CROI 2023: Reporting from Margarita Breakfast Club Session 2

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Moving Forward: Upcoming Strategies on STI Prevention



Dr. Jean-Michel Molina, University of Paris Cité

Jonathan Ayala, NMAC, CROI Community Educator Scholar


Jim Pickett, AVAC

Tuesday 21 February 2023


In the second of the three MBC sessions we heard from Dr Jean-Michel Molina, University of Paris Cité, on the hot topic of doxycycline as post-exposure prophylaxis for bacterial STIs, mainly gonorrhoea, chlamydia and syphilis. Studies converge on the efficient and persistent concentration of doxy in mucous membranes, particularly the rectal mucosa, which is why doxycycline has proven its efficacy in men who have sex with men (MSM).


The ANRS 174 DoxyVAC Study presented by Dr Jean-Michel Molina is an open-label, randomised trial that started in 2021 and combined doxycycline (associated with a reduction of chlamydia and syphilis in MSM) and a 4CMenB vaccine (against type B meningococcal disease, also associated with reduction of gonorrhoea). The study was conducted in MSM who were already on a PrEP regimen for a minimum of 6 months and who have had at least one episode of STI in the year preceding the study. The trial involved 502 participants from the Ile-de-France region, who were divided into two active arms compared to two control groups using a 2×2 factorial randomized design:


  • A group receiving post-exposure prophylaxis (PEP) with doxycycline (200mg, within 24-72 hours post sex) vs. a control arm,
  • A group receiving 4CMenB vaccination (2 injections) vs. a control arm.


The results on chlamydia and syphilis were particularly good, which showed a reduction in incidence of up to 80%, but also on gonorrhoea with a reduction of 55%. Following these results and the effectiveness of both interventions, the Data and Safety Monitoring Board (DSMB) decided to stop the recruitment of new participants in September 2022 and made Doxy-PEP and the 4CMenB vaccine available to all participants in the trial, if they wished. The follow-up visits of participants will continue until the end of 2023 to ensure the medium-term effectiveness of these prevention strategies.


In addition, more studies are in the pipeline: two efficacy studies of 4CMenB to prevent gonorrhoea (one in Australia with gay, bisexual men and another MSM on PrEP or living with HIV, one in the US and Thailand with cisgender men and women).


Dr Molina concluded highlighting that Doxy-PEP is well-tolerated and has high rates of self-reported adherence, that data have shown significant reductions of STIs among MSM and that 4CMenB vaccine reduced gonorrhoea incidence among MSM on PrEP. As always, there is no silver bullet but an approach based on combination prevention is still key.


From a community perspective, Jonathan Ayala, NMAC & CROI Community Educator Scholar, makes some considerations on how to move forward with strategies on STI prevention. Doxy-PEP is indeed a useful tool for people to maintain their physical and sexual health, reduce the frequency of STIs and it is effective for both people living with and not living with HIV. However, it is important to make clear that this is post-exposure prophylaxis, but different from HIV PEP and different from, but complementary with, PrEP. Information on this prevention tool needs to be accessible and clear and providers would need to be trained on how to appropriately offer this new tool to those who might be interested. Further evidence on antibiotic resistance must also be explored, before the tool is implemented. Additionally, messaging needs to be clear and upfront that cisgender women have once again been left out of this tool and that it is still important to include the needs of cis (and particularly black) women in STI R&D.


It remains therefore crucial to work on how the message is framed and move from a disease-focused approach to a sex-positive framework that is built on pleasure, desire and tools that help us all to have the sex life we want to have.



Click here to watch the recording of the session!



NEXT MBC, Session #3:


Join us for our next Margarita Breakfast Club session on Wednesday 22 February at 7:00 PST / 16:00 CET to discuss how to fill in the missing perspectives on Women and Children HIV Research.


Register here: 


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