By Jason Gale | Bloomberg
San Francisco reversed some of the highest rates of syphilis and chlamydia in the US after county health officials recommended a low-cost tablet taken like a “morning-after pill.”
Two analyses published this week confirm that the low-cost antibiotic doxycycline taken within 72 hours of unprotected sex can help drive down diseases linked to infertility, birth defects, and dementia.
The success in northern California, particularly among gay and bisexual men and transgender women, underscores the potential of so-called doxyPEP to address one of public health’s most urgent challenges. In 2023 alone, 3,882 babies in the US contracted syphilis from their mothers either in utero or during delivery — a tenfold increase since 2013.
“We have the evidence now to show that it does work,” said Michael Traeger, a research fellow at Boston’s Harvard Pilgrim Health Care Institute.
Traeger co-authored a study in JAMA Internal Medicine that found doxyPEP users in northern California experienced a 79% reduction in positive tests for chlamydia, 80% for syphilis, and 12% for gonorrhea after starting the regimen.
A separate study in the same journal, analyzing case reports from San Francisco, found a roughly 50% decline in early syphilis and chlamydia incidence 13 months after doxyPEP guidelines were introduced in October 2022, compared with expected numbers.
Still, that research found no improvement in gonorrhea cases among doxyPEP users, indicating that the antibiotic is less effective against the STI, possibly due to increasing rates of drug resistance.
The studies provide “welcome evidence” for the effectiveness of doxyPEP in preventing syphilis and chlamydia among an early-adopter group of men and transgender women, Jeanne Marrazzo, the director of the National Institute of Allergy and Infectious Diseases, and physician-scientist Jodie Dionne, wrote in an accompanying editorial.
“They also provide direction for the next generation of studies to address unanswered questions,” they said.
These questions include the long-term risks and benefits in other populations as well as the impact of doxyPEP on the worsening global antimicrobial resistance crisis.
For now, doctors have a new tool to help curb syphilis — a disease more frequently causing life-long, irreversible and potentially lethal damage to babies.
“We’re starting to see that perhaps this could actually turn the epidemic curve in many places,” Traeger said in an interview. “So I think, why wouldn’t we go for it?”
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