Q and A

Question

Chances of infecting partner if I have an undetectable viral load?

5 February 2018. Related: All topics, CD4 and viral load, HIV transmission, Sero different couples.

I have been positive for three years now and started treatment two months ago. If my viral load is undetectable can I still infect someone? Are the chances of infecting my partner still the same if we had unprotected sex?

Answer

Answer: Simon Collins

Thank you for your questions.

In 2018, the answer to your question is a clear “no”.

Having an undetectable viral load makes HIV untransmittable. The evidence for this is at this link:
https://i-base.info/htb/32308

This was already believed by some experts in 2008 (when this question was first answered). The statement on behalf of the Swiss Federal Commission for HIV and AIDS authored by four of Switzerland’s foremost HIV experts said that an HIV infected person on ART with an undetectable viral load cannot transmit HIV through sexual contact. This information was published in the Bulletin of Swiss medicine in January 2008 was largely based on data from heterosexual sex.

See this factsheet on the Swiss Statement.

Note: This answer was updated in February 2018 from a question first posted online in February 2008.

45 comments

  1. Lila •

    My partner is HIV positive, he has reached an ‘undetectable’ level for almost a year now. What are my chances of contracting the virus? We always use protection when engaged in sexual acts. Are my chances greater with different kinds of sex? we engage in vaginal and anal intercourse, also in oral sex.

  2. Rebecca McDowall •

    Hi Lila,
    Please see our testing and transmission guide which discusses this in detail.

  3. Rebecca McDowall •

    Hi Elizabeth, please have a look at our pregnancy guide and the swiss statement for information about this and let me know if you have any questions after looking there.

  4. Elizabeth •

    I am HIV positive lady and my boyfriend is negative but we have attempted to have intercourse without using protection. I am on medication and we are planning to get pregnant early June but l don’t know how safe l am for him to do that.what if my viral load is undetectable and l have unprotected sex with him in my ovulation days,will l not infect him?

  5. Rebecca McDowall •

    Hi Maggie,

    I’m sorry to hear about your partner’s recent diagnosis. It’s important that you do start using condoms now, to prevent becoming infected yourself. If you get tested three months after the last time you had protected sex you will know that you are not positive. We have a guide to HIV testing and risks of sexual transmission which will answer many of the questions you have.

  6. Maggie •

    My partner is positive and so far I’m negative but we have been having unprotected sex for 2 years. Now what do I do start using condoms now and keep testing myself ?

  7. Rebecca McDowall •

    i-Base no longer answers individual questions about risks of HIV transmission or HIV testing. Information on both these subjects is now online in two resources:
    A FAQ page on testing and transmission:
    http://i-base.info/qa/faq/hiv-transmission-and-testing
    And a more detailed but easy to read guide to testing and sexual transmission:
    http://i-base.info/guides/testing

  8. derrick •

    I had sex with a woman but I used a condom but it later broke. 3 days later I developed genital herpes and l found out the woman is on ARVs since 2010. Is it possible that I have been infected with HIV too?

  9. Svilen Konov •

    Yes, you can. The chances are low, but are there…

  10. ian •

    Thanks for the answer.
    So what are the risks with anal sex between 2 men, can you still pass on the virus even though the person is undetectable.