Efficacy of a Meningococcal B Vaccine and a Preventive Antibiotic in Reducing the Risk of Sexually Transmitted Infections

Vaccination © Adobe Stock

The ANRS DOXYVAC trial, conducted by a research team from the Paris public hospitals group (AP-HP), Université Paris Cité, Inserm and Sorbonne Université in collaboration with AIDES and Coalition PLUS, demonstrates the efficacy of both a meningococcal B vaccine in reducing the risk of gonorrhea infection and the use of doxycycline as preventive intervention for sexually transmitted infections when taken within 72h after sexual intercourse. In the wake of these results and taking into account the recommendations of the data and safety monitoring board, the scientific leaders and sponsor have decided to discontinue the trial and recommend the provision of both interventions to all its participants. This study is sponsored and funded by ANRS | Emerging Infectious Diseases in partnership with Roche[1].

According to World Health Organization (WHO) estimates, over 374 million people each year are diagnosed with a sexually transmitted infection (STI), which includes bacterial infections such as syphilis, chlamydia and gonorrhea. These bacterial infections particularly affect young people, men who have sex with men (MSM), and ethnic minorities. They are responsible for impaired quality of life and can cause serious side effects during pregnancy with congenital syphilis, risks of infertility in women and globally increase the risk of HIV infection.

In recent years, an increase in these STIs has been observed in France, particularly among MSM, making them a major public health problem for which new means of prevention must be developed.

Over the past few years, several research teams worldwide have been studying the efficacy of antibiotics used as prophylaxis in reducing the risk of STIs. This concept of post-exposure prophylaxis was first evaluated in the ANRS IPERGAY trial, which demonstrated that doxycycline, when used within 72h after sexual intercourse, led to an approximately 70% reduction in the risk of infection with chlamydia and syphilis.

In parallel, a certain number of epidemiological studies have reported in recent years that people receiving the Bexsero® meningococcal B[2] vaccine may have a reduced risk of gonorrhea infection by around 30%[3].

ANRS DOXYVAC differs from the other trials by the evaluation in a prospective, randomized trial of the combination of post-exposure prophylaxis with doxycycline and vaccination with Bexsero®. This study has been conducted since January 2021 in MSM, highly exposed to the risk of STIs and having presented at least one STI in the year prior to their participation in it. These men also participate in the ANRS PREVENIR cohort for the prevention of HIV infection whose results have recently been reported in The Lancet HIV and which showed that taking PrEP on demand was as effective and safe as its daily administration in preventing HIV infection.

ANRS DOXYVAC therefore forms part of a global, combined prevention framework in association with other risk reduction measures (repeated HIV and STI screening, hepatitis A and B vaccinations, distribution of condoms and gel) and with the possibility of community support or therapeutic education. Over 500 volunteers living in the Paris region[4] were randomly assigned to four groups: one receiving post-exposure prophylaxis with doxycycline, the other vaccination with Bexsero®, the third a combination of the two interventions, and the fourth neither of the two interventions.

Following the results of the US DOXYPEP study – presented at the International AIDS Conference in July 2022 in Montreal – and following an analysis of the data on the incidence of STIs among the ANRS DOXYVAC study participants, conducted at the request of the data and safety monitoring board, it was found that:

  • The doxycycline group presented a significant reduction in the risk of syphilis and chlamydia infections. The incidence of gonorrhea infections was also significantly reduced.
  • The meningococcal B vaccine group presented a significant reduction in the risk of gonorrhea infection.

According to the recommendations of the data and safety monitoring board, the scientific leaders and ANRS | Emerging Infectious Diseases, as sponsor, have therefore decided to stop the study in its current form in order to make doxycycline and the meningococcal B vaccine available to all ANRS DOXYVAC participants, following validation by the regulatory and ethical authorities. The follow-up of the participants will continue until the end of 2023 to ensure that these prevention strategies are effective in the medium term.

The results of the study have been submitted for presentation at an international congress in early 2023.

According to the study’s coordinating investigator, Prof. Jean-Michel Molina (Department of Infectious Diseases at Saint-Louis and Lariboisière Hospitals AP-HP, and Université Paris Cité) :

the concept of biomedical prophylaxis at the time of exposure to the risk of sexually transmitted infections as part of an expanded prevention offering is therefore validated. We owe this to all the study volunteers without whom it would not have been possible to demonstrate this efficacy.” He adds: “however, the efficacy observed must not overshadow the fact that condoms remain the cornerstone of STI prevention in general. It is by adding together all the prevention tools that have proved themselves that we will be able to effectively control STIs and achieve the WHO and UNAIDS objective for 2030, which is to reduce their incidence by 90%.

