I wrote this short post only to link to the full statement that the Centers for Disease Control issued on September 27, 2017. That statement confirms what every HIV medical expert already knew: HIV+ patients who are on suppressive antiretroviral therapy with an undetectable viral load do not transmit HIV.
Here is the relevant excerpt:
When ART results in viral suppression, defined as less than 200 copies/ml or undetectable levels, it prevents sexual HIV transmission. Across three different studies, including thousands of couples and many thousand acts of sex without a condom or pre-exposure prophylaxis (PrEP), no HIV transmissions to an HIV-negative partner were observed when the HIV- positive person was virally suppressed. This means that people who take ART daily as prescribed and achieve and maintain an undetectable viral load have effectively no risk of sexually transmitting the virus to an HIV-negative partner.
However, the statement did go on to state that too many HIV+ gay and bisexual men are slipping through the cracks, with only 61% of diagnosed HIV+ patients having undetectable viral loads. Black and hispanic/latino men are most likely to lack access to the necessary treatments for their HIV.
This is why it is still a good idea to be on PrEP to protect yourself from HIV if you are having unprotected sex outside of a monogamous relationship. You have no reason to trust that your random hookup is being honest about his HIV status. He might not even know that he has HIV. [Editor’s note: this entire last paragraph is mine, although I am sure the CDC would agree with me].