AO ("Alles Ohne") or BB (Bareback) refers to sex without a condom. In Switzerland, AO is openly advertised by some sex workers (often on escort sites), but is strongly discouraged by reputable professionals and all counseling centers:
- HIV: without a condom, depending on the practice, 0.04–1.4% risk of transmission per act
- Gonorrhea / Chlamydia / Syphilis: 30–90% risk in each case with a single contact with an infected person
- Hepatitis B/C: significantly higher risk with acts involving blood
Stealthing (secretly removing a condom) has been a criminal offense since 2024 — see Stealthing. Anyone offering anal sex should undergo comprehensive screening at least monthly, take PrEP, and ensure they have U=U status (undetectable HIV).