The herpes drug acyclovir doesn't reduce the risk of HIV infection, a new study says.
The five-year trial included more than 3,400 African couples in which one partner had HIV and one partner was HIV-free, Agence France Presse reported.
The infected partners were randomly selected to take twice-daily doses of acyclovir or a placebo.
During the study, there were 41 HIV infections among couples in which the infected partner took acyclovir, and 43 HIV infections among those who took a placebo. The researchers said this wasn't a significant difference, AFP reported.
The study appears online in the New England Journal of Medicine.