Doxycycline Postexposure Prophylaxis and Sexually Transmitted Infection Trends

Area of Science:

• Public Health
• Infectious Diseases
• Epidemiology

Background:

• Rising sexually transmitted infections (STIs) correlate with increased severe illness.
• Doxycycline postexposure prophylaxis (doxyPEP) is effective in trials but population-level impact is unknown.

Purpose of the Study:

• To evaluate the association between citywide doxyPEP guideline release and STI incidence in San Francisco.
• Focus on chlamydia, gonorrhea, and early syphilis among men who have sex with men (MSM) and transgender women.

Main Methods:

• Population-level interrupted time series analysis of monthly STI cases.
• Comparison of cases before (July 2021-Oct 2022) and after (Nov 2022-Nov 2023) guideline release.
• Inclusion of all reported chlamydia, gonorrhea, and early syphilis cases in MSM and transgender women.

Main Results:

• Chlamydia and early syphilis cases significantly decreased post-doxyPEP implementation compared to projections.
• Chlamydia cases dropped by 49.64% and early syphilis by 51.39% over 13 months.
• A significant increase in monthly gonorrhea cases was observed post-doxyPEP.

Conclusions:

• San Francisco's doxyPEP guidelines correlated with reduced chlamydia and early syphilis but not gonorrhea.
• Sustained impact and potential adverse effects like antimicrobial resistance require further study.
• DoxyPEP implementation could significantly impact the national STI epidemic.