U=U — SCE Infectious Diseases MCQ

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EasyHIV MedicineU=USCE Infectious Diseases

A 30-year-old man with HIV (CD4 650, VL <50 on ART for 5 years) asks whether he can transmit HIV through unprotected sexual intercourse. His viral load has been consistently undetectable for 4 years. What is the current evidence-based answer?

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Correct answer: E — Undetectable = Untransmittable (U=U); there is effectively zero risk of sexual transmission with sustained undetectable viral load

The PARTNER 1 and PARTNER 2 studies demonstrated zero linked HIV transmissions among serodifferent couples (including MSM) where the HIV-positive partner had a sustained undetectable viral load (<200 copies/mL), over thousands of acts of condomless sex. U=U (Undetectable = Untransmittable) is endorsed by BHIVA, WHO, UNAIDS, and all major HIV organisations. This applies to all types of sexual intercourse. Communicating U=U is an important part of HIV clinical care.

Reference: BHIVA 2025 – ART guidelines; PARTNER 2 Study 2019 – Lancet