The research involving couples in Kenya, Uganda and Botswana found that daily AIDS drugs reduced infection rates by an average of at least 62 percent when compared with placebo.

“Effective new HIV prevention tools are urgently needed and these studies could have enormous impact in preventing heterosexual transmission,” Margaret Chan, director-general of the World Health Organization (WHO), said in a statement.

She said the United Nations health agency would now work with countries to use the new findings to implement better protection strategies.