HealthDay News — HIV transmission is highly unlikely among heterosexual couples who have sex without condoms when one partner carries the virus but takes antiretroviral therapy, according to a study published in the July 12 issue of the Journal of the American Medical Association, a theme issue on HIV/AIDS.

Researchers tracked 888 couples (mean age, 42 years) in which only one person was HIV-positive and that individual was taking suppressive antiretroviral therapy. The participants lived in 14 European countries and were followed for a median of slightly over a year between 2010 and 2014. About two-thirds of the couples were heterosexual and the rest were men who have sex with men (MSM).

The researchers found that 11 partners became infected with HIV — 10 MSM and one heterosexual. But the analysis of the virus in their bodies revealed that none were infected by their partners. Instead, they’d contracted HIV by having sex outside their relationships; 33 percent of HIV-negative MSM reported having condomless sex with other partners compared to 4 percent of heterosexuals.

While no one was infected with HIV by their partners, the researchers acknowledged that chance could have played a role in the findings and that there could be a small actual risk. But the researchers said it’s unlikely this risk is above 0.3 percent per year for heterosexual couples or 0.7 percent per year for MSM couples.

Several authors disclosed financial ties to the pharmaceutical industry.

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