This is from a most-likely biased
source but if true it's interesting:
USAID refuses to release report that shows abstinence works in HIV prevention
Washington DC, Feb. 15, 2005 (CNA) - The U.S. Agency for International Development (USAID) has shelved a study that highlights the effectiveness of abstinence education in reducing HIV infection and has commissioned a second study to a researcher known to advocate condom distribution instead.
Focus on the Family has urged key members of Congress to look into why a government health agency, charged with dispersing funds to HIV-prevention efforts in Africa, is contradicting Bush administration policy that supports abstinence education.
The issue is examined in depth in the March issue of Focus on the Family’s Citizen Magazine, which has been mailed to hundreds of senators and congressmen. The cover story, titled "Burying the Truth," examines the research being suppressed, which was conducted by Harvard scientist Edward C. Green, a self-described "secular liberal."