A mathematical modeling study published in Sexually Transmitted Infections estimated that nearly 4 billion people worldwide had herpes simplex virus (HSV) infections in 2020. Of these, 520 million had HSV-2 infections, and 376 million experienced genital HSV-1. New infections among those aged 15 to 49 totaled 26 million for HSV-2 and 17 million for genital HSV-1.
HSV-1, traditionally an oral infection acquired in childhood, was increasingly transmitted genitally among adolescents and adults in high-income regions. In contrast, HSV-2 remained predominantly sexually transmitted. The African region exhibited the highest HSV-2 prevalence (17.0% in females; 9.7% in males), while genital HSV-1 incidence peaked in the Western Pacific.
Approximately 204.6 million individuals experienced genital ulcer disease (GUD) attributable to HSV in 2020. HSV-related complications included an elevated risk of HIV acquisition and neonatal herpes, a severe condition with high mortality.
The study highlighted data gaps, particularly for HSV-1 prevalence in children, and noted the limited efficacy of existing prevention methods. Researchers advocated for vaccines as a critical step toward reducing HSV's global burden.
The study authors declared no competing interests except for one of the joint senior authors, who reported grants from WHO during the conduct of the study and outside the submitted work, as well as a grant from GSK outside the submitted work.