Among MSM*, the estimated number of new HIV infections increased overall and among MSM aged 13–24. MSM remain the population most heavily affected by HIV infection. Comparing 2008 to 2010, the number of new HIV infections among MSM increased 12% from 26,700 in 2008 to 29,800 in 2010, with a 22% increase among MSM aged 13–24 from 7,200 in 2008 to 8,800 in 2010. Although MSM represent about 4% of the male population in the United States, in 2010 MSM accounted for 78% of the new HIV infections among males.
*MSM = Men who have sex with men.