Taking six shots a year, as opposed to 365 pills, yielded huge advantages among women in a recent trial.
Nations that don't penalize same-sex activity have lower rates of HIV among men who have sex with men.
The finding is further proof HIV crossed over to humans decades before it turned into a pandemic.
The two international organizations say service disruptions could cause massive suffering.
Attacked by a mob, gay, HIV activist Edafe Okporo fled Nigeria. Listen as he talks about being gay in a country where it is illegal and HIV stigma is huge.
This early ancestor is to blame for passing the bothersome virus onto modern humans.
The U.S. is spending millions of dollars to develop a vaginal ring designed to help prevent HIV.