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.
Three new studies conducted in South Africa provide insights into the engine that drives HIV transmission in the country.
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.