According to the Center for Disease Control and Prevention (CDC), about 48% of the US population aged 14-49 is infected with HSV-1 and about 12% of the US population aged 14-49 is infected with HSV-2..
Worldwide (in 2012) nearly one half billion people were infected with HSV-2 between the ages of 15 and 49—and the number rises with age and the number of life partners. More women than men have herpes (14.8% versus 8% global prevalence, respectively). In the US, the number of people infected has been dropping, but the news isn’t all good. The percentage of people with a positive blood test for HSV-2 has declined. In people age 14 to 49, 21% were positive in the early 90s. By 2010, that number dropped to about 16%. Unfortunately, the improvement has been seen mostly in the white population “with stable rates in black populations, resulting in worsening racial disparities such that for every one white man, four black men are infected, with similar ratios for women.”
The reasons for this might be that access to information, education—and the medication that can reduce the risk of transmission—has not been made available to all equally.
In the United States, the prevalence of HSV-1, which accounts for the vast majority of oral herpes, has dropped 29% among 14–19 year olds, from approximately 42% to 30%, over the past 30 years. As a result, adolescents and young adults may experience their first exposure to HSV-1 with the initiation of sexual activity, including oral sex.