Can a pill and a vaccine stop STIs in High-Risk men?

NCT ID NCT04597424

Completed Prevention Sponsor: ANRS, Emerging Infectious Diseases Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study tested two strategies to prevent sexually transmitted infections (STIs) in men who have sex with men and already take HIV PrEP. One group took doxycycline pills after unprotected sex, and another group received a meningitis vaccine (Bexsero). The goal was to see if these approaches could reduce new cases of chlamydia, syphilis, and gonorrhea. Over 550 men took part in this completed Phase 3 trial.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: doxycycline and Bexsero® vaccine
What this could lead to: If it works, this could offer a new way to prevent bacterial STIs in high-risk groups, reducing infections like chlamydia, syphilis, and gonorrhea.
What could go wrong: This is a completed Phase 3 trial, but results may not apply to all populations. Doxycycline overuse could lead to antibiotic resistance, and the vaccine may not protect against all gonorrhea strains.

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Conditions

The condition(s) this trial relates to.

Risk-Taking Unsafe Sex bacterial sexually transmitted disease prevention target HIV infectious disease prevention target meningococcal infection prevention target

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

RISK-TAKING UNSAFE SEX

Contacts and locations

Locations

Hôpital Bichat

Paris, 75000, France
Hôpital Européen Georges Pompidou

Paris, 75908, France
Hôpital Hôtel Dieu

Paris, 75181, France
Hôpital Necker-Enfants Malades

Paris, 75743, France
Hôpital Pitié-Salpétrière

Paris, 75651, France
Hôpital Saint-Antoine

Paris, 75571, France
Hôpital Saint-Louis

Paris, 75475, France
Hôpital Tenon

Paris, 75970, France
Hôpital pitié Salpetrière

Paris, 75651, France

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