People with HIV who interrupt their antiretroviral (ARV) treatment as part of a study experience a rapid rebound of the viral load in their semen, aidsmap reports. This finding indicates that such study participants are at a significant risk of transmitting the virus through condomless intercourse while they are off ARVs.

Publishing their findings in the journal AIDS, researchers analyzed the viral load in blood and semen among 10 HIV-positive male participants of a randomized placebo-controlled vaccine study called VR102/ANRS149-LIGHT. The men all had a fully suppressed viral load thanks to ARV treatment.

At week 36 of the study, the participants interrupted their ARV treatment. They were able to go back on ARVs 12 weeks later—or sooner—if their virus rebounded.

The participants provided blood and semen samples at week 36, 38, 40, 42 and 48 of the study.

At week 36, all the participants had a blood viral load below 20. Eight of the participants experienced viral rebound in their blood within two weeks; all of the men experienced viral rebound within eight weeks.

The men’s viral load was also undetectable in all cases at week 36. Four participants developed a detectable viral load in their semen within two weeks of the treatment interruption, and another four did so within four weeks. Samples were missing from the remaining two men.

The viral load in the men’s semen peaked at over15,000, compared with 125,000 in their blood.

To read the aidsmap article, click here.