HIV/AIDS has claimed around 35 million lives worldwide. But now, as Dr Chris van Tulleken reveals, cutting-edge science can keep the virus at bay or even prevent infection altogether. As a new preventative treatment called PrEP is rolled out on the NHS in Scotland, and new trials are announced in England and Wales, HIV is under control, in Britain at least, but only when it can be detected and the treatment with antiretroviral drugs (ARVs) can begin.