It is a major step forward in the fight against STIs. The results of ANRS DOXYVAC should bring about changes to the national and international recommendations for the prevention of these diseases. This research project in its collaborative form with the associations AIDES and Coalition PLUS is showing particular promise when it comes to the future implementation of the recommendations.” affirms Prof. Yazdan Yazdanpanah, Director of ANRS | Emerging Infectious Diseases.


[1] Roche Molecular System and Roche Diagnostics France provided – free of charge – the kits, consumables and reagents needed to detect chlamydia, neisseria and mycoplasma.

[2] Meningococcus B (Neisseria meningitidis) is a bacterium that can cause meningitis. It is close to gonococcus (Neisseria gonorrhoeae).

[3] Observational studies conducted in New Zealand, USA, Australia and Canada.

[4] The participants were enrolled at the following hospitals of the Paris public hospitals group (AP-HP): Saint-Louis, Tenon, Pitié-Salpêtrière, Bichat Claude-Bernard, Saint-Antoine, Hôtel-Dieu, Necker, Garches, and Lariboisière.

Preventing dementia in seniors: meditation still under investigation


Meditation as a tool to prevent dementia and improve the mental health and well-being of elderly people is one of the avenues explored by the European Medit-Ageing research program, coordinated by Inserm. As part of this program, researchers from Inserm and Université de Caen Normandie, in collaboration with French and European teams, observed the impact of 18 months of meditation training on certain brain structures involved in regulating attention and emotions in healthy people over 65. While their findings, to be published in JAMA Neurology, show a positive impact on attentional and socio-emotional regulation capacities, they do not show any significant benefits of meditation on the volume and functioning of the brain structures studied, in comparison to control groups. However, they do call for further research to study the brain as a whole, over longer time periods, and with more participants.

In order to prevent the onset of dementia in elderly people, recent intervention strategies have been multidisciplinary and focused on lifestyle improvements. These include cognitive stimulation, physical activity, a healthy diet, and cardiovascular recommendations. However, there are no dedicated preventive interventions for psycho-affective factors such as depression, stress, and anxiety.

Mental training aimed at regulating stress and attention, such as mindful meditation, has proven to be beneficial in managing the cognitive and emotional aspects of aging, particularly to reduce stress, anxiety, and depression.

Recent research has reported that the insula and anterior cingulate cortex are brain regions particularly sensitive to meditation training. These interconnected regions are involved in self-awareness and in the processing and regulation of attention, emotions, and empathy. In young adults, meditation has already shown its capacity to structurally (e.g. in terms of volume) and functionally modify these structures, particularly in the brain of meditation experts with several thousand hours of practice under their belts.

The insula and anterior cingulate cortex are particularly sensitive to aging. It has been shown that in elderly people who are experts in meditation, gray matter volume and glucose metabolism (a physiological process essential for good brain function) were higher than in people who do not meditate.

Meditation could therefore be an interesting approach to preserve brain structures, functions, and cognitive capacities, and by extension, prevent dementia.

A team of researchers from the European Medit-Ageing research group, led by Inserm Research Director Gaël Chételat from the Physiopathology and Imaging of Neurological Disorders laboratory (Inserm/Université de Caen Normandy), in collaboration with teams from Lyon Neuroscience Research Center (Inserm/CNRS/Université Claude Bernard Lyon 1/Université Jean-Monnet-Saint-Etienne), University College London, University of Liège and University of Geneva, looked at the potential physiological, cognitive, and emotional benefit of meditation in elderly individuals.

In the Age-Well clinical trial involving 136 participants aged 65 or older with no known diseases, the researchers measured the impact of an 18-month meditation intervention on tissue volume and perfusion (physiological process of supplying an organ with nutrients and oxygen necessary for its metabolism) of the insula and anterior cingulate cortex. They also looked at specific cognitive and socio-affective parameters.

The participants were assigned to three groups in order to compare the potential benefit of meditation with different types of interventions. The first group followed the meditation intervention protocol (mindfulness meditation and loving kindness and compassion meditation), the second group (the “active control” group) followed a period of English-language training, and the third group (the “passive control” group) did not follow any intervention.

After 18 months of intervention, the researchers saw no significant changes in volume or perfusion of the cingulate cortex or insula in the meditation group compared to the control groups.

The fact that no anatomical differences were observed between these two groups could indicate that while meditation can modify the volume of younger and more plastic brains, 18 months of meditation training are not enough to modify the effects of aging,” analyzes Chételat. “In addition, while the results of the volume measurement are strictly negative, those of the perfusion show a trend in favor of meditation that could be interesting to explore over a longer intervention time and/or with a larger population sample,” specifies the researcher.

The research team will therefore conduct a 4-year follow-up of the participants, to investigate potential long-term effects.

