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How HIV is transmitted

Sponges symbolising buttocks

For someone to get HIV, an infectious fluid like blood or semen has to get inside their body. There are a number of ways that this can happen.

How do you get HIV?

During sex a body fluid of someone with HIV (such as blood, semen, vaginal or anal secretions*) can get inside another person. This allows the virus to enter their blood stream.

This can happen during:

  • vaginal sex
  • anal sex
  • sometimes, though very rarely, through oral sex
  • when an object (eg, a sex toy) that has a body fluid on it goes from inside one person and into another

* These are fluids or a kind of sticky lubrication that cover the inside of the vagina or anus

How HIV is not transmitted ››

Is risk lower with HIV treatment?

A large study called PARTNER has been looking at over 1,000 gay and straight couples where one partner is HIV positive and one is HIV negative. The study won’t finish until 2017 but early results have shown that where the HIV positive partner had an undetectable viral load and was on treatment, there were no cases of HIV transmission whether they had anal or vaginal sex.

If you have HIV, having untreated STIs could make it more likely that you’ll pass on HIV during unprotected sex. But if HIV drugs have made your viral load undetectable then STIs don’t appear to make you more likely to pass on HIV.

It is important to remember that these are preliminary findings so as the study goes on the advice may change, but this is what has been reported so far.

Before you make any decision about not using condoms, get advice from an HIV doctor or nurse practitioner.

Can I get HIV without having sex?

Yes, HIV can also be passed on if you inject drugs and share injecting equipment (needles, syringes, swabs, spoons and other items) that has been used by someone with HIV.

Also, a woman can give birth to a baby who also becomes infected. This could happen during child birth but can also take place while breastfeeding or in the womb before the baby is born. This is extremely rare in the UK because pregnant women take HIV medication to stop this happening.

In countries that don’t have strict checks on the safety of their blood supply (this began in the UK in 1985), receiving contaminated blood can pass the virus on. This could also happen in countries that don’t screen other blood products, organs or sperm.

Read more about different modes of transmission:

  1. HIV transmission through semen and vaginal fluid ››
  2. infected blood ››
  3. mother to baby transmission ››
  4. ways HIV is NOT transmitted ››

Symptoms of HIV infection ›› ››



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  • In your reference to risks associated with sharing equipment, you state "Swabs, spoons ...." Although I understand the risk which could be present from sharing a hollow bore needle, just exactly how can sharing spoons be an issue ?

    Posted 08:33 Wed 10 Dec 2014

The Information Standard: Certified member

This article was last reviewed on 9/1/2017 by Anna Peters

Date due for the next review: 8/2/2017

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The easiest and most effective precaution to take against most STIs is using a condom.