After following nearly 900 heterosexual and gay couples for an average of 16 months, researchers found no evidence that uninfected partners became infected after condomless sex with an HIV-positive partner with viral suppression.
This good news bolsters the role of HIV treatment as a form of prevention, said lead author Dr. Alison Rodger, of the University College London.
"I think the big push now should be to expand testing, getting people diagnosed and get them on treatment," Rodger told Reuters Health.
Past studies have suggested that the risk of passing the virus to an HIV-negative person was low for people with low levels of HIV in their blood because of antiretroviral therapy (ART).