Presentation:
HIV is preventable with the use of daily oral PrEP or long-acting injectable PrEP for all populations regardless of sex or gender. Additionally, event-driven PrEP is an option for cisgender men who desire intermittent use of medications. The IPERGAY Trial provided an important answer, intermittent dosing of PrEP is an effective method to prevent HIV, and as the only randomized controlled trial of event-driven PrEP, we are left with a persistently unanswered question, does event-driven PrEP only work for cisgender men? Real-world data and observational studies in Paris, San Francisco, Bangkok, Johannesburg, Amsterdam, and Harlem suggest that event-driven PrEP is desired, effective, and cost-effective. Cisgender women in Southern and Eastern Africa have reported a preference for an HIV prevention method that did not require taking daily pills, which made event-driven dosing more user-friendly and acceptable. However, efficacy data on event-driven PrEP among cisgender women are lacking. Pharmacokinetic studies on drug levels in plasma, rectum, and genital samples from cisgender women, cisgender men, and transgender women suggest that drug levels are higher in the rectum than the vagina and lower in the presence of estrogen, and yet despite these differences across sex and gender, daily oral Tenofovir Disoproxil Fumarate-Emtricitabine is highly effective at preventing incident HIV in all populations. Are these differences in drug concentrations a valid justification limiting event-driven PrEP use to cisgender men who have sex with men? In many settings, cisgender women who are not interested in or have barriers to daily dosing, even in settings of infrequent sexual exposures, have been dissuaded from using oral PrEP due to concerns about the need for perfect adherence for vaginal protection. Seven doses of oral PrEP a week offers excellent protection against HIV and recent retrospective data demonstrated that four single strength doses a week had similarly high protection among cisgender women suggesting that dosing frequency needs may not differ by sex assigned at birth.