Terrence Higgins Trust uses cookies to improve your experience of our websites. For more information or to change the use of cookies, please click here.

Accept and Close

HIV transmission

how hiv is not passed on

Some body fluids, such as saliva, sweat and urine, do not have enough HIV in them to infect someone. HIV is not passed on by spitting, sneezing or coughing. If someone with HIV is on effective treatment with an undetectable viral load, they cannot pass on HIV.

Jump to:


How is HIV transmitted?

If someone with HIV is infectious they can pass on HIV through the following body fluids:

  • blood
  • semen (including pre-cum)
  • vaginal fluid
  • anal mucus
  • breast milk.

This can be prevented by using a condom during sex, or by the HIV negative person taking Pre-exposure prophylaxis (PrEP).

If you’re an injecting drug user, never share drug injecting equipment.

During pregnancy your doctor will advise you how to protect your baby.

If someone with HIV is taking effective HIV medication and has an undetectable viral load, they cannot pass on HIV. It can take up to six months on treatment to become undetectable.


How is HIV passed on during sex?

During sex body fluids from someone with HIV can get inside a person who is HIV negative.

If the person with HIV has a detectable viral load the virus can enter the HIV negative person’s bloodstream. This can happen during vaginal and anal sex (and sometimes oral sex too, though this is much less common).

It can also happen when an object (eg, a sex toy) that has infectious body fluids on it is put inside an HIV negative person.

It’s also important to remember that if you have sex without a condom other sexually transmitted infections (STIs) can be passed on.

Sex without a condom can also result in pregnancy if other contraception is not being used.

Some sexual activities have a greater risk of HIV infection than others.


When is a person with HIV infectious?

Someone with HIV is infectious if they have a detectable viral load.

The risk is highest during the first few months after infection when they have very high levels of the virus in their body fluids and may not yet have been diagnosed.

Early diagnosis means you can start treatment to reduce your viral load to undetectable levels and protect your health.


How is HIV not passed on?

Many activities pose no risk of getting or passing on HIV:

You cannot pass on HIV by:

  • kissing
  • hugging
  • shaking hands with somebody
  • any other normal social contact
  • sharing space with someone
  • sharing a toilet
  • sharing household items such as cups, plates, cutlery, or bed linen.

In the UK, there are safeguards in place to ensure that blood, organs and sperm donated for use in medical procedures are not HIV-infected.

A recent study called PARTNER found that people who are on effective HIV treatment and have an undetectable viral load cannot pass on HIV.


What is effective treatment?

The Partners PrEP study found that it can take up to six months on treatment for someone's viral load to become undetectable.

Effective treatment therefore means that someone has been taking it as prescribed for at least six months and has an undetectable viral load.


What about blood containing HIV?

In a medical setting, it's possible for HIV to be transmitted by someone accidentally cutting themselves with a blade or needle they have used to treat a person living with HIV.

This is called a needlestick injury and the risk of being infected in this way is very low - and can only happen if the person with HIV has a detectable viral load.

However, if someone thinks they have been exposed to HIV through a needlestick injury, Post-exposure Prophylaxis (PEP) may be an option.


How long can HIV survive outside the body?

Once outside the body, HIV usually can’t survive for very long. Coming into contact with blood or semen, from a person who has a detectable viral load, that has been outside the body doesn’t generally pose a risk for HIV transmission.

Similarly, the risk of passing on HIV to someone else if you have a detectable viral load and injure yourself is also very low. Wash away any blood with soap and hot water and cover the wound with a sticking plaster or dressing.


More on living with HIV:


This content is currently being reviewed and will be updated shortly.


Next: The immune system ››

‹‹ Previous: What is HIV?

 

Rate:

Whole Star Whole Star Whole Star Whole Star Whole Star (1 vote cast) Please log in or register to vote. What's this?

Save:

Please log in or register to add this article to My favourites. What's this? Adding an article to My favourites will allow you to easily come back to it later or print it.


Your comments

You will need to be logged in before you can leave a comment.

Please log in using the form on the top right of the page or register.

