Abstract Body


Sexually transmitted infections (STIs) have been on the rise in the United States over the past decade and disproportionately impact men who have sex with men and transgender women. The San Francisco Department of Public Health (SFDPH) issued guidance in October 2022 recommending clinicians to prescribe doxy-prophylaxis as an STI prevention strategy to cis men and trans women who report condomless sex with a cis male or trans female partner and have had a bacterial STI in the past year. We assessed the trends of male rectal chlamydia, male rectal gonorrhea, and adult male syphilis cases to explore the association between the doxy-prophylaxis policy and bacterial STI rates among males in San Francisco.


We reviewed publicly available monthly STI reports on male rectal chlamydia, male rectal gonorrhea, and adult male syphilis between April 2020 and July 2023. The mean difference of the number of monthly STI cases from 12 months before vs. 8 months after the policy and 95% confidence intervals were calculated. We conducted a segmented linear regression analysis of the trends for each STI. To account for temporal trends related to COVID-19, we included two breakpoints, November 2021 (period of Omicron) and November 2022 (period of policy introduction). We compared the slopes of the fitted regression lines before and after. Two-sided P<0.05 was considered statistically significant. All statistics were performed in R version 4.3.1.


The mean monthly difference before vs. after the doxy-prophylaxis policy for male rectal chlamydia cases was a decrease of 24 cases per month (95% CI: -2 to 51), the difference for male rectal gonorrhea was a decrease of 32 cases per month (95% CI: 9 to 55), and the difference for adult male syphilis was a decrease of 31 cases per month (95% CI: 20 to 42). Before the policy recommendation, male rectal chlamydia cases increased by 0.7 per month (95% CI: -1.2 to 2.6) and after decreased by 9.1 per month (95% CI: -13 to -5.3) (p<0.001). Male rectal gonorrhea cases decreased by 3.7 per month before the policy and decreased by 3.7 cases per month after (p=0.994). Adult male syphilis cases decreased by 2.6 cases per month before the policy and decreased by 3.0 per month after (p=0.843).


The SFDPH doxy-prophylaxis recommendation was associated with a significant decrease in male rectal chlamydia and continued decline in male rectal gonorrhea and syphilis. Given the ecologic nature of the study, further confirmation is needed.