CDC suggests doxycycline postexposure prophylaxis for STI prevention

Doxycycline postexposure prophylaxis (doxy PEP) should be used in a comprehensive sexual health approach when offered, according to the Centers for Disease Control and Prevention (CDC).

An increase in sexually transmitted infection (STI) incidence has been observed over time in the United States, indicating a need for novel approaches to STI management. PEP, described as administration of a medication to prevent infection following exposure, is often used to prevent HIV and other infections.

Historically, doxycycline has been used to prevent infections such as malaria and Lyme disease, but recent recommendations from the CDC suggest using doxy PEP for STI prevention. Following 2021 recommendations, studies evaluating 200 mg doxycycline STI PEP found significant reductions in bacterial STI acquisition, leading to these updated guidelines.

A multidisciplinary work group of CDC staff with expertise in STIs and related factors created the guidelines. The impact of doxy PEP on bacterial STI incidence was determined through a systematic review of literature obtained from the Pubmed, MEDLINE, and Embase databases.

Eligibility criteria included being a randomized controlled trial, written in English, and assessing doxy PEP as STI prophylaxis. Strength of evidence was determined using the method employed by the US Department of Health and Human Service’s Panel on Antiretroviral Guidelines for Adults and Adolescents.

The risks and benefits of doxy PEP for STI prevention were also determined through a 2-day consultation conducted by the National Association of County and City Health Officials. The Doxy PEP Guidelines Development Workgroup reviewed the meeting report and reported findings that were consulted during development of the guidelines.

There were 4 studies included in the report. The first study assessed doxy PEP among 232 HIV-negative men who have sex with men (MSM) and transgender women (TGW) taking tenofovir disoproxil fumarate and emtricitabine.

Participants were randomized to take either 200 mg doxy PEP or no medication following anal or oral sex. The risks of chlamydia and syphilis infection were reduced by 70% and 73%, respectively, among the doxy PEP group. Rates of gonorrhea infections did not significantly differ between the 2 groups.

An additional study evaluating 501 MSM and TGW with HIV infection reported a significant reduction in chlamydia, gonorrhea, and syphilis incidence among participants taking oral doxycycline hyclate 200 mg preferably within 24 hours and no later than 72 hours after sex.

The third study in the report randomly assigned MSM to take doxy PEP within 24 to 72 hours of sex or no doxy and then vaccination with 4CMenB (Bexsero) or no vaccine. During a 96-week follow-up, an association was reported between doxy PEP and significantly reduced incidence of gonorrhea, chlamydia, and syphilis.

The final trial evaluated cisgender women assigned 1:1 to doxy PEP or standard care. While bacterial STI infection was not significantly reduced among doxy PEP patients, only 29% of these patients had detectable doxycycline, indicating a potential link between nonadherence and the lack of efficacy.

Adverse events reported following doxy PEP use included gastrointestinal side effects, a grade 2 laboratory abnormality, and 3 grade 3 adverse events. No severe adverse events were reported.

Following this data, the CDC stated doxy PEP is a feasible and acceptable intervention for preventing STIs, recommending a focused effort for implementation. The greatest benefits were found among gay, bisexual, and other MSM and TGW, and those with a history of at least 1 prior STI in the past 12 months.

Investigators also recommended providers use clinical judgement and shared decision-making when determining if doxy PEP is appropriate for use in patients not included in the CDC guidelines. Patients should self-administer a dose of 200 mg as soon as possible within 72 hours after oral, vaginal, or anal sex.

"I’m really impressed with how inclusive the CDC doxy PEP guidelines are," said Jenell Stewart, DO, MPH. "As new tools become available, it’s important to ensure that populations aren’t inadvertently being excluded because initial data are focused on people assigned male sex at birth who recently had an STI."

Reference

Bachmann LH, Barbee LA, Chan P, et al. CDC clinical guidelines on the use of doxycycline postexposure prophylaxis for bacterial sexually transmitted infection prevention, United States, 2024. MMWR Recomm Rep. 2024;73(No. RR-2):1–8. doi:10.15585/mmwr.rr7302a1