Research is suggesting with increasing clarity and certainty that successful antiretroviral (ARV) treatment is a highly effective means of preventing HIV.

Treatment as prevention (TasP) got a boost earlier this year when England’s Expert Advisory Groupon AIDS (EAGA) and the British HIV Association (BHIVA) published a position paper calling vaginal transmission risk “extremely low” when the HIV-positive partner maintains an undetectable viral load and both partners are free of sexually transmitted infections. The paper’s authors anticipate a similar extremely low risk of transmission during unprotected anal sex when the above conditions are met.

A report presented at the Third International Workshop on HIVand Women in Toronto that pooled data from six different studies—including the famed HPTN 052 trial—provided further proof of TasP’s success.

In contrast to the tightly controlled HPTN 052 trial, a new study of heterosexual straight couples in Uganda supplied proof of TasP in a real world setting. The researchers found that none of the people living with HIV transmitted to their partners if they were taking ARVs, compared with a considerable number of those off therapy who did.

Gus Cairns, the patient representative on the executive committee of the BHIVA, calls the current flow of research on TasP “overdue” and hails ARVs as “considerably more effective than any other prevention modality.”