Real-world research among heterosexual, mixed-HIV status South African couples shows that being on antiretroviral (ARV) treatment is associated with a 77 percent lower rate of transmission, aidsmap reports. Publishing their findings in Clinical Infectious Diseases, researchers conducted a longitudinal population-based study of 17,106 adults in northern KwaZulu-Natal province in South Africa, where 29 percent of residents are HIV positive and transmission rates are high.

The study ran from 2005 to 2013 (ARV treatment was introduced in 2004), during which the participants spent a cumulative 60,349 years in follow-up. The investigators identified 2,029 HIV-negative people who lived with a partner, including 196 who had an HIV-positive partner. Of the 196 HIV-positive partners, 20 were taking ARVs at the study’s outset and another 56 started treatment during the study.

The participants were tested for HIV on average about once a year, as part of a larger study.

The HIV infection rate was 5.6 percent per year among those whose HIV-positive partner was not on treatment, compared with 1.4 percent per year among those with a partner on HIV treatment. Thus, treating the virus was associated with a 77 percent reduced risk of transmission. The viral suppression rate among province residents treated for HIV before 2010 was also 77 percent.

The infection rate among HIV-negative people with HIV-negative partners was 0.3 percent per year and 3.2 percent among those who said they were not in a relationship.

To read the aidsmap article, click here.

To read the study abstract, click here.