Question
What is the risk to my partner with an undetectable viral load?
23 May 2013. Related: All topics, HIV transmission.
I was diagnosed as positive 3 years ago and have been on treatment since. I am doing very well and am stable and undetectable with a good CD4 count.
I had unprotected sex with my boyfriend (I am a woman) – he didn’t ejaculate inside me – but we had sex for some time. Can I pass HIV to him even if I am undetectable? Is he at risk?
I read somewhere that the chances are very small because of my stable undetectable condition. Thanks for any information.
Answer
The risk is dramatically reduced by having an undetectable viral load on treatment, but there is still likely to be some risk. Some estimates are that this might be as low as 1 in several thousand for one episode of heterosexual vaginal sex, but some are even lower still.
So you are right that the rates are likely to be low, but they are unlikely to be zero.
The i-Base guide to HIV transmission explains this in more detail.
See the section on viral load:
https://i-base.info/guides/testing/viral-load
And also this information from a different guide about Treatment as Prevention:
https://i-base.info/guides/starting/treatment-as-prevention-tasp
There is very little data on the risk from heterosexual anal sex and even less for risks fro gay men. The impact of treatment is still likely to lower this but we don;t know what level of risk is left.