Evidence of Biomedical STI Prevention Inadequate for Cisgender Women, Says NIAID Study

According to a Dec. 20, 2023 press release from NIH, certain prevention interventions for biomedical HIV and sexually transmitted infections (STI) – specifically doxycycline postexposure prophylaxis, or DoxyPEP – did not prevent STI acquisition in cisgender women, despite previously showing positive results in gay, bisexual, and other men who have sex with men and transgender women.

The study “found no significant reduction in STI incidence among those taking DoxyPEP compared to a control group.” This study, conducted among Kenyan cisgender women, stands in opposition to a similar study conducted in the U.S. among gay, bisexual, and other men who have sex with men and transgender women, which showed more effective results. Potential causes for the discrepancy posited by investigators include “low DoxyPEP use, high existing resistance to doxycycline among Neisseria gonorrhoeae bacteria, that cause gonorrhea, in the study location, and a local syphilis incidence too low to enable significant efficacy estimates.”

Jeanne Marrazzo, M.D., M.P.H., director of the National Institute of Allergy and Infectious Diseases (NIAID), itself a part of NIH, emphasizes the need for understanding “the biological and behavioral factors that influence STI acquisition in cisgender women, and to consider those factors when designing future biomedical prevention studies, rather than employing a ‘one-size-fits-all’ approach for all populations.” Dr. Marrazzo specifically highlights “insufficient evidence on how HIV and STI prophylaxis drugs perform in cervicovaginal versus rectal tissues.” She also singles out certain sociological factors that could play a part, calling for “studies [that] reflect cisgender women’s sexual activity preferences, as well as common power dynamics with sex partners.” She stresses the importance of “improving the efficacy and acceptability of biomedical prevention interventions among cisgender women” given “alarmingly high rates of congenital syphilis in the United States as well as steady HIV incidence and low HIV pre-exposure prophylaxis uptake among U.S. cisgender women.” NIH itself stresses its commitment to inclusive, diverse, and representative populations being covered by their clinical research.

NIH’s website has the full press release.