PARIS – All the way back in 1907, The Lancet published an article on a gonorrhea vaccine trial. Today, after continuous research throughout the intervening 110-plus years, scientists may finally have achieved success. Sébastien Fouéré, MD, discussed the details at a press conference that focused on the highlights of the Dermatology Days of Paris conference. Dr. Fouéré is the head of the genital dermatology and sexually transmitted infections unit at Saint-Louis Hospital, Paris.
Twin bacteria
Although the gonorrhea vaccine has long been the subject of research, Dr. Fouéré views 2017 as a turning point. This was when the results of a study led by Helen Petousis-Harris, PhD, were published.
“She tried to formalize the not completely indisputable results published by Cuba, where it seemed there were fewer gonococci in individuals vaccinated against meningococcal group B,” he noted.
Dr. Petousis-Harris, an immunologist, conducted a retrospective case-control study involving 11 clinics in New Zealand. The participants were aged 15-30 years, were eligible to receive the meningococcal B vaccine, and had been diagnosed with gonorrhea, chlamydia, or both. The researchers found that receiving the meningococcal B vaccine in childhood provides around 30% protection against Neisseria gonorrhoeae infections.
“It’s not perhaps a coincidence that a meningococcal B vaccine would be protective against gonorrhea,” Dr. Fouéré pointed out. He considers this protection logical, even expected, insofar as “meningococcus and gonococcus are almost twins.” There is 90% and 100% homology between membrane proteins of the two bacteria.
Vaccine is effective
Two retrospective case-control studies confirm that the vaccine is protective. One of the studies, carried out by an Australian team, found that the effectiveness was 32%, quite close to that reported by Petousis-Harris. In the other study, a U.S. team brought to light a dose-response relationship. while a complete vaccination series (two MenB-4C doses) was 40% effective.
Prospective studies are in progress, which will provide a higher level of evidence. The ANRS DOXYVAC trial has been underway since January 2021. The participants are men who have sex with men, who are highly exposed to the risk of sexually transmitted infections, and who presented with at least one STI in the year before their participation in the study. “The study is being conducted by Jean-Michel Molina of Saint-Louis Hospital. What they’re trying to do is protect our cohort of pre-exposure prophylaxis patients with meningococcal vaccine,” explained Dr. Fouéré.
Initial findings demonstrated the efficacy of a meningococcal B vaccine in reducing the risk of gonorrhea and the efficacy of doxycycline as preventive intervention for STIs when taken within 72 hours after sexual intercourse. In light of these results, a decision was made at the end of October to discontinue the trial and to recommend providing both interventions to all ANRS DOXYVAC participants. The follow-up of the participants will continue until the end of 2023. The results that led to stopping the study in its current form will be presented in early 2023.
This article was translated from the Medscape French edition. A version of this article appeared on Medscape.com.