A few years ago, large randomized controlled research studies of serodiscordant couples started to offer definitive evidence that effective HIV treatment prevents HIV transmission. The HIV community learned that people who maintain “undetectable” viral loads do not transmit HIV to sex partners from studies including HPTN 052 and PARTNER. Years before results from these landmark studies were released, the Swiss Statement offered the perspective that people with completely suppressed viral loads are not sexually infectious.

men holding handsNow, researchers want to know: Is this message reaching people living with HIV? And, if so, how is it changing how people who maintain undetectable viral loads have sex?

A team of researchers recently investigated this question with HIV-positive men who have sex with men in San Francisco. A sample of 68 men answered survey questions about how they were having sex over the previous six months and if they had a detectable viral load (among other questions). In addition to asking men about their viral load (i.e. if they had a detectable or undetectable viral load), the researchers also verified viral loads using a viral load lab test.

Overall, the researchers found that men were highly accurate in saying whether or not they were undetectable, and were likely using that information to make informed decisions on how to have sex. (The size of this study’s sample was small, however, which makes the study’s outcomes susceptible to bias and limits generalizability.)

Of the 68 men in the sample, 59 self-reported that they were undetectable. A total of 57 of these men (96.6%) had undetectable viral loads (<200 copies/mL) when they were checked with a viral load lab test. Said another way, 96.6% of men who said they were undetectable, actually were. Most men who had detectable viral loads (78%) knew and reported that they had detectable viral loads.

“I wasn’t surprised by this finding,” said H. Fisher Raymond, DrPH, the study’s corresponding author. “In San Francisco, for example people largely know their HIV status. Because we have good testing services and also many treatment options, men who have sex with men are generally well-connected to the health service system, and educated and savvy about their health.”

The study also showed that men were having sex differently if they knew they were undetectable. Men who were undetectable were less likely to use “seroadaptive” strategies (using condoms all of the time, not having anal sex) than men who were not undetectable. This study suggests, if not proves, that men living with HIV in San Francisco are incorporating treatment as prevention in their own lives.

“For folks living with HIV, one of our biggest fears is passing the virus onto our partners,” said Jimmy Gale, manager of HIV-positive services at San Francisco AIDS Foundation (who was not affiliated with the study). “For long-term survivors, the message that undetectable equals untransmittable is an especially groundbreaking revelation. Many folks living with HIV have been too afraid to have the sex lives they needed. Sex is something that is meant to be enjoyed. Fucking without fear is a luxury that has been out of reach for too long. Getting to an undetectable viral load has more benefits than just staying healthy, it’s also about living your life to its full capacity.”

In the study, men who reported having detectable viral loads were more likely to use condoms all the time and report not having anal sex. “This finding is positive in terms of HIV prevention. The guys who thought they weren’t undetectable were possibly being more careful,” said Raymond.

Although Raymond said he hopes that the effectiveness of treatment as prevention is an encouragement for people to become, and stay, undetectable, he offers caution against losing momentum on sexually transmitted infection prevention.

“Treatment as prevention is doing really good things in terms of HIV, but does nothing to prohibit the transmission of gonorrhea, chlamydia or syphilis. The community needs to be aware of this, so we really just can’t say this enough.”

Condoms prevent HIV and also sexually transmitted infections. Read more about how well condoms work, on BETA. Read more about how well effective HIV treatment prevents HIV transmission on BETA, and find out about the Undetectable = Untransmittable campaign by Prevention Access Campaign.

Author: Emily Newman


Guigayoma, J. and colleagues. Self-perceived viral load and sexual risk behavior among known HIV-positive MSM in San Francisco, 2014JAIDS, 2017.