Using data from the Partners PrEP Study , a randomized , placebo-controlled trial of daily oral tenofovir ( TDF ) and emtricitabine/tenofovir ( FTC/TDF ) PrEP among heterosexual HIV-@ serodiscordant couples from Kenya and Uganda , we assessed PrEP efficacy among subgroups at higher risk for HIV-@ acquisition , including subgroups of women with high HIV-@ incidence .