The administration of doxycycline (doxyPEP) after sexual intercourse could halt the rampant course of syphilis and chlamydia infections, as reported by the competent surveillance networks in recent years. According to a publication in JAMA Internal Medicine on data from programs providing prophylactic treatment to specific population groups, the reduction in these sexually transmitted diseases was steep, reaching up to 80%.
doxyPEP is a new strategy for the prevention of sexually transmitted diseases (STDs) that involves taking a single dose of doxycycline, a common and well-tolerated antibiotic, within 72 hours of sexual intercourse. Clinical trials have shown that administering doxyPEP to men significantly reduces the risk of bacterial STIs—particularly chlamydia and Treponema pallidum, the bacterium that causes syphilis. However, few studies have evaluated the effectiveness of antibiotic treatment as part of a prevention program.
“Interventions that are effective in clinical trials do not always translate to success in real-world settings, where people often have a harder time adhering to their medications,” said study leader Michael Traeger, Ph.D., a researcher at the Harvard Pilgrim Institute for Health Care, who collaborated with researchers from three parts of the Kaiser Permanente health system in the U.S. (Northern California, Mid-Atlantic States, Georgia). “We were excited to see that doxyPEP users in our study experienced reductions in chlamydia and syphilis infections comparable to those seen in clinical trials.”
Up to 80% Protection
It began in October 2022 in San Francisco, where a task force was formed and guidelines were issued for the administration of doxyPEP to high-risk groups for STIs (gay-bisexual men, trans women). Kaiser Permanente of North Carolina began administering doxyPEP to people already taking HIV prophylaxis (PrEP) a month later, in November 2022.
The new study, which examined the largest cohort of doxyPEP recipients reported worldwide to date, used pharmacy data to identify HIV-PrEP users at Kaiser Permanente who filled prescriptions for doxyPEP. Of the nearly 12,000 HIV-PrEP users, nearly one in five (2,253 people, mostly male at birth) received doxyPEP within the first year of its availability.
Then, they looked at STD test results before and after starting doxyPEP, and they found significant drops of 79% for chlamydia and 80% for syphilis, but only 12% for gonorrhea.
Concerns about gonorrhea and antimicrobial resistance
By giving patients doxyPEP, doctors saw a significant reduction in both positive STD tests and the number of patients needing treatment after exposure to an STD. But the reduction in gonorrhea in the study was modest, highlighting the need for regular STD screening in patients taking doxyPEP.
Rising rates of syphilis, including more cases of congenital syphilis, highlight the urgent need for innovative tools like doxyPEP
There are important questions that still need to be answered about doxyPEP, including its impact on antimicrobial resistance, suggesting that their study shows that wider implementation of doxyPEP could have enormous benefits in reducing the spread of STIs and improving sexual health.
