Q and A


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

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?


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:

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.


  1. Lisa Thorley

    Hi Mukasa,

    When someone has an undetectable viral load, they can’t transmit HIV sexually. For more info, please see here:


  2. Mukasa

    I’ve been undetectable for 2 years. Can I transmit HIV to my partner?

  3. Lisa Thorley

    Hi Nshekanabo

    Please see the above post, and Q’s 5 and 9 here:


  4. Nshekanabo

    I have spent more than a half year with my pattern when we are opposite in our status but am still negative but with so many questions on it

  5. Lisa Thorley

    Hi Ntkozo,

    When someone has an undetectable viral load they cannot transmit HIV to a sexual partner. Therefore, your partner isn’t at risk. For more info, please see here: