Appendix: the Swiss Statement

In January 2008, a statement for doctors in Switzerland was published on the safety of HIV treatment to reduce transmission. [1]

The main statement was an HIV positive person on effective HIV treatment (ART) cannot transmit HIV through sexual contact.

One reason it was produced was to support serodifferent heterosexual couples to be able to have children naturally without facing legal charges. A serodifferent couple is where one partner is HIV postive and the other is HIV negative.

Several conditions were included for the statement.

  • The HIV positive person needs to be good at taking their meds and routinely seeing their doctor; and
  • Their viral load needs to be undetectable for at least six months (for example, less than 40 copies/mL); and
  • That they have no other sexually transmitted infections (STIs).

Although scientifically no risk can ever technically be zero and there was little evidence to prove the statement – this risk was compared to the risk of transmitting HIV from kissing,

The document also said use of sperm washing was no longer needed if the man was positive and on effective ART.

Since 2008, several important studies have produced evidence that support the Swiss Statement.

  • In 2011, the HPTN-052 study reported that ART dramatically reduced the risk of HIV transmission in sero-different heterosexual couples. The study was so effective that it was stopped early so all participants could use ART. The single transmission was in a couple where the positive partner had just started treatment. This meant viral load would not have been undetectable. [2]
  • In 2014, the PARTNER study reported no HIV transmission after serodifferent couples had sex without condoms more than 44,000 times. [3]
  • In 2016, the publication of the final results of the PARTNER study reported no transmissions after more than 58,000 times that couples had sex without condoms. [4, 5]
  • Also in 2016, HPTN-052 reported that the early protection reported see when the study was changed, continued for years afterwards.

The results is that while the Swiss Statement was controversial when first published, it is now established as an effective was to protect again HIV transmission. Also, any risk that might exist is so small that national health guidelines call this risk negligible

Together this evidence should:

  • Stop legal cases where HIV positive people are criminalised for consensual sex.
  • Enable serodifferent couple to have children without the worry of HIV.
  • Help HIV positive people develop relationships without the fear of infecting their partners.
  • Enable HIV negative people to stop worrying about HIV if their partner is HIV positive and on effective ART.

The Swiss Statement started as an initiative to protect HIV positive people in Switzerland. It has since became a leading document that improved the quality of life for millions of people living with HIV and their partners.


  1. Vernazza P et al. HIV-positive individuals not suffering from any other STD and adhering to an effective antiretroviral treatment do not transmit HIV sexually. (Les personnes séropositives ne souffrant d’aucune autre MST et suivant un traitment antirétroviral efficace ne transmettent pas le VIH par voie sexuelle). Bulletin des médecins suisses 89 (5), 30 January 2008. Included with English translation.
    Swiss Statement: English translation and original French publication  (PDF)
  2. Treatment is prevention: ARV treatment in HPTN-052 reduces transmission by at least 96%: single transmission in treatment arm occurred prior to viral suppression. HTB report, August 2011.
  3. No HIV transmissions with undetectable viral load: interim PARTNER study results show need for longer follow-up. HTB report March 2014.
  4. ZERO: no linked HIV transmissions in PARTNER study after couples had sex 58,000 times without condoms.
  5. Q&A on the PARTNER study: how to interpret the zero transmission results

Note: The factsheet was first published in 2008 but was last updated in October 2016.

Last updated: 1 April 2019.