Trials have shown that rates of HIV infection are reduced if people not infected with HIV take anti-retrovirals - known as pre-exposure prophylaxis (PrEP). But adherence to a daily dose is a problem.
Young women in southern Africa are most at risk of becoming infected with HIV. If they take a pre-exposure prophylaxis like Truvada it could change their lives.
Professor of medicine and deputy director of the Desmond Tutu HIV Centre at the Institute of Infectious Disease and Molecular Medicine, University of Cape Town