New Study Shows Some Risk is Not No Risk
A study of 101 gay men at the Fenway Health HIV clinic in Boston, Mass., found that a quarter of men with undetectable viral loads in their blood nonetheless had detectable HIV in their semen.
The results also found that although seminal viral load in these men was low researchers suggest that this is still enough to be one of the explanations for ongoing transmission in gay men despite a high proportion being on antiretroviral therapy.
Importantly, the study findings show a very strong association with detectable HIV in semen and having a current sexually transmitted infection (STI). Six of the eight men whose HIV were undetectable in blood but detectable in semen had a urethral STI. After adjusting for other factors the researchers concluded that men who had an STI and/or urethritis were 29 times more likely to have viral discordancy.
"Ultimately, this confirms the importance of offering both STI screening and HIV testing because of the strong association between having detectable HIV in semen and having a co-occurring sexually transmitted infection," Gay City Health Project Executive Director Fred Swanson told EDGE. Gay City provides gay, bisexual, and transgender men free HIV/STI testing in Seattle.
Swanson says that important part of the work they do is "helping our clients to understand the risks they may be taking and to make a plan to reduce the likelihood that HIV or another STI would be transmitted when they are having sex."
Although new breakthroughs can be exciting, this study points to the fact that no prevention strategy is foolproof.
"There are many great reasons to connect HIV-positive guys to treatment options, primarily for their own health," he said. "Although the potential prevention benefits are compelling, this study demonstrates that even achieving an undetectable viral load in your or your partner's blood doesn't necessarily prevent HIV from being transmitted during sex."
"Whether you're living with HIV or not, having a comprehensive risk reduction strategy that includes, among other things, regular screening for STIs, is very important if you are sexually active," said Swanson.
In the Boston study, participants were on average 43 years old and three-quarters were white. They had all been on antiretroviral therapy for more than three months and 80% for over a year.
Nearly three-quarters were judged as being at high risk of acquiring an STI because they had had unprotected sex in the last three months. Nine of the men were diagnosed with an STI (gonorrhea, syphilis, chlamydia or non-gonococci urethritis) and 24 had leukocytospermia or white cells from the immune system in the sperm, indicative of urethral inflammation.
Eighteen of the 101 men had a detectable viral load in their blood. Nine of these 18 men also had detectable HIV in their semen (50%).
Of the 83 men without detectable HIV in their blood, 21 (25%) had detectable HIV in their semen.
So a person could be HIV+ and have an undetectable viral load. The question here is: how infectious are they at that point?
"An equally important difference to understand is that between 'exposure' and 'infection,'" Eric Marlowe Garrison, a certified sex counselor and Diplomate of the London School of Hygiene & Tropical Medicine told EDGE. "I could go have unprotected anal intercourse tonight with an HIV-positive individual, be exposed to the virus, and not infected by it. Realize though, I cannot be infected unless I am exposed."
So the health question is this: how risky is unprotected sex between an HIV-negative person and an HIV-positive person with an undetectable viral load?