According to the Public Health Agency of Canada’s recent review of scientific literature, the risk of transmitting HIV when an individual has a viral load below 200 is “negligible,” aidsmap reports. This finding, researchers say, backs the assertion that Canadian laws that criminalize sex among people with an undetectable viral load are unjust.

Publishing their findings in CMAJ, researchers from the Canadian agency conducted an overview and systematic review of relevant studies published through April 2017. This meant that their paper did not take into account important data sets from the PARTNER2 and Opposites Attract studies, which saw zero transmissions among people with undetectable viral loads and the inclusion of which would have added further statistical heft to the Canadian authors’ conclusions.

The final analysis included 12 papers. There were no transmissions of HIV among study participants when they had a viral load below 200 according to consecutive tests conducted every four to six months. Consequently, the researchers concluded that the risk of HIV transmission in the context of a sustained undetectable viral load was “negligible.”

One paper provided data on the risk of transmission when the HIV-positive partner was not on antiretroviral (ARV) treatment and when that individual used a condom for sex with an HIV-negative partner. The transmission rate in this context was 1.14 per 100 cumulative years of follow-up.

Eleven studies provided data on transmissions when the HIV-positive partner was on ARVs but had a detectable viral load. There were 23 transmissions in this context during 10,511 cumulative years of follow-up, for a transmission rate of 0.22 per 100 cumulative years of follow-up.

Using condoms when an HIV-positive partner is not on ARVs is associated with a “low” risk of transmission, the study authors concluded, basing their assessment on a 2012 Cochrane Collaboration review on the subject. That paper found a transmission rate of 1.14 per 100 cumulative years of follow-up.

To read the aidsmap article, click here.

To read the study abstract, click here.