On August 26, 2026, POZ reported on two new real-world analyses of doxyPEP — a single dose of doxycycline taken within 72 hours after sex — presented at the 26th International AIDS Conference (AIDS 2026). The headline: the dramatic chlamydia and syphilis reductions seen in the pivotal trial are holding up outside of it, in the US Southeast and at national scale in Australia. The asterisk, again, is gonorrhea.

Why It Matters

DoxyPEP is now the most consequential thing to happen to STI prevention since PrEP, and it is running well ahead of the guidelines that govern who gets offered it. The Duke finding — two-thirds of benefiting patients would have been screened out by current eligibility criteria — is an actionable gap for the at-home testing and telehealth PrEP platforms (Nurx, Everlywell, myLAB Box, and the STI arms of the large men's health players) that increasingly serve as the front door to sexual healthcare. Eligibility rules written around trial populations are leaving measurable prevention on the table in high-incidence regions. For the diagnostics side, the gonorrhea divergence is the commercial signal. If doxyPEP reliably clears chlamydia and syphilis from a population but leaves gonorrhea flat or rising, the testing mix shifts: gonorrhea-specific, resistance-aware assays become the growth product, and multiplex panels need to report resistance markers rather than just presence. That is precisely the design brief behind Readily Diagnostics' Gates-funded point-of-care test covered earlier this month, which builds antibiotic-resistance detection for gonorrhea into the platform from the start. The broader lesson is one the sexual-health field keeps relearning: prevention tools do not distribute their benefits evenly, either across pathogens or across populations. The doxyPEP evidence base remains overwhelmingly built on gay and bisexual men and transgender women, with women of reproductive age still largely outside both the trials and the guidelines — a gap that looks increasingly conspicuous next to rising syphilis rates in that group.

The North Carolina analysis, led by Emily Niehaus, MD, PhD, of Duke University, looked at Duke HIV clinic patients prescribed doxyPEP between January 2022 and December 2025. The cohort was 95% men who have sex with men, roughly 2% transgender women; half Black, 40% white, 11% Latino, median age 36. Just over half were living with HIV and the rest were on PrEP. Overall STI incidence fell 67%, from 57 to 19 cases per 100 person-years. Chlamydia dropped from 21 to 4 per 100 person-years and syphilis from 10 to 2. Gonorrhea fell too, but only by half — 26 to 13. Longitudinal trend analysis showed an 81% reduction in chlamydia incidence and a 50% reduction in gonorrhea incidence after rollout.

The most useful finding for anyone building sexual-health services is about eligibility, not efficacy. Nearly two-thirds of people in the Duke analysis would not have qualified for doxyPEP under most current guidelines, because they had not had a bacterial STI in the prior year — and they saw similar reductions anyway. "This finding suggests that doxyPEP may provide benefit across a broader range of risk profiles than those represented in the original clinical trials, perhaps especially in high incidence areas like the southeast United States," Niehaus said. That is a direct argument for widening the eligibility funnel that telehealth STI platforms currently screen against.

Australia supplies the population-level read. Michael Traeger, PhD, of the Burnet Institute in Melbourne and colleagues conducted the first national analysis, using the ACCESS clinic network across 29 sites: 78,560 gay and bisexual men aged 16+ with at least one STI test, 27,725 with at least one diagnosis, spanning 5,198 syphilis, 27,190 chlamydia and 27,301 gonorrhea cases. Comparing pre-guidance (January 2022–April 2023) to post-guidance (October 2023–October 2025), the team estimated 2,973 fewer syphilis diagnoses than the prior trend predicted — a 55% reduction — and 7,604 fewer chlamydia diagnoses, a 36% reduction. Traeger suggested syphilis declined earlier than chlamydia partly through a "treatment as prevention" effect, with prompt therapy limiting onward transmission. Gonorrhea went the other way: 1,556 more cases than expected, an 11% increase that was not statistically significant.

That regional variation has a plausible mechanism. Comparing studies to date, differences in doxyPEP's effect on gonorrhea likely track pre-existing resistance to doxycycline and related antibiotics, which is rising worldwide — the pivotal San Francisco/Seattle trial saw a 55% gonorrhea reduction, French trials saw none, and Australia now looks closer to France. Some experts worry widespread doxyPEP use may itself contribute to resistance. Late in 2025 the FDA approved two new gonorrhea antibiotics, zoliflodacin (Nuzolvence) and gepotidacin (Blujepa), which could eventually deliver their own treatment-as-prevention effect.

Sources

Update — 2026-08-31

{Initial entry — story first created.}