Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP) protects transgender women against HIV if they take it consistently, HIVandHepatitis.com reports. Publishing their findings in The Lancet, researchers analyzed data from the global iPrEx trial and its open-label extension (OLE), looking more closely at PrEP effectiveness among trans women.

IPrEx, which included 2,499 participants randomized to receive daily PrEP or a placebo, first proved PrEP’s effectiveness among men who have sex with men (MSM) in 2010. The OLE trial results were published in 2014.

Of the iPrEx participants,  339 (14 percent) were classified as trans women: 29 (1 percent) who identified as women, 296 (12 percent) who identified as trans, and 14 (1 percent) who identified as men and reported using female hormones. Out of those 339, 192 participated in the OLE phase of the trial, with 79 percent of them choosing to take Truvada (they could take Truvada or simply continue being observed for the trial without taking the drug).

Trans women were more likely than MSM to report sex work or transactional sex (64 percent vs. 38 percent), condomless receptive anal intercourse (86 percent vs. 55 percent), sexually transmitted infections during the previous six months (38 percent vs. 24 percent) and more than five sexual partners during the past three months.

While MSM were more likely to adhere to PrEP if they were at higher risk for HIV—reporting more condomless anal sex partners—the opposite tended to be true for trans women.

There were 11 new cases of HIV among the trans women in the PrEP group and 10 in the placebo group. so being assigned to one group or the other essentially had no bearing on whether they contracted the virus. (Two trans women became HIV positive during the OLE phase of the trial.) However, none of the 11 had detectable drug in their systems when they seroconverted.

HIV incidence was zero if the trans women had detectable drug and 4.9 percent per year if they had no detectable drug, compared with a respective 0.4 percent and 2.8 percent among MSM.

Trans women in the OLE phase had drug levels indicating they were taking four or more tablets of Truvada per week 18 percent of the time, compared with 36 percent of the time among the MSM participants. Trans women who took female hormones were more likely to have detectable or protective drug levels.

To read the HIVandHepatitis article, click here.

To read the study abstract, click here.