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Unsafe SexPhase 3DOXYVACNCT04597424

Combined Prevention of Sexually Transmitted Infections (STIs) in Men Who Have Sex With Men and Using Oral Tenofovir Disoproxil Fumarate/ Emtricitabine (TDF/FTC) for HIV Pre-Exposure Prophylaxis (PrEP)

A Phase 3 study testing Experimental: doxycycline and Bexsero® vaccine in people with Unsafe Sex and Risk-Taking, run by ANRS, Emerging Infectious Diseases at 9 sites in France.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

The study ANRS 174 Doxyvac is a clinical trial that will use Combined Prevention of Sexually Transmitted Infections (STIs) in Men Who Have Sex with Men and using oral TDF/FTC for HIV Pre-Exposure Prophylaxis (PrEP) and vaccination with Bexsero. Read more about this study

Who is it for?
Ages 18 years and older, men onlyHealthy volunteers can take part
Conditions the study is for
Unsafe Sex, Risk-Taking
What is being tested?
Experimental: doxycycline and Bexsero® vaccine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
556 participants
Where
9 sitesFrance
Study dates
19 Jan 2021to 19 Apr 2024
Phase
Phase 3
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • Men only
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Mens who have sex with mens (MSM) enrolled in the ANRS PREVENIR study.
  • At least 6-month experience with PrEP (within the ANRS PREVENIR study or before starting the ANRS PREVENIR study).
  • No clinical manifestation of primary HIV infection and no symptom of bacterial STI (chlamydia, gonorrhea, M. genitalium or syphilis).
  • History of documented bacterial STI with at least one episode in the last 12 months.
  • Participants who agree to sign the information and consent form specific to this study.
  • Valid health insurance (State medical aid (AME) is not health insurance).

Who cannot join

  • Syphilis diagnosed prior to inclusion without serologic evidence of cure (cure is defined as decreased by at least 4-fold of the non-treponemal antibody titer [Venereal Disease Research Laboratory (VDRL), Rapid Plasma Reagin (RPR)] relative to the titer at initiation of treatment of syphilis).
  • HIV infection.
  • Previous vaccination with Bexsero® or any other meningococcal B vaccine.
  • Vaccination during the 4 weeks (28 days) preceding the first vaccination of the study.
  • Previous vaccination with an experimental vaccine in the previous 5 years.
  • Systemic treatment with retinoids : isotretinoin (Acnetrait®, Procuta®, Curacné®, Contracné®, …).
Show all 22Show fewer
  • Treatment with enzyme-inducing anticonvulsants (carbamazepine, phenobarbital, phenytoin, ….).
  • Participant who has received immunoglobulins, a transfusion of blood or blood derivatives in the last 3 months.
  • Known or suspected congenital or acquired immunodeficiency; immunosuppressive treatment in the last 6 months, such as cancer chemotherapy or radiotherapy; long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks in the last 3 months)
  • Known allergy to antibiotics of the tetracycline family.
  • Known allergy to any component of the Bexsero® vaccine.
  • Known allergy to any component of the doxycycline pill.
  • Known allergy to latex (contained in the vaccine cap).
  • Thrombocytopenia or any other known coagulation disorder, which would be a contraindication to an intramuscular injection of Bexsero® vaccine.
  • Documented oesophageal lesion
  • Acute respiratory infection or severe acute febrile illness or systemic reaction that may present a significant risk if vaccinated in the month prior to inclusion.
  • Any condition (clinical) that, in the investigator's opinion, would contraindicate intramuscular vaccination and blood sampling.
  • Oral Anticoagulant treatment.
  • Continuous treatment with doxycycline at inclusion.
  • Vitamin A treatment in case of intake of 10 000 international unit or more.
  • Participation in another research including an exclusion period still in progress at the time of inclusion.
  • Under guardianship or curator, or deprived of liberty by a judicial or administrative decision.

Trial locations and contacts

9 sites in 1 country.

9 sites in 1 country

France9 sites

  • Hôpital Bichat

    Paris, 75000

  • Hôpital Hôtel Dieu

    Paris, 75181

  • Hôpital Saint-Louis

    Paris, 75475

  • Hôpital Saint-Antoine

    Paris, 75571

  • Hôpital pitié Salpetrière

    Paris, 75651

  • Hôpital Pitié-Salpétrière

    Paris, 75651

  • Hôpital Necker-Enfants Malades

    Paris, 75743

  • Hôpital Européen Georges Pompidou

    Paris, 75908

  • Hôpital Tenon

    Paris, 75970

Other trials in France

About this study

The study ANRS 174 Doxyvac is a clinical trial that will use Combined Prevention of Sexually Transmitted Infections (STIs) in Men Who Have Sex with Men and using oral TDF/FTC for HIV Pre-Exposure Prophylaxis (PrEP) and vaccination with Bexsero.

