Genital herpes is one of the most common sexually transmitted infections in the world. Globally, an estimated 520 million people aged 15 to 49 have HSV-2, the primary cause of genital herpes. In the United States, roughly 1 in 8 people in that same age range carry the virus. Despite how widespread it is, up to 90% of people with genital herpes don’t know they have it, which is a major reason it continues to spread.
Prevalence in the United States
Among Americans aged 14 to 49, HSV-2 prevalence sits at about 12%. That number climbs steadily with age. Less than 1% of teenagers aged 14 to 19 test positive, but by the time people reach their 40s, more than 1 in 5 (21.2%) carry the virus. The jump from one age bracket to the next is significant: 7.6% among 20- to 29-year-olds, 13.3% among 30- to 39-year-olds, and 21.2% among 40- to 49-year-olds.
These numbers only capture HSV-2. A growing share of new genital herpes cases are now caused by HSV-1, the strain traditionally associated with cold sores. When you account for both virus types, the true number of people living with genital herpes is considerably higher than the 12% figure suggests.
Who Is Most Affected
Women are nearly twice as likely as men to have HSV-2. The age-adjusted prevalence among women is 15.9%, compared to 8.2% among men. This gap exists because the virus transmits more efficiently from men to women during sex, a pattern the World Health Organization has documented globally.
Racial disparities in the U.S. are stark. Among non-Hispanic Black Americans, HSV-2 prevalence is 34.6%, roughly four times higher than among non-Hispanic white Americans (8.1%) or Mexican Americans (9.4%). Non-Hispanic Asian Americans have the lowest recorded prevalence at 3.8%. These differences reflect disparities in healthcare access, sexual network patterns, and socioeconomic factors rather than any biological susceptibility.
HSV-1 Is Changing the Picture
Genital herpes caused by HSV-1 is rising quickly, especially among young people. A large U.S. study tracking over 40,000 students aged 16 to 21 found that HSV-1 accounted for 78% of all genital herpes isolates by 2001, up from just 31% in 1993. That trend has continued. A 2023 meta-analysis calculated that HSV-1 now accounts for about 37% of all genital herpes cases worldwide, with the proportion increasing by roughly 4% per year.
The shift is partly driven by declining rates of oral HSV-1 infection in childhood. In previous generations, most people caught HSV-1 on the mouth as kids, which gave them some degree of immune protection against genital HSV-1 later in life. Fewer childhood infections mean more young adults encounter the virus for the first time through oral sex, resulting in a genital infection instead.
Why Most People Don’t Know They Have It
The vast majority of people with genital herpes, an estimated 90%, are unaware they carry the virus. Some never develop noticeable symptoms. Others have mild or infrequent outbreaks they mistake for ingrown hairs, yeast infections, or skin irritation. Standard STI panels typically do not include herpes blood tests unless you specifically request one, so many infections go undetected even in people who get tested regularly.
Even without symptoms, the virus can still be transmitted. During the first six months after infection, the virus is present on the skin’s surface (a process called viral shedding) on 20% to 40% of days. Over time, shedding becomes less frequent but doesn’t stop. People with longer-term infections shed the virus on roughly 5% to 20% of days, with no visible sores present. This invisible shedding is a major driver of transmission, since people are most likely to pass the virus when they don’t realize they’re contagious.
Global Numbers
Worldwide, the WHO estimates that 13% of people aged 15 to 49 have HSV-2. That translates to roughly 520 million people. In 2020, about 205 million of those experienced at least one symptomatic episode, meaning most people with the infection go through any given year without a recognized outbreak. The highest number of new infections occurs among adolescents and young adults, even though overall prevalence is highest in older age groups (because the virus stays in the body for life and accumulates across populations over time).
What the Numbers Mean in Context
Genital herpes is far more common than most people assume. If you’re in a room with eight American adults, statistically one of them has HSV-2, and most of the eight wouldn’t know their own status with certainty. The stigma around herpes tends to be disproportionate to its medical impact. For the majority of people, the infection causes mild or infrequent symptoms and poses no serious health risks. The exceptions are pregnancy, where an active outbreak during delivery can be dangerous for the newborn, and people with weakened immune systems, who may experience more severe or frequent episodes.
Because so many people carry the virus without symptoms, and because standard testing doesn’t routinely screen for it, the gap between actual prevalence and perceived prevalence remains wide. The infection is, by any measure, extremely common.