About 175 million Americans are latently infected with herpes virus type 1 (HSV-1), and ~55 million are latently infected with herpes virus type 2 (HSV-2).
5% of infected people experience frequent, recurrent outbreaks, this translates into roughly 10 million Americans who get recurrent cold sores and 3 million who experience 1 to 4 outbreaks of genital herpes each year. Furthermore, having herpes greatly increases the risk of acquiring HIV.
An effective live-attenuated vaccine could mean an end to the herpes epidemic, as shown by the success of the chickenpox vaccine.