People on HIV treatment tend to overestimate their chances of passing the virus to others. This holds true despite research suggesting that having an undetectable viral load makes transmitting HIV highly unlikely, if not impossible. Interested in how people with HIV perceive their own infectiousness, researchers studied 1,800 individuals starting antiretroviral (ARV) treatment for the first time.

After 48 weeks of treatment, just half of the participants considered themselves less infectious than before starting ARVs. Only 99 people saw themselves as noninfectious; eight people in this group had a detectable viral load. The researchers found no apparent connection between participants’ viral suppression and their perception of their infectiousness.

Those who were younger and more educated were more likely to report seeing themselves as less infectious after starting treatment, while African Americans and those with fewer than 50 CD4s at the beginning of the study were less likely to do so.

Raphael J. Landovitz, MD, MSc, associate director at the University of California, Los Angeles Center for Clinical AIDS Research & Education and the head of the study, says, “We think this highlights some important opportunities for finding populations that need more education about what it means for their sexual partners in terms of their infectiousness [when they start HIV treatment].”