The Information Standard: Certified member

This article was last reviewed on 9/10/2017 by Anna Peters

Date due for the next review: 9/10/2020

Content Author: S. Corkery (NAM)

Current Owner: Kerri Virani

More information:

HIV Transmission Risk Persists During the First 6 Months of Antiretroviral Therapy, Mujugira A1, Celum C, Coombs RW, Campbell JD, Ndase P, Ronald A, Were E, Bukusi EA, Mugo N, Kiarie J, Baeten JM; Partners PrEP Study Team
National Center for Biotechnology Information
US National Library of Medicine
2016 Aug 15;72(5):579-84. doi: 10.1097/QAI.0000000000001019

HIV treatment as prevention and HPTN 052, Cohen MS1, McCauley M, Gamble TR
National Center for Boiotechnology Information
US National Library of Medicine

Sexual Activity Without Condoms and Risk of HIV Transmission in Serodifferent Couples When the HIV-Positive Partner Is Using Suppressive Antiretroviral Therapy, Journal of the American Medical Association: Alison J. Rodger, MD; Valentina Cambiano, PhD; Tina Bruun, RN; Pietro Vernazza, MD; Simon Collins; Jan van Lunzen, PhD; Giulio Maria Corbelli; Vicente Estrada, MD; Anna Maria Geretti, MD; Apostolos Beloukas, PhD; David Asboe, FRCP; Pompeyo Viciana, MD1; Félix Gutiérrez, MD; Bonaventura Clotet, PhD; Christian Pradier, MD; Jan Gerstoft, MD; Rainer Weber, MD; Katarina Westling, MD; Gilles Wandeler, MD; Jan M. Prins, PhD; Armin Rieger, MD; Marcel Stoeckle, MD; Tim Kümmerle, PhD; Teresa Bini, MD; Adriana Ammassari, MD; Richard Gilson, MD; Ivanka Krznaric, PhD; Matti Ristola, PhD; Robert Zangerle, MD; Pia Handberg, RN; Antonio Antela, PhD; Sris Allan, FRCP; Andrew N. Phillips, PhD; Jens Lundgren, MD, JAMA. 2016;316(2):171-181. doi:10.1001/jama.2016.5148

Viral load, Michael Carter, Greta Hughson, NAM, Aidsmap, March 2014

More confidence on zero risk: still no transmissions seen from people with an undetectable viral load in PARTNER study, Gus Cairns NAM, Aidsmap, July 2016

Open your eyes to STIs, NHS Choices, Nov 2015

When sex goes wrong, NHS Choices, Nov 2015

Pre exposure prophylaxis, Roger Pebody, NAM, Aidsmap, October 2016

Can post exposure prophylaxis (PEP) stop me getting HIV?, NHS Choices, Sep 2015

STIs make no difference to transmission risk in those with suppressed viral load: Davies O et al. Impact of rectal gonorrhoea and chlamydia on HIV viral load and inflammatory markers in the rectum; potential significance for onward transmission. BHIVA conference, Thursday 23 April 2015, abstract O19

Impact of rectal Gonorrhoea and Chlamydia on HIV viral load in the rectum; potential significance for onward transmission, Olubanke Davies, Sinead Costelloe, Juan Tiraboschi, John White, Siobhan O’Shea, Julie Fox, Presentation from BHIVA conference 21-24 April 2015

Men taking HIV treatment have undetectable viral loads in the rectum; sexually transmitted infections make no difference, NAM, Aidsmap, Roger Pebody, 24/4/15

Condoms, NHS Choices, 13/1/15

Wu L Biology of HIV mucosal transmission. Curr Opin HIV AIDS 3(5): 534-540, 2008

Shugars DC et al. The role of the oral environment in HIV-1 transmission. JADA 129:851-858, 1998

Skolnik P et al. Absence of infectious HIV–1 in the urine of seropositive individuals. J Inf Dis 160(6): 1056-1060, 1989

Mueller AJ et al. Infrequent detection of HIV-1 components in tears compared to blood of HIV-1-infected persons. Infection 20(5):249-52, 1992

Cohen M et al. Antiretroviral treatment to prevent the sexual transmission of HIV-1: results from the HPTN 052 multinational randomized controlled ART. Sixth International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention, Rome, abstract MOAX0102, 2011.

Advisory Committee on Dangerous Pathogens Protection against blood-borne infections in the workplace: HIV and Hepatitis (draft guidance). Health and Safety Executive, 2008.