Combined Antiretroviral Treatment and Heterosexual Transmission of HIV-1: Cross Sectional and Prospective Cohort Study, Jorge Del Romero et al., British Medical Journal (2010)

This study concluded that there is a significant impact of combined antiretroviral treatment on the rate of HIV transmission in heterosexual HIV-discordant couples. The study, which took place in Spain, found that of the 476 couples where the HIV positive individual was not on combined antiretroviral therapy there was a serotransmission rate of 9.2%. In the 149 couples where the HIV positive partner was taking such treatment, no serotransmissions occurred. The 625 couples were in monogamous, heterosexual relationships with no reported outside risk behavior.

Of the couples where the HIV positive individual was not on combined antiretroviral treatment, 194 reported always using condoms for all sex acts. Consistent condom use lowered the transmission rate of 9.2% by about 93% and, among these couples, only one serotransmission occurred. No serotransmissions occurred in the 149 couples where the HIV-positive partner was on combined antiretroviral treatment. While the results should not be read to imply that it is impossible for such transmission to occur, it does suggest that combined antiretroviral treatment can significantly lower the rate of transmission in discordant couples.