While the chance is slim, HIV-positive heterosexuals who have been taking antiretrovirals (ARVs) longer than six months and who are in regular care still may transmit the virus to their partners. French researchers reviewed studies of 1,672 straight couples of mixed HIV status in which the partner with HIV was taking ARVs longer than half a year. They found that between 70 percent and 100 percent of the HIV-positive partners were virally suppressed, and that the couples nixed condoms 17 percent of the time. There was one incident of a proven transmission, occurring before the HIV-positive partner had been treated for a year, although it was unclear if the transmission took place before or after six months. Because of this uncertainty, the researchers made two calculations about the risk for HIV transmission. They projected that out of 100,000 sex acts, the risk ranged between either zero and 8.7 (if that one transmission took place before six months of ARVs) or zero and 13 (if it took place after).