The herpes simplex virus, or herpes, is categorized into 2 types: herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). HSV-1 is mainly transmitted by oral-to-oral contact to cause oral herpes (which can include symptoms known as “cold sores”), but can also cause genital herpes (through mouth to genital contact or vice versa).

HSV-2 is a sexually transmitted infection that causes genital herpes. Both HSV-1 and HSV-2 infections are life-long. An estimated 417 million people aged 15-49 (11%) worldwide have HSV-2 infection. Symptoms of herpes include painful blisters or ulcers at the site of infection. Herpes infections are most contagious when symptoms are present but can still be transmitted to others in the absence of symptoms.