PrEP has been shown to help reduce HIV infection risk in multiple studies. The iPrEx trial showed that PrEP reduces the risk of HIV infection among gay and bisexual men and transgender women. Two large trials, Partners PrEP and TDF2, showed that PrEP also reduces the risk of HIV infection among heterosexual men and women. The Bangkok Tenofovir Study demonstrated that PrEP works for people who inject drugs.