The Swiss Statement and Its Repercussions

There is evidence of some groups of gay men knowing, from the late 1990s onwards, that people with an undetectable HIV viral load were much less infectious, and were using this knowledge in sexual decision-making. Public discussion of this became much more high profile after a paper was issued by the Swiss Federal Commission for HIV/AIDS in January 2008.

The authors of the Swiss Statement have since said that they were surprised at the amount of attention their paper got and the global discussion it set off. It was intended purely as an incountry guideline directed at doctors and, significantly, at legal professionals. Much of the motivation for the statement lay in the fact that Switzerland had prosecuted and convicted a number of HIV+ people for exposing partners to HIV, and the doctors wanted there to be a statement saying that HIV+ people posed no risk to their partners if they were undetectable on stable antiretroviral therapy. They stated that unprotected sex between a positive person on antiretroviral treatment, and without an STI, and an HIV-negative person did not comply with the criteria for an "attempt at propagation of a dangerous disease" in the Swiss penal code nor for "an attempt to engender grievous bodily harm".

Although the statement purely concerns the position of individuals and was not connected with the mathematical-modelling studies that were starting to be issued which looked at the possibility of using viral control as a prevention measure, it was significant because it transformed the discussion around viral undetectability and infectiousness from one in which using viral load status to inform sexual-risk decisions was seen as dangerous, and a rationalisation for having unprotected sex, to one in which it became possible to talk about its legitimate use as a prevention measure.

Nonetheless, the statement caused widespread concern amongst some prevention and public health advocates who felt it was based on weak evidence in some areas and risked undermining people's efforts to maintain and promote condom-based safer sex.

The statement said that people with HIV are not sexually infectious ("ne transmettent pas le VIH par voie sexuelle"), as long as the following conditions are met:

• The HIV+ individual takes antiretroviral therapy consistently and as prescribed and is regularly followed by his/her doctor.
• Viral load is 'undetectable' and has been so for at least six months.
• The HIV+ individual does not have any STIs.