What Is Considered an Open Wound for HIV Transmission?

Estimating Transmission Risk by Exposure Type

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Any small wound or break in the skin is considered a potential entry point for blood or certain bodily fluids—vaginal fluids, semen, pre-seminal fluids, or rectal fluids—to transmit HIV. To reduce your risk of HIV, it's important to fully understand how transmission occurs, how to assess an open wound, and ways you can reduce your risk of exposure.

How HIV Transmission Occurs

When discussing HIV risk, it's important to first establish the four conditions that must take place in order for HIV transmission to occur:

  1. There must be body fluids in which HIV can thrive. This includes semen, blood, vaginal fluids, or breast milk. HIV cannot thrive in the open air or in parts of the body with high acid content, such as the stomach or bladder.
  2. There must be a route of transmission by which body fluids are exchanged. Primary routes of transmission include certain sexual activities, shared needles, healthcare exposure, or transmission from mother to child.
  3. There must be a means for the virus to reach vulnerable cells inside the body. This can occur through a rupture or penetration of the skin or through mucosal tissues of the anus or vagina. HIV cannot penetrate intact skin.
  4. There must be sufficient levels of virus in the body fluids. This is why saliva, sweat, and tears are unlikely sources of HIV since the concentration of the virus in these fluids is considered insufficient. Neutralizing enzymes in saliva (called secretory leukocyte peptidase inhibitors, or SLPIs) are known to greatly diminish HIV's ability to thrive.

Determining whether an activity is "high risk" or "low risk" is, therefore, dependent upon how efficiently an activity satisfies each of these four conditions.

Young Couple Kissing On Bed
Nattakorn Maneerat / EyeEm / Getty Images

Assessing Open Wounds

HIV can be transmitted when infected blood, vaginal fluids, semen or pre-seminal fluid, or rectal fluids, come into contact with any wound or damaged tissue, including small cuts, scratches, or open sores.

This means that any broken skin or sores on the genitals increases the risk of HIV transmission during sexual activity. For example, the presence of an STI or genital ulcer increases the risk of HIV by anywhere from 20% to 300%.

HIV isn't transmitted via saliva during kissing, but in rare cases, it can be spread through kissing if both partners have sores or bleeding gums.

Reducing Risk of Exposure

Assigning an actual percentage to the "riskiness" of a certain activity is a tricky business. While statistics may suggest that there is only a 1-in-200 (or 0.5%) chance of getting infected by a particular activity, that doesn't mean you can’t get infected after only one exposure.

Instead, a 0.5% "per exposure" risk is meant to indicate that an average of one infection will occur out of 200 people who engage in a particular activity. It doesn't mean that you need to do something 200 times in order to get infected.

Keep in mind that risk estimates are based on two factors and two factors alone—that one person has HIV and the other doesn't. Additional co-factors, such as co-existing sexually transmitted infections (STIs), general health, and the infected person's viral load, can further compound risk until a low-risk activity is suddenly considerably higher.

Estimated HIV Transmission Risk Per Exposure

The estimates below should not be considered definitive but rather serve as a means to understand the relative risk of HIV by exposure type. The numbers are based on a meta-analysis of several large-scale studies which looked specifically at per-exposure risk.

Exposure Exposure Type Per-Exposure Risk
Anal Receptive anal sex with ejaculation 1.43% (1 in 70)
Receptive anal sex without ejaculation 0.65% (1 in 154)
Insertive anal sex, uncircumcised 0.62% (1 in 161)
Insertive anal sex, circumcised 0.11% (1 in 909)
Vaginal Vaginal sex, female-to-male (high-income country) 0.04% (1 in 2500)
Vaginal sex, male-to-female (high-income country) 0.08% (1 in 1250)
Vaginal sex, female-to-male (low-income country) 0.38% (1 in 263)
Vaginal sex, male-to-female (low-income country) 0.3% (1 in 333)
Vaginal sex, asymptomatic HIV 0.07% (1 in 1428)
Vaginal sex sex, late-stage symptomatic HIV 0.55% (1 in 180)
Oral Oral-penile (fellatio), receptive 0% to 0.04% (1 in 2500)
Oral-penile (fellatio), insertive 0% to 0.005% (1 in 20000)
Oral-anal (anilingus), either partner Negligible
Oral-vaginal (cunnilingus), either partner Negligible
Percutaneous Shared injecting drug use, non-disinfected 0.67% (1 in 149)
Occupational needlestick injury 0.24% (1 in 417)
Non-occupational needlestick w/ discarded syringe Low to negligible
Blood transfusion (U.S.) 0.0000056% (one in 1.8 million)
Pregnancy Mother-to-child, no antiretroviral therapy (ART) 25% (1 in 4)
Mother-to-child, ART two weeks prior to delivery 0.8% (1 in 125)
Mother-to-child, on ART with undetectable viral load 0.1% (1 in 1000)

The purpose of understanding relative risk is to establish the means by which to reduce your personal risk of infection or the risk of transmitting HIV to others. Oftentimes, it takes little to mitigate risk. For example, the consistent use of condoms correlates to a 20-fold decrease in HIV risk, while choosing insertive fellatio over insertive anal sex results in a 13-fold decrease.

Arguably the most important factor in assessing the likelihood of HIV transmission is the infected person's viral load. Data suggest that the risk of a person living with HIV with an undetectable viral load transmitting the virus is essentially zero.

The strategy called treatment as prevention (TasP) strongly supports the use of antiretroviral therapy to reduce the infectivity of a person with HIV. It also reinforces the need for early testing to mitigate risk in mixed-status (serodiscordant) couples.​

Knowing your serostatus (having or not having detectable antibodies) and that of your partner allows you to make an informed choice on how to better protect yourselves. This may include abstaining from high-risk activities, using condoms, or exploring pre-exposure prophylaxis (PrEP) as a means to reduce the HIV-negative partner's susceptibility to infection.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. HIV transmission.

  2. Sousa JD, Müller V, Vandamme AM. The impact of genital ulcers on HIV transmission has been underestimated—a critical reviewViruses. 2022;14(3):538. doi:10.3390/v14030538

  3. Boily MC, Baggaley RF, Wang L, et al. Heterosexual risk of HIV-1 infection per sexual act: systematic review and meta-analysis of observational studiesLancet Infect Dis. 2009;9(2):118–129. doi:10.1016/S1473-3099(09)70021-0

  4. Patel P, Borkowf CB, Brooks JT, Lasry A, Lansky A, Mermin J. Estimating per-act HIV transmission risk: a systematic reviewAIDS. 2014;28(10):1509–1519. doi:10.1097/QAD.0000000000000298

  5. Centers for Disease Control and Prevention. HIV Treatment As Prevention.

Additional Reading

By James Myhre & Dennis Sifris, MD
Dennis Sifris, MD, is an HIV specialist and Medical Director of LifeSense Disease Management. James Myhre is an American journalist and HIV educator.