HIV is a virus that only transmits between people in specific ways. There are many myths about HIV transmission, and it is important to know the facts.
Understanding how HIV does and does not pass on helps prevent transmission and reduce the discrimination and stigma associated with HIV.
The number of new HIV diagnoses and the impact of the virus in the United States are decreasing thanks to effective preventive measures and treatments.
For example, antiretroviral therapy can reduce the amount of virus in the body to undetectable levels. When this happens, the virus cannot harm the body or pass on to another person.
In addition, pre-exposure prophylaxis (PrEP) medication offers a high level of protection by stopping the virus from taking hold if exposure occurs.
This article looks at the ways that HIV transmits, the ways that it does not, and how to keep it from passing on.
In most cases, people contract HIV through anal or vaginal sex or through sharing drug injection equipment, such as needles or syringes.
HIV can only transmit through certain body fluids:
- preseminal fluid
- rectal fluids
- vaginal fluids
- breast milk
Blood can carry more of the virus than other bodily fluids, so the highest risk involves exposure to blood that contains the virus.
HIV does not pass on through all contact with fluids that contain the virus, however. For transmission to occur, the fluid must come into contact with damaged tissue, the bloodstream, or mucous membranes, such as those in the genitals, rectum, or mouth.
If blood that contains HIV comes into direct contact with another person’s bloodstream, such as through an injection with a shared needle, this is very likely to transmit the virus.
HIV can transmit to a baby during pregnancy, birth, or breastfeeding. However, this is less common due to modern preventive measures and treatments.
According to the Centers for Disease Control and Prevention (CDC), HIV cannot transmit through:
- insect bites, including those from mosquitoes and ticks
- the air
- contact with saliva, tears, or sweat
- shaking hands, hugging, or closed-mouth kissing
- sharing toilets, dishes, or utensils
- eating food handled by someone with HIV
- sexual activities that do not involve fluid exchange, such as touching
HIV cannot survive long outside the body, so it does not transmit via surfaces.
The risks of contracting the virus through other methods of exposure, such as biting, scratching, and thrown bodily fluids, are either very small or nonexistent.
There is also little to no risk of contracting HIV via:
- Oral sex: However, having mouth ulcers, genital sores, or bleeding gums can increase the risk of transmission.
- Workplace exchanges: However, a puncture from a needle or another sharp object that contains the virus can lead to transmission.
- Blood transfusion or donated organs: Current screening practices in the U.S. are safe and well-regulated, making this transmission highly unlikely.
- Deep, open-mouth kissing: Transmission in this way is very rare, but it can happen if both people have oral sores or bleeding gums.
- Tattoos and body piercings: There have been no reports of transmission from tattoos or piercings in the U.S., though it is possible if the equipment or ink has been in contact with someone else’s blood.
Anyone can contract HIV, but several factors increase the risk. These include:
- sharing equipment used to inject drugs
- getting a tattoo with a shared needle or shared ink
- having anal or vaginal sex without a condom
- having a sexually transmitted infection
- having frequent exposure to fluids containing the virus, such as in laboratory, medical, or emergency settings
- using drugs and alcohol, which can impair judgment
- having exposure to the virus during childbirth, pregnancy, or breastfeeding
Some populations are more affected by HIV than others in the U.S., including Black and Latinx people and men who have sex with men.
According to the CDC, men who have sex with men received 69% of all new HIV diagnoses in the U.S. Anal sex without a condom is the most likely route of transmission because the risk of tissue damage is high.
People who are Black or Latinx are more affected largely due to systemic inequity in healthcare and the unequal distribution of resources.
In 2018, Black people received 42% of new HIV diagnoses in the U.S., Hispanic and Latinx people received 27%, and white people received 25%.
The prevalence of HIV also differs by region in the U.S. The South has the highest number of people living with HIV, and the Northeast has the highest HIV rate. The rate is the number of cases per 100,000 people.
What about breastfeeding?
If a person with HIV receives no treatment, the World Health Organization (WHO) report a 15–45% chance that they will pass on the virus to their infant during labor, delivery, or breastfeeding. This is due to contact with relevant body fluids.
Antiretroviral therapy can reduce the chances of transmission to below 5%. The WHO recommend that people with HIV combine exclusive breastfeeding with the use of antiretroviral therapy.
Some social factors that influence a person’s risk of HIV infection include:
- access to education about HIV transmission and prevention
- access to affordable healthcare
- discrimination and stigma in healthcare and society at large
- reduced negotiating power due to sex, gender, and financial or other status
Increased awareness of and access to antiretroviral therapy, preventive medication, and support services are effective ways to reduce the impact of HIV.
A range of effective strategies can now lower the risk of contracting HIV. These include:
- using PrEP, a preventive drug
- never sharing needles with another person
- using condoms during sex
- getting frequent HIV testing, for people with multiple sexual partners
- using gloves and other sterile equipment in medical settings
- taking emergency post-exposure prophylaxis (PEP) after possible exposure to the virus
When a person takes PrEP daily, it reduces the risk of contracting HIV via sex by about 99% and via needles by about 74%.
The U.S. Preventive Services Task Force updated their guidelines in 2019. They now recommend that only people who have recently received negative results from HIV screening be candidates for PrEP. People who have a high risk of exposure to the virus should take PrEP once a day.
People with HIV who are pregnant or plan to be should discuss ways to mitigate the risk of transmission with their doctors, including the choice of whether to breastfeed.
Due to advances in prevention and treatment, the number of new HIV diagnoses in the U.S. has reduced by more than two-thirds since the mid-1980s.
Undetectable = untransmittable
Using antiretroviral therapy consistently as prescribed can reduce the risk of transmission to virtually zero. It slows or stops the activity of HIV in the body.
When someone with HIV has a viral load of under 200 copies of the virus per milliliter of blood, doctors consider the virus undetectable. At this point, the virus cannot transmit to others.
It is important to keep following the treatment plan and attend regular checks to ensure that the viral load remains undetectable.
Many people with HIV experience no symptoms. A person can only know their HIV status by taking a test.
The CDC recommend that everyone aged 13–64 have at least one HIV test.
Early testing, diagnosis, and treatment are the most effective ways to stop the progression and transmission of the virus.
Frequent testing is an inexpensive and effective way to stop the spread of HIV. It is especially important to test:
- when planning to become pregnant
- after becoming pregnant
- before having sex with a new partner
People with a high risk of contracting the virus should get tested every 3–6 months — including sex workers, first responders, and others who come into regular contact with body fluids, as well as people who use needles that may be shared.
What is my risk level?
The CDC provide an online risk estimation tool informed by up-to-date evidence. It helps a person determine their risk of contracting HIV from various activities.
HIV can only transmit in certain situations through contact with blood, rectal fluids, vaginal fluids, breast milk, and semen or preseminal fluid.
There are many ways to reduce the risk of contracting HIV, including using condoms when having sex, taking PrEP, and never using shared needles.
In the U.S., HIV has a disproportionate impact on certain groups, including men who have sex with men and Black and Latinx people.
With modern antiretroviral therapy, fewer people contract HIV. People with continuous access to this treatment are able to live long, healthy lives, and the risk of transmission is significantly reduced, often to zero.