What is my risk of spreading herpes? Herpes Transmission Risk

Last Updated on September 7, 2021 by Valinda Riggins Nwadike, MD, MPH

One of the most common questions we receive is about herpes transmission and the risk of spreading the virus to a new partner.

HSV1 & HSV2 is transmitted via skin-to-skin contact – not bodily fluids, blood, surfaces, towels, bedding, toilets, or otherwise, just skin-to-skin contact. From there, inoculation must also occur for the infection to spread, and this happens via a point of entry into the system. Coming in contact with the virus on your arm, for example, won’t necessarily lead to infection, unless your arm also has a small cut, abrasion, sore, or tear providing entry for the virus into the human body – inoculation.

The Mucous Membranes

This is where the mucosa (mucous membranes) comes into play. The mucous membranes, highly porous tissues involving absorption and secretion, line cavities of the body exposed to the environment. They are continuous with the skin and reside in the nostrils, the mouth, the lips, the eyelids, the ears, the vulva, the vagina, the urethra, and the anus.

These membranes are designed to trap unwanted and harmful pathogens with mucous. At which point, the immune system is sent to kill the otherwise invasive infections trapped in the mucosa. However, the immune system is not able to combat all pathogens.

In the case of sexually transmitted infections and diseases, HSV included, the mucous membranes trap the pathogen, providing an entry point to the body, the immune system is unable to effectively combat the infection, and the pathogen enters the system.

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Asymptomatic Shedding

Once infected with HSV1 or HSV2, a person is capable of transmitting the virus forever, even when there are no symptoms present.

Transmission that occurs when there are no visible symptoms is a result of asymptomatic viral shedding.

Viral shedding means the virus is active on the skin. HSV can shed before an active outbreak (the prodromal period), during an outbreak, during the healing process following an outbreak, and also at random when there are no noticeable symptoms, and that is called asymptomatic viral shedding, or simply, asymptomatic shedding.

• In general, people with HSV1 asymptomatically shed the virus about 5%-10% of the time.
• In general, people with HSV2 asymptomatically shed the virus about 10%-20% of the time.

Over time, though, the percentage someone sheds the virus asymptomatically is said to decrease.

Is one type of herpes more easily spread than another?

No, not really.

Both HSV1 and HSV2 can be easily transmitted via skin-to-skin contact. HSV1 tends to prefer locations above the waist, such as the mouth, and HSV2 tends to prefer locations below the waist, such as the genitals, but both can also be easily spread to other parts of the body.

Both types are most contagious during active outbreaks – when visual symptoms are present – but they are also commonly spread when there are no recognizable symptoms through asymptomatic shedding.

Prevalence of Oral HSV1 – Cold Sores

In theory, oral HSV1 is the most easily acquired infection, because it is usually the first herpes simplex type someone encounters, and it is commonly spread by social kissing among relatives and friends. Children who have no prior infections with an HSV type do not have an acquired immune response and are most susceptible.

50% of Americans, by their teenage and young adult years, will have acquired HSV1 and will have the HSV1 antibodies, and by the time they reach age 50, 80-90% of Americans will have acquired HSV1.

In contrast, almost all HSV2 infections are encountered during teenage and adult years, once someone has become sexually active.

Is penis-to-vulva or vulva-to-penis riskier?

In general, someone with a vulva is more likely to contract an HSV infection than someone with a penis, because the majority of the vulva and vagina is comprised of mucous membranes. And while there are mucous membranes on the penis (the head of the penis, the foreskin, and the urethra), there is less exposed surface area on the penis that is made of mucous membranes than compared to the vulva and vagina.

That is why HSV transmission is actually most dependent upon the location of the body in contact with the virus rather than the gender of the person in question, because of exposure to mucous membranes themselves.

The greatest risk of transmission occurs anywhere there is contact by an infected area with a mucosa: the nostrils, the mouth, the lips, the eyelids, the ears, the anus, the vulva, the vagina, the glans penis (head of the penis), the glans clitoris, the urethra, the inside of the prepuce (foreskin), and the clitoral hood.

Percentage of HSV Risk

Let’s say you have a person with a penis who has HSV and person with a vulva who does not:

• If they avoid sexual activity during outbreaks, don’t use condoms regularly, and the person with a penis doesn’t take an antiviral therapy every day, the risk of transmission is about 10% per year, though there is a large range — from 7 percent to 31 percent — in different studies.

Let’s say you have a person with a vulva who has HSV and a person with a penis who does not:

• If they avoid sexual activity during outbreaks, don’t use condoms regularly, and the person with the vulva doesn’t take an antiviral therapy every day, the risk of transmission is about 5% per year.

Those percentages represent what studies consider an “average” sex life incorporating vaginal penetration over the course of one year’s duration, which, of course, is highly subjective.

Unfortunately, there is no available data yet on the rate of transmission between same-sex partners.

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