Population-Level Effect of DoxyPEP on Syphilis

Clinical Takeaway

: Syphilis diagnoses were dramatically reduced in Seattle, King County after DoxyPEP implementation, though congenital syphilis cases continued to rise.

Context

In the DoxyPEP clinical trial, doxycycline postexposure prophylaxis (DoxyPEP) was highly effective in reducing syphilis among men who have sex with men (MSM) and transgender women (TGW). This led to increased uptake in these high-risk groups in Seattle, King County (a DoxyPEP trial site) — and subsequent expansion of DoxyPEP access to other patients at risk. With several years of surveillance data now available in that county, researchers sought to quantify the population-level effect of DoxyPEP implementation on syphilis diagnoses. To do so, they compared the number of syphilis cases diagnosed after DoxyPEP implementation (March 2023–June 2025) with the expected number of cases had DoxyPEP not been implemented (based on pre-implemen…

Reviewing Author

Carlos del Rio, M.D.

Disclosures

Grant/Research SupportNIH/National Institute of Allergy and Infectious Diseases; NIH/National Institute on Drug Abuse

Editorial BoardsJAIDS: Journal of Acquired Immune Deficiency Syndromes; Vaccines

Leadership Positions in Professional SocietiesInternational Antiviral Society–USA (Board of Directors); Infectious Diseases Society of America (Past President)