Read the detailed description

This is a randomized study with a factorial design for the 2 biomedical interventions (interventions 1 and 2).

Subjects will be randomized and assigned to two different interventions:

  • Intervention 1: PEP with doxycycline or no PEP. Subjects will be randomized 2/1 to receive doxycycline PEP or no PEP
  • Intervention 2: Meningococcal B vaccine (Bexsero®) or no vaccine Subjects will be randomized 1/1 to received 2 doses of Bexsero® vaccine (at the first visit and two months later) or no vaccine

Participants will be randomized in one of the following arms:

  • Arm 1: doxycycline and Bexsero® vaccine (240 participants)
  • Arm 2: doxycycline and no Bexsero® vaccine (240 participants)
  • Arm 3: no doxycycline and Bexsero® vaccine (120 participants)
  • Arm 4: no doxycycline and no Bexsero® vaccine (120 participants)

Randomization will be stratified by whether or not the participant enters in the ancillary study "intestinal microbiota".

Being tested
Experimental: doxycycline, Bexsero® vaccine
Keywords
STI infection, PREVENTION
Medical subject headings
Unsafe Sex, Risk-Taking

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Experimental: doxycyclineDrug

    2 tablets of doxycycline 100 mg (monohydrate form) will be taken orally after each risk sexual intercourse, ideally within 24 hours after sex and no more than 72 hours. PEP should not be taken more than 3 times over a 7 days' period.

    If a participant has risk sexual intercourse for several consecutive days, PEP should be taken at least 48 hours apart and no more than 3 times 2 tablets over 7 days. A maximum of 3 intakes of 2 tablets will be allowed over a period of 7 days.

  • Bexsero® vaccineBiological

    1st injection of Bexsero® vaccine at inclusion visit, 2nd injection at week 8.

Study groups in NCT04597424
Study groupRoleWhat they receive
doxycycline and Bexsero® vaccineExperimental-doxycycline will be taken by participants as PEP (prophylaxy post exposition) and participants will received Meningococcal B vaccine (Bexsero®) at D0 and M2
Receives: Drug: Experimental: doxycycline; Biological: Bexsero® vaccine
doxycyclineExperimental-doxycycline will be taken by participants as PEP (prophylaxy post exposition)
Receives: Drug: Experimental: doxycycline
Bexsero® vaccineExperimental-Meningococcal B vaccine (Bexsero®) at D0 and M2
Receives: Biological: Bexsero® vaccine
No treatmentNo intervention-no doxycycline and no Bexsero® vaccine

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. For intervention 1 (with or without doxycycline PEP) : 1st occurence of chlamydia or syphilis after the enrolment visit (Day 0)

    Intervention 1 (with or without doxycycline PEP) is the first episode of chlamydia or syphilis after the enrolment visit (Day 0) (chlamydia and syphilis diagnosed at the enrolment visit will not be included in the primary endpoint).

    Chlamydia détection will be performed by polymerase chain reaction.Syphilis détection will be performed by antigen.

    Measured: Month 24

  2. For intervention 2 with or without Bexsero® vaccine : 1st occurence of gonorrhea reported one month after the second vaccine injection

    Intervention 2 (with or without Bexsero® vaccine) is the first episode of gonorrhea reported one month after the second vaccine injection, so starting at the month 3 visit (gonorrhea episodes diagnosed at the enrolment visit and before the month 3 visit will not be included in the primary endpoint).

    In these analyses, subject follow-up will be right-censored at the time of the first STI.

    Gonorrhea détection will be performed by polymerase chain reaction.

    Measured: Month 24

Secondary outcomes (15)

  1. - Occurrence of a first episode of each of the bacterial STIs as well as cumulative incidence of each bacterial STIs

    • Occurrence of a first episode of each of the bacterial STIs as well as cumulative incidence of each bacterial STIs (syphilis, chlamydia; gonorrhoea and Mycoplasma genitalium) during the trial. In that case, the entire follow-up will be considered.

    Chlamydia détection will be performed by polymerase chain reaction. Syphilis détection will be performed by antigen.

    Mycoplasma genitalium be performed by polymerase chain reaction. Gonorrhea détection will be performed by polymerase chain reaction.

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  2. - Occurrence of a new episode of anal or urinary gonorrhoea.

    • Occurrence of a new episode of anal or urinary gonorrhoea. Gonorrhea détection will be performed by polymerase chain reaction.

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  3. - Occurrence of a first symptomatic episode of chlamydia infection or gonorrhea

    • Occurrence of a first symptomatic episode of chlamydia infection or gonorrhea at urinary or anal sites.

    Chlamydia détection will be performed by polymerase chain reaction. Gonorrhea détection will be performed by polymerase chain reaction.

