PHOTO AP VIA AAP/EDUARDO VERDUGO: Used with permission.

Professor Pietro Vernazza, President of the Swiss Federal AIDS Commission, which produced the controversial statement on the effect of treatment of HIV transmission earlier this year, made some qualifications to the statement on a panel of experts convened to discuss the topic prior to the IAS World AIDS Conference in Mexico City.

“We never thought of it as a statement that was to be delivered worldwide,” said Vernazza. “It was meant only to be delivered to Swiss physicians to help them discuss sexual risk- taking with their patients and steady partners.” He said that a steady partner was really the only one who could assess the risks of having unprotected sex– on their knowledge of how well their partner adhered to their antiretrovirals and how often they were monitoring their viral load.

Vernazza qualified the title of the Swiss Statement which read, “HIV-positive people with no other STIs and on effective antiviral therapy do not transmit HIV sexually”, saying that this was misleading in that it did not acknowledge a certain level of risk which was always present with unprotected sex with an HIV- positive partner. It was a matter of whether people thought that risk was in the comfortable range for normal life.

The motivation for the Swiss Statement was also political. Vernazza said that because it was possible for the Swiss state to prosecute HIV-positive people who had unprotected sex with consenting, fully-informed HIV-negative partners, the statement could also be used in court to show that if an individual was on successful treatment, they could not expose or transmit HIV. It was also made to help serodiscordant couples that wanted to have a baby without using the sperm- washing technique.

The relative risk of transmission on successful treatment quoted by the Swiss was 1:100,000. This figure was challenged by panel member Professor Myron Cohen of the University of North Carolina who said that the Swiss assumption that transmission was not possible below a certain viral threshold had been recently rejected by Australian experts. (Dr David Wilson of the University of New South Wales recently published a study in The Lancetthat used mathematical modelling to estimate the cumulative risk of transmission with a partner with a viral load of 10 copies per millilitre of blood. Although this showed the risk to be 0.43% from an HIV- positive male to HIV- negative female, the risk of male-to-male transmission through anal sex was estimated at 4.3% per year. It is important to state though that this is a mathematical projection and not the result of a clinical trial.) Vernazza claims these Australian studies are flawed.

Nikos Dedes, a community advocate from the European AIDS Action Group congratulated the Swiss team saying the report allowed the realisation “that we (HIV-positive people) will no longer consider ourselves a threat to others.” This statement will allow serodiscordant couples to have children, he said, help remove the fear of transmission through condom breakage, increase the likelihood of disclosure, reduce stigma and discrimination against HIV-positive people and allow them to “regain the right to the uninhibited experience of sexual pleasure.”

Community representatives at the meeting spoke fervently in support of Dedes’ speech, adding that a Mexico Manifesto was circulating at the Conference calling for “the representatives of science, medicine, economy, governments and WHO and UNAIDS to recognise the Swiss Statement and not to suppress information”. A final note of caution was introduced into question time about the need for more research into the lack of evidence around anal sex and transmission, given that the Swiss statement only used a cohort of heterosexuals.

During the Conference itself, Dr Susan Attia presented results of a survey of research into serodiscordant partners where one partner was undetectable (and without STIs) and concluded that, “the body of indirect evidence suggests that HIV transmission is very low or very rare.” Her team of reviewers was unable to conclusively support or deny the Swiss claims, she said.