There are historical parallels. In 1956, when Elvis Presley, at the height of his fame, was photographed receiving the polio vaccine at CBS Studio 50.
Do these high-profile gestures really change attitudes and behaviour, or are they just headline-grabbing stunts?
