The early rollout of doxyPEP in San Francisco has contributed to a decline in sexually transmitted infections (STIs), according to reports at the Conference on Retroviruses and Opportunistic Infections. DoxyPEP refers to taking a single prophylactic dose of the antibiotic doxycycline within 72 hours after sex.

 

San Francisco was the first city to issue local doxyPEP guidelines in October 2022, and it is the first to see real-world outcomes. At the San Francisco AIDS Foundation’s Magnet clinic, 1,209 PrEP users, mostly gay and bisexual men, were prescribed doxyPEP through September 2023. STI incidence fell by 58% overall but more so for chlamydia (67%) and early syphilis (78%) than for gonorrhea (a nonsignificant 11% drop).

 

DoxyPEP is also having an impact at the local population level. More than 3,700 gay and bi men and transgender women started doxyPEP at Magnet and two other local clinics by the end of 2023. Chlamydia cases in this population decreased by 50% and early syphilis decreased by 51% relative to predicted levels. But again, there was no significant decline in gonorrhea.

 

These findings back up evidence from clinical trials showing that doxyPEP can reduce chlamydia and syphilis, though it is less effective against gonorrhea. “The evidence now overwhelmingly supports the use of doxyPEP for STI prevention, and we see benefits of an aggressive rollout to the populations who are most likely to benefit,” says San Francisco AIDS Foundation medical director Hyman Scott, MD, MPH.