A report suggesting that it is safe for some individuals infected with HIV to have sex without a condom has sparked controversy and concern among scientists. The conclusions of the report from Switzerland's National AIDS Commission, published in the Bulletin of Swiss Medicine in late January, fly in the face of the decades-old HIV prevention message to always use barrier protection.

The Swiss researchers reanalyzed data from previous studies and concluded that sex without a condom is safe under specific conditions, such as when the infected person is in a long-term, monogamous relationship, has had undetectable levels of the virus for at least six months and complies with a strict antiretroviral medication program. They stressed, however, that the finding does not apply to all HIV-infected individuals on medication and that such sex requires the informed consent of the infected person's partner.

Myron Cohen, director of the University of North Carolina's Center for Infectious Diseases in Chapel Hill, points out that although the risk of transmitting the virus to an uninfected partner decreases under the conditions of the Swiss study, it does not disappear entirely. “We have an HIV epidemic,” explains Cohen, “and suggesting that some people with HIV can have sex without a condom will only create confusion and make it worse.”

But the debate is set to continue. Another study released in early February found that macaques on antiretroviral medications don't acquire the simian version of HIV when exposed (PLoS Med. 5, e30; 2008).

The result supports the idea that taking a combination of antiretroviral medicines could slow or prevent HIV transmission in humans, although follow-up research is needed.