Most 17- to 19-year-olds are sexually active, and 30 percent of 15- and 16-year-olds have had sex, according to a study published last month by the journal Pediatrics.

NPR: Justice Department Appeals Morning-After Case

The two-and-a-half-year-old CAPRISA trial followed nearly 900 HIV-negative, sexually active South African women between ages 18 and 40 to determine how safe and effective tenofovir gel was in preventing HIV infection.

CNN: Gel cuts HIV transmission rate in study

The upshot, according to Brian Williams of the World Health Organisation, is that if, in some ideal world, every sexually active man in sub-Saharan Africa were circumcised, 2m new infections would be avoided over the course of ten years, and 300, 000 deaths prevented.

ECONOMIST: The XVIIth International AIDS Conference