Why is adherence to antiretroviral therapy particularly critical in reducing HIV transmission?

• A. Viral suppression reduces sexual transmission risk; undetectable equals untransmittable (U=U).
• B. Adherence has no effect on transmission.
• C. Condom use alone is sufficient; ART is irrelevant.
• D. Transmission risk is fixed regardless of ART.

Answer: (A)

Adherence to ART is essential because it lowers the HIV viral load to undetectable levels in blood and genital secretions. When viral load remains undetectable, the risk of sexual transmission becomes effectively zero, a concept summarized as U=U (undetectable equals untransmittable). Maintaining consistent adherence keeps this suppression, so the chance of transmitting HIV during sex is dramatically reduced. If adherence falters and viral load rebounds, the infectiousness rises again, increasing the possibility of transmission. While condom use provides protection, ART adherence is the key factor in preventing sexual transmission once suppression is achieved.