According to the UNAIDS 2012 report,
globally, 34 million people were
living with HIV at the end of 2011.
HIV/AIDS is a major cause of death,
having killed about 1.7 million people
in that same year. The number of
new infections was even higher (2.5
million), suggesting an even more
severe problem in the future. Sexual
HIV transmission accounts for the
overwhelming majority of the newly
infected. The United Nations named
combatting HIV/AIDS one of its eight
Millennium Development Goals. The
natural question is then: what are the
effective policies? Prevention policies
have been argued to be more costeffective
than treatment1
. The obvious
next question is: Which prevention
policies have a greater impact?