The meningococcal B vaccine is ineffective in gonorrhoea prevention amongst men who have sex with men (MSM) at high risk of infection, according to findings from the world’s largest randomised control trial (RCT) into possible efficacy published in the New England Journal of Medicine (NEJM).

The double-blind, randomised, placebo-controlled trial called ‘GoGoVax’ published today in the NEJM was led by Professor Kate Seib from the Institute for Biomedicine and Glycomics at Griffith University and  Professor Andrew Grulich from the Kirby Institute at UNSW Sydney. The trial involved 587 gay and bisexual men at high risk of gonorrhoea infection who received either the meningococcal vaccine or a saline placebo.

Contrary to evidence in observational studies that led to vaccination programmes abroad, GoGoVax found that 4CMenB (meningococcal B vaccine) had no effect on incidence of gonorrhoea.

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

These findings come after the UK Government began offering the meningococcal B vaccine to gay and bisexual men at high risk of gonorrhoea in August 2025, while the Galician (Spain) government implemented a meningococcal B vaccination programme for adults at high risk of gonorrhoea in June 2025. The programmes follow several observational studies suggesting the vaccine could reduce gonorrhoea risk.

“Gonorrhoea 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 gonorrhoea, 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-setting aimed at preventing STIs,” said Prof Seib.

“The results of our research, while incredibly disappointing, provide clear and compelling evidence that the 4CMenB vaccine is not effective for preventing gonorrhoea 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 UK and Galicia towards the crucial task of reducing the incidence of gonorrhoea, where they have responded to evidence in observational studies. Unfortunately, GoGoVax’s and other RCT findings do not support the implementation of meningococcal B vaccinations for gonorrhoea prevention for men who have sex with men and suggest those jurisdictions may need to reconsider their current programmes,” said Prof 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 gonorrhoea 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 gonorrhoea infection, such as condoms and regular testing which they can access via sexual health clinics and community-based testing services,” said Prof Seib.

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

GoGoVax was conducted amongst gay and bisexual men who had a recent history of gonorrhoea or syphilis, and these groups were chosen as they were more likely to acquire gonorrhoea over the course of the study. It is possible that the high rates of gonorrhoea history among the GoGoVax study population make 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 gonorrhoea infection, with results expected within a year.

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

Contrast of RCT and observational studies findings

The data coming out of observational studies pointing towards cross protection offered by 4CMenB was seen as biologically plausible due to 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, randomisation removes all possible confounding factors.

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

“GoGoVax’s data demonstrate that good-quality randomisation was achieved, and people randomised 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 Prof 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 gonorrhoea in the community,” said Prof Seib.