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)

Conditions: Unsafe Sex; Risk-Taking

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.

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".

Eligibility criteria:
inclusion criteria: * 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). exclusion criteria: * 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®, ...). * 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.

Keywords: sti infection prevention