A diagnosis of HIV used to be a death sentence, but thanks to advances in science it’s now treatable, if not curable. Even so, 35 million people have died of HIV-related diseases.

Dr Chris van Tulleken’s look at the fight against the disease sees him travelling to South Africa, where the outlook for someone with HIV is far from rosy, to meet medics at the front line, while Elton John discusses the continuing stigma against gay men.