Meningococcal B vaccine ineffective in gonorrhea prevention for men who have sex with men

The meningococcal B vaccine is ineffective in gonorrhea prevention among men who have sex with men (MSM) at high risk of infection, according to findings from the world’s largest randomized controlled trial (RCT) into possible efficacy published in the New England Journal of Medicine. Contrary to evidence in observational studies that led to vaccination programs abroad, GoGoVax found that 4CMenB (meningococcal B vaccine) had no effect on the incidence of gonorrhea.

The results support the findings of two other RCTs, DOXYVAC and MenGO, reporting no protective effect of 4CMenB against gonorrhea in MSM at high risk of infection.

These findings come after the U.K. government began offering the meningococcal B vaccine to gay and bisexual men at high risk of gonorrhea in August 2025, while the Galician government in Spain implemented a meningococcal B vaccination program for adults at high risk of gonorrhea in June 2025. The programs follow several observational studies suggesting the vaccine could reduce gonorrhea risk.

“Gonorrhea is a major global sexually transmitted infection that poses an evolving threat to public health, particularly as increasing antimicrobial resistance continues to narrow treatment and control strategies,” said Professor Kate Seib from Griffith University, who led the trial.

“Previous observational studies offered some hope we were closer to identifying a much-needed vaccine for gonorrhea, but unfortunately our research suggests otherwise. Despite this result, research like this provides important clarity to individuals looking out for their sexual health and informs public health policy aimed at preventing STIs,” said Seib.

“The results of our research, while incredibly disappointing, provide clear and compelling evidence that the 4CMenB vaccine is not effective for preventing gonorrhea in men who have sex with men,” said Professor Andrew Grulich from the Kirby Institute, who was also a lead on the study.

“It’s important we acknowledge the efforts in the U.K. and Galicia toward the crucial task of reducing the incidence of gonorrhea, where they have responded to evidence in observational studies. Unfortunately, GoGoVax’s findings and those of other RCTs do not support the implementation of meningococcal B vaccinations for gonorrhea prevention for men who have sex with men and suggest those jurisdictions may need to reconsider their current programs,” said Grulich.

The meningococcal B vaccine was approved for use in Australia in 2013 and is a safe and effective vaccine for preventing meningococcal disease.

“We must reiterate to participants in the trial and others who have received the 4CMenB vaccine in the hope of gonorrhea prevention that while the vaccine cannot provide that, it is very safe and they will receive protection against meningococcal B. People should continue with other methods for preventing gonorrhea infection, such as condoms and regular testing, which they can access via sexual health clinics and community-based testing services,” said Seib.

Building on this research and our understanding of the vaccine’s efficacy

GoGoVax was conducted among gay and bisexual men who had a recent history of gonorrhea or syphilis, and these groups were chosen because they were more likely to acquire gonorrhea over the course of the study. It is possible that the high rates of gonorrhea history among the GoGoVax study population made them less susceptible to any potential protective effects of vaccination.

Several RCTs are ongoing that will examine vaccine efficacy in different populations, including women and people at lower risk of gonorrhea infection, with results expected within a year.

“While our findings cannot be generalized to other populations, they are important for gay and bisexual men at high risk of gonorrhea. The results from other RCTs looking at different populations, as well as the post-implementation surveillance from vaccination programs in the U.K. and Galicia, will be critical to further understanding the role of 4CMenB in gonorrhea prevention,” said Grulich.

Contrast of RCT and observational studies findings

The data coming out of observational studies pointing toward cross-protection offered by 4CMenB was seen as biologically plausible because of the close genetic relationship between Neisseria meningitidis and Neisseria gonorrhoeae. However, observational studies can be affected by what researchers call confounding factors—whereas RCTs are considered the gold standard in medical research because, if conducted correctly, randomization removes all possible confounding factors.

“Several case-control studies comparing the 4CMenB vaccination history of people who have gonorrhea to that of people who have chlamydia found that people who acquired gonorrhea had lower vaccination rates than expected, suggesting the vaccine may have prevented gonorrhea. However, other confounding factors might explain the differences in vaccine history between the two groups,” said Grulich.

“GoGoVax’s data demonstrate that good-quality randomization was achieved, and people randomized to receive vaccine or placebo had balanced levels of confounding factors. A properly conducted RCT provides the strongest possible evidence of a cause-and-effect relationship,” said Grulich.

“Research like this is vital because it helps give our communities the clarity we need. Findings help us refine our approach in preventing the transmission of STIs. We thank everyone who participated in the study. Your contribution will help strengthen sexual health in our communities,” said Brent Mackie, director of policy, strategy and research at ACON, who was a collaborator on the study.

“We acknowledge the gay and bisexual men for their participation and ongoing resilience. That collaboration is crucial as we continue investigating how to reduce gonorrhea in the community,” said Seib.

Who’s behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021.

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Andrew Zinin

Master’s in physics with research experience. Long-time science news enthusiast. Plays key role in Science X’s editorial success.

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