Does Sex Have Impact on HIV Prevention Research?

March 2, 2015

This post was written by Morenike Folayan, Coordinator of the New HIV Vaccine and Microbicide Advocacy Society and member of the CROI Community Liaison Subcommittee.

At the CROI meeting, I seem to be getting signals that sex significantly impacts HIV research design, data interpretation and data use.

First, I learned that availability of tenofovir, the drug used for pre-exposure prophylaxis (PrEP), is 10 to 100 times lower in the vagina tissues than the rectal tissues when taken orally. This therefore implies that the results of PrEP studies conducted to assess HIV transmission through anal sex cannot be automatically translated to imply the results would be pan out the same way when considering vaginal sex. Hmmmm.

Second, I also learned, through informal conversation with those who work in the field for ARV studies, that the reasons many HIV positive men decide to commence ARV use for HIV prevention (treatment as prevention, or TasP) differ from the reasons why women do commence TasP. More men commence TasP out of a sense of protection of their sexual partner—they have a higher sense of responsibility to protect their sexual partner from getting infected. Women on the other hand, commence the use of TasP simply because they are eligible to use the product. I found that very interesting. I think there may be cultural differences in this observation. I doubt if this is the case in Africa. However, like the lessons we learn from CROI, we need evidence. I would like to see a formal study evaluate this social context of TasP use by men and women in different cultural setting.

Third, the iPrEx OLE study showed increase uptake of, and adherence to, PrEP by MSM who were at high risk for HIV infection. In the VOICE study, we see less uptake and adherence by women who were at high risk of HIV infection. Hmmm. Are we starting to see differences in cultural perception of risk or is this truly a sex difference in risk perception?

(Editor’s note: In iPrEx OLE, participants knew that they were being offered an effective prevention tool—it was an open label study; in VOICE, women were counseled that they might be receiving a placebo and that none of the strategies were proven. Understanding how context—research site, clinic, public health program or community center—affects uptake and risk perception is also key.)

Reason for more studies on sex differences in PrEP and TasP use. Maybe conducting studies with transgenders may help address this question. Maybe.