Studies show that “people who take [HIV meds] 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.” That was the conclusion of a “Dear Colleague Letter” from the Centers for Disease Control and Prevention (CDC). That’s also the message of the “Undetectable = Untransmittable” (U=U) campaign. The CDC stated that when HIV meds result “in viral suppression, defined as less than 200 copies/milliliter, 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.”