In contrast, significant differences were observed in behavioral measures between the meditation group and the English-learning group, with improved regulation of attention and socio-emotional capacities in the meditation group participants. “Here the practice of meditation is showing its real benefit on the mental health of elderly people, with a significant improvement in parameters specific to well-being and fulfilment, but also to the maintenance of attentional and socio-emotional capacities, as reported by participants,” adds Antoine Lutz, responsible for the study’s meditation component.

More specific measurements and analyses will be conducted within the Age-Well trial to improve the understanding of these mechanisms. These analyses could be used to identify the measures which are most sensitive to meditation and to study the mechanisms behind its effects.



To find out more about the latest medical research on consciousness, read the special feature “Consciousness: modulating it to improve treatment” in issue 54 of Inserm, le magazine 

New Avenues to Reduce Long-Term Complications in Preterm Infants

Some GnRH neurons (green) express NOS1 (red) during their migration from the nose to the brain during fetal life. The GnRH + NOS1 double-labeled cells appear in yellow. © Vincent Prévot/Inserm

Children born prematurely have a higher risk of not just cognitive and sensory disorders, but also infertility in adulthood. In a new study, a team of researchers from Inserm, University Hospital Lille and Université de Lille at the Lille Neuroscience and Cognition laboratory has opened up interesting avenues for improving their prognosis. By conducting research into a rare disease known as congenital hypogonadotropic hypogonadism, the scientists have discovered the key role of an enzyme and the therapeutic potential of the neurotransmitter that it synthesizes – nitric oxide – in reducing the risk of long-term complications in the event of prematurity. Their findings are described in Science Translational Medicine.

Congenital hypogonadotropic hypogonadism is a rare disease characterized by delayed puberty or the complete absence of puberty in adolescence, leading to infertility. Some forms of the disease are caused by a lack of production of GnRH, a hormone produced in the brain that remotely controls the development and functioning of male and female gonads through various intermediaries.

The team of Vincent Prévot, Inserm Research Director, specializes in the dialogues between the brain and the rest of the body.

Here the scientists looked at nitric oxide, a neurotransmitter that regulates the activity of GnRH neurons, and more specifically NOS1, the enzyme that synthesizes it.

“Nitric oxide suppresses the electrical activity of the GnRH neurons and modulates the release of this hormone, so NOS1 dysfunction was not ruled out as being the cause of congenital hypogonadotropic hypogonadism,” explains Prévot, the principal coordinator of the study.

To go further, his team collaborated with a laboratory in Lausanne (Switzerland) which has a cohort of 341 patients with this disease. Using DNA samples, they looked for the presence of rare mutations on the gene encoding the NOS1 enzyme and found five different mutations that could explain the disease. Some of the individuals concerned had, in addition to fertility problems, sensory and cognitive disorders (intellectual disability or loss of hearing or smell).

An application in the context of preterm birth?

The next stage of the study consisted of developing a NOS1-deficient mouse model[1] in order to better understand the role of this enzyme. The researchers encountered puberty problems, as well as sensory and neurological alterations, as observed in humans with congenital hypogonadotropic hypogonadism. They also saw an exacerbation of minipuberty in these animals. Minipuberty occurs in all mammals just after birth (between one and three months of age in humans) and triggers an initial brain activation of the axis controlling reproduction prior to the “real” puberty in adolescence.

Here the researchers observed that the peak of the sex hormone associated with this minipuberty was twice as high in NOS1-deficient mice.

“This caught our attention because premature infants also tend to present a more intense minipuberty than usual. And the greater the prematurity, the greater the risk of neurosensory and mental complications in adulthood,” reiterates Konstantina Chachlaki, Inserm researcher and first author of the study.

Based on these observations, the researchers tested the administration of nitric oxide in NOS1-deficient mice just after their birth, during the minipuberty period. What they saw was the reversal of all the symptoms they had developed: the puberty problems and sensory and neurological disorders disappeared, and this was over the long term, for the remainder of their lives.

An ongoing clinical trial

These promising findings could help to improve the care of preterm infants. Nitric oxide is also given to some children born prematurely, to facilitate the opening of the bronchi in the event of breathing difficulties.

“In light of this consistency of observations and practices, we decided to set up a clinical trial to test the effect of nitric oxide in preterm infants by studying reproductive and neurosensory parameters,” explain Prévot and Chachlaki, who are coordinating a European project dedicated to…“Administering nitric oxide at birth could reduce the risk of reproductive, sensory and intellectual complications in children born prematurely. This is what we are going to try to verify in the wake of these astonishing discoveries in mice,” they continue.

The miniNO trial was launched at University Hospital Lille in partnership with a hospital in Athens (Greece). The objective is to verify whether children receiving this treatment go on to experience normal minipuberty and puberty, and whether they develop fewer sensory and neurological complications compared to premature infants who were not administered nitric oxide at birth.


[1] In which the gene encoding the NOS1 enzyme was disactivated.