A single dose of doxycycline, a extensively used antibiotic, taken after intercourse halved the incidence of chlamydia and early syphilis amongst homosexual and bisexual males and transgender girls in San Francisco, metropolis well being officers introduced on Monday. The findings provided a glimmer of hope amid a rising tide of sexually transmitted infections nationwide.
The technique is known as doxy-PEP, shorthand for doxycycline post-exposure prophylaxis. In San Francisco, homosexual and bisexual males and transgender girls who had a historical past of S.T.I.s or a number of intercourse companions got a provide of the antibiotic and requested to take two 100-milligram tablets inside 72 hours of unprotected intercourse.
New instances of chlamydia and early syphilis — however not gonorrhea — dropped over the course of a couple of 12 months. The outcomes had been introduced on the Convention on Retroviruses and Opportunistic Infections in Denver.
“It’s not delicate, it is vitally quick and we’re seeing the start of it, not the tip,” Dr. Hyman Scott, a medical director on the San Francisco Division of Public Well being, mentioned in an interview. “That is what we wish for S.T.I. prevention.”
Methods to stem S.T.I.s are sorely wanted.
Syphilis, as soon as almost eradicated in america, has reached the very best fee of latest infections recorded since 1950, the Facilities for Illness Management and Prevention reported in January. Left untreated, syphilis can harm the center and mind and trigger blindness, deafness and paralysis.
Charges of chlamydia remained flat nationwide in 2022, in contrast with the quantity in 2021, however at almost 1.7 million instances, infections had been frequent. (Gonorrhea instances decreased in 2022, however specialists cautioned that the development may need been the results of a lower in testing.)
“These knowledge are merely taking a look at numbers of S.T.I. instances at completely different time factors however make me really feel hopeful that doxy-PEP might be able to scale back S.T.I.s at a inhabitants stage,” Dr. Ina Park, an S.T.I. skilled on the College of California, San Francisco, mentioned of the brand new outcomes. She was not concerned with the work.
The proof thus far helps the case for doxycycline use solely in homosexual and bisexual males and transgender girls. Earlier research have proven {that a} single dose of doxycycline taken inside 72 hours of unprotected intercourse considerably cuts the chance of S.T.I.s in these teams.
“Nearly all of S.T.I.s in america happen in cisgender girls,” mentioned Dr. Jonathan Mermin, director of the Nationwide Middle for H.I.V., Viral Hepatitis, S.T.D. and TB Prevention on the C.D.C.
“Research of whether or not doxy-PEP works in cisgender girls needs to be applied as shortly as doable,” he mentioned.
In October, the C.D.C. launched draft tips for doxy-PEP. It can subject its remaining suggestions within the subsequent few months, Dr. Mermin mentioned.
However, prompted by early scientific trial outcomes, the San Francisco Division of Public Well being — a pioneer within the battle in opposition to H.I.V. and S.T.I.s — started recommending doxy-PEP a 12 months earlier than the company’s draft tips had been revealed.
Metropolis officers tracked month-to-month charges of chlamydia, gonorrhea and early syphilis earlier than and after the introduction of doxy-PEP in November 2022. In addition they in contrast the numbers with the speed of infections in cisgender girls.
Over a 13-month interval, new instances of chlamydia and early syphilis throughout the town dropped by 50 %, in contrast with the anticipated numbers. Charges of gonorrhea didn’t change considerably.
Against this, instances of chlamydia in cisgender girls steadily elevated. Metropolis well being officers plan to investigate the numbers over an extended interval to substantiate the downward development.
“The truth that we didn’t see declines in S.T.I.s in different populations not advisable for doxy, particularly cis girls, strengthens the conclusion that the decline in chlamydia and early syphilis instances is expounded to doxy-PEP rollout,” mentioned Madeline Sankaran, an epidemiologist on the San Francisco Division of Public Well being who introduced the findings.
A separate examine discovered that S.T.I. charges dropped regardless of a rise in sexual companions, situations of intercourse with out condoms and group intercourse amongst individuals taking doxy-PEP. Greater than 75 % of these provided the tablets reported taking them after intercourse with out condoms, the researchers mentioned.
Whereas the outcomes are promising, Dr. Mermin cautioned, they might have been skewed by the 2022 outbreak of mpox, beforehand referred to as monkeypox, throughout which high-risk teams voluntarily curtailed their sexual exercise. There was additionally a restricted impact on charges of gonorrhea, he added.
Dr. Mermin mentioned reducing S.T.I.s nationwide would require guaranteeing that the method is used within the South and in rural areas, and in Black and Latino populations which might be at excessive threat.
“No software, regardless of how highly effective, will stop infections if it doesn’t attain the individuals who want it most,” he mentioned.
There was some concern concerning the emergence of antibiotic resistance with widespread use of doxycycline, however the restricted knowledge out there counsel that the method doesn’t considerably enhance resistance in individuals who take it, Dr. Mermin mentioned. The C.D.C. and others are monitoring the developments, he added.
If additional evaluation confirms doxy-PEP’s potential, Dr. Park mentioned, she might foresee intercourse social gathering hosts providing the tablets, a lot as clinics now supply condoms.
Maybe the antibiotics can be in a jar with an indication saying, “Take two in your means out the door,” she mentioned. “That’s the place I see this going.”