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  4. - Proportion of patient with Methicillin-Resistant Staphylococcus Aureus and/or doxycycline resistant Staphylococcus aureus from throat. Fecal carriage of Extended-Spectrum Beta-Lactamase-producing Enterobacteriaceae Composition of intestinal microbiota

    detection from throat swab of carriage of MRSA (methicillin-resistant Staphylococcus aureus) and/or doxycycline resistant Staphylococcus aureus, fecal carriage of ESBL (extended-spectrum beta-lactamase) -producing Enterobacteriaceae, and composition of the intestinal microbiota), all détected by polymerase chain reaction assay

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  5. - Incidence of clinical and biological adverse events

    Proportion of patients experiencing a clinical or biological adverse events (ANRS scale)

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  6. - Proportion of patients taking doxycycline

    Adherence will be evaluated by doxycycline pills taken by patients

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  7. - Concentration of doxycycline in hair

    Adherence will be evaluated by détection of doxycyclin in hair

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  8. - Proportion of patients with Antibiotic susceptibilities of all strains of NG (Neisseria gonorrhoeae), CT (chlamydiae trachomatis), MG (mycoplasma genitalium)

    identification of Antibiotic susceptibilities of all strains of NG (Neisseria gonorrhoeae), CT (chlamydiae trachomatis), MG (mycoplasma genitalium) to doxycycline, macrolides, fluoroquinolones and third generation cephalosporin will be performed by PCR (polymerase chain reaction assay)

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  9. - Rate of cured STIs after treatment with or without PEP.

    declaration of illnesses from infection to healing

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  10. - Incidence of resistance to antibiotics of Neisseria gonorrhoeae with or without doxycycline.

    Proportion of participants with resistance to antibiotics of Neisseria gonorrhoeae will be evaluated by polymerase chain reaction to detect mutations

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  11. - Incidence of Serum bactericidal activity against meningococcal and gonococcal antigens over time in participants of Bexsero®'s arm.

    Proportion of participants with Serum bactericidal activity against meningococcal and gonococcal antigens

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  12. - Incidence of clinical and biological adverse events following Bexsero® vaccine.

    Proportion of participants experiencing a clinical and biological adverse events following Bexsero® vaccine (ANRS scale)

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  13. - Prevalence and incidence of meningococcal carriage in pharyngeal, anal and urine swabs.

    detection of meningococcal carriage in pharyngeal, anal and urine swabs will be performed

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  14. - Impact of PEP or Bexsero® vaccine on sexual behaviour

    rates of condom use for receptive anal intercourse, number of sexual partners and number of sex acts over time

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

  15. - Incidence of HIV infection with both prophylaxis strategies.

    HIV infection will be tested by serology and western blot assay

    Measured: Month 2, Month 3, Month 6, Month 12, Month 18, Month 21, Month 24

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted22 Oct 2020
  2. Study start19 Jan 2021
  3. Primary completion19 Feb 2023
  4. Study completion19 Apr 2024

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Model description
Arm 1 : doxycycline and Bexsero vaccine Arm 2 : doxycycline and no vaccine Arm 3 : No doxycycline and Bexsero vaccine Arm 3 : No doxycycline and No Bexsero vaccine
Masking
None (open label)
Enrolment
556 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04597424
Sponsor's protocol ID
ANRS 174 DOXYVAC
Other IDs
2019-002829-29, 2019
Acronym
DOXYVAC
Status last verified
Apr 2026
First submitted
1 Oct 2020
Last updated
6 Apr 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No

Publications

  • Molina JM, Bercot B, Assoumou L, Rubenstein E, Algarte-Genin M, Pialoux G, Katlama C, Surgers L, Bebear C, Dupin N, Ouattara M, Slama L, Pavie J, Duvivier C, Loze B, Goldwirt L, Gibowski S, Ollivier M, Ghosn J, Costagliola D; ANRS 174 DOXYVAC Study Group. Doxycycline prophylaxis and meningococcal group B vaccine to prevent bacterial sexually transmitted infections in France (ANRS 174 DOXYVAC): a multicentre, open-label, randomised trial with a 2 x 2 factorial design. Lancet Infect Dis. 2024 Oct;24(10):1093-1104. doi: 10.1016/S1473-3099(24)00236-6. Epub 2024 May 23.

    PubMed 38797183

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Experimental: doxycycline and Bexsero® vaccine in people with Unsafe Sex and Risk-Taking, run by ANRS, Emerging Infectious Diseases at 9 sites in France.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 22 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 6 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 9 sites in France. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

For intervention 1 (with or without doxycycline PEP) : 1st occurence of chlamydia or syphilis after the enrolment visit (Day 0) (time frame: Month 24). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04597424, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Apr 2026.

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