Herpes simplex virus (HSV) spreads primarily through direct skin-to-skin contact with an infected person. The virus can transmit even when no sores are visible, which is why herpes is so common: over 846 million people aged 15 to 49 are living with genital herpes infections worldwide, according to WHO estimates from 2020. Understanding exactly how and when the virus passes between people can help you assess your own risk realistically.
HSV-1 vs. HSV-2: Different Routes of Spread
The two types of herpes simplex spread through different kinds of contact, though there is overlap. HSV-1 transmits mainly through contact with sores, saliva, or skin in and around the mouth. Kissing is the most common route. Less commonly, HSV-1 reaches the genital area through oral sex, where it causes genital herpes. About 376 million people had genital HSV-1 infections in 2020, making oral-to-genital transmission far from rare.
HSV-2 spreads mainly during vaginal, anal, or genital-to-genital sexual contact. It passes through skin, mucous membranes, sores, and genital fluids. Unlike HSV-1, which most people pick up during childhood, HSV-2 is acquired almost entirely through sexual activity. Around 520 million people worldwide have genital HSV-2.
Transmission Without Visible Symptoms
One of the most important things to know about herpes is that it frequently spreads when the infected person has no symptoms at all. The virus periodically reactivates and travels to the skin surface in a process called viral shedding. During shedding, the virus is present on the skin or mucous membranes in amounts large enough to infect a partner, yet the person shedding feels nothing and sees nothing unusual.
Research from the University of Washington tracked people with new genital HSV-1 infections and found that at two months after infection, participants shed virus on about 12% of days. By 11 months, that dropped to 7% of days. Among those who shed most frequently, the rate fell further to just 1.3% of days by two years out. In most instances, participants had no symptoms during shedding episodes. HSV-2 is generally associated with more frequent shedding and recurrences than genital HSV-1, which is one reason HSV-2 accounts for the majority of genital herpes transmission.
The greatest risk of passing herpes to someone else is during an active outbreak, when sores are present. But because asymptomatic shedding is so common, a large share of new infections come from partners who didn’t know they were contagious at the time.
Actual Transmission Rates Between Partners
If you’re in a relationship where one partner has genital HSV-2 and the other doesn’t, the numbers are more modest than many people expect. In a large study of nearly 1,500 monogamous heterosexual couples, 3.6% of susceptible partners acquired HSV-2 over an eight-month period when no preventive medication was used. That translates to roughly a 5% annual risk without any precautions beyond avoiding sex during outbreaks.
Gender and prior immunity both matter. In an earlier study of 144 couples, the annual acquisition rate for women whose male partner was the source was significantly higher than for men whose female partner was the source (about 17% vs. 4%). Women who already had HSV-1 antibodies had a lower risk of acquiring HSV-2 (about 9% annually) compared to women with no prior herpes antibodies of either type (about 32% annually). Existing HSV-1 immunity appears to offer partial, though incomplete, protection against HSV-2.
How Condoms and Antivirals Reduce Risk
Condoms lower the risk of transmission, but not equally for both sexes. A study analyzing condom use found that women who used condoms for more than 25% of sex acts had roughly a 90% reduction in their risk of acquiring HSV-2. For men, however, condoms did not show a statistically significant protective effect. The likely explanation is anatomical: condoms cover the primary site of male viral shedding (the penile shaft) but leave exposed the broader genital skin area where men can acquire the virus.
Daily suppressive antiviral medication taken by the infected partner cuts the transmission rate roughly in half. In the large couples study mentioned above, the acquisition rate dropped from 3.6% to 1.9% over eight months when the infected partner took daily antivirals. Combining suppressive therapy with condom use offers the greatest reduction in risk, though neither method eliminates the possibility entirely.
Can You Get Herpes From Objects or Surfaces?
HSV can survive on dry surfaces for anywhere from a few hours to several weeks, with longer survival in low-humidity environments. That said, direct skin-to-skin or skin-to-mucous-membrane contact is overwhelmingly the way herpes spreads. Transmission through shared towels, drinking glasses, or toilet seats is theoretically possible but not considered a meaningful route of infection. The virus is fragile outside the body in real-world conditions, and the amount of virus on a surface drops quickly. Public health agencies consistently identify direct contact with infected skin or secretions as the primary mode of transmission.
Timeline From Exposure to First Symptoms
If you’re exposed to HSV and become infected, the first symptoms typically appear 6 to 8 days later, though the incubation period can range from 1 to 26 days. A first outbreak is usually the most severe, with painful blisters or ulcers at the site of infection, sometimes accompanied by flu-like symptoms such as fever and swollen lymph nodes. Some people, however, never develop noticeable symptoms after their initial infection and only discover they carry the virus through a blood test or when they unknowingly transmit it to a partner.
Transmission During Pregnancy and Birth
Herpes can pass from mother to baby, and about 85% of neonatal herpes cases result from exposure during delivery rather than during pregnancy itself. The risk is highest when a mother acquires a new genital herpes infection late in pregnancy, because her body hasn’t yet built up antibodies that would help protect the baby, and the virus is more likely to be actively present in the genital tract at the time of delivery. Women with a long-standing herpes infection before pregnancy have a much lower risk of transmitting to their newborn, because maternal antibodies cross the placenta and provide some protection. When active lesions are present at the time of labor, cesarean delivery is typically recommended to reduce the baby’s exposure to the virus.