(DENVER, Wednesday 25 February 2026) In a significant revelation that challenges previous research, the meningococcal B vaccine (4CMenB) has been found ineffective in preventing gonorrhoea, according to the world’s largest randomised control trial (RCT) on the subject. Conducted by Griffith University’s Institute for Biomedicine and Glycomics and the Kirby Institute at UNSW Sydney, the findings were unveiled at the Conference on Retroviruses and Opportunistic Infections in Denver, Colorado.
Gonorrhoea continues to pose a substantial public health challenge, particularly due to the emergence of antibiotic-resistant strains. The study specifically targeted gay and bisexual men, who are at a higher risk of contracting the infection. The trial, which was double-blind, randomised, and placebo-controlled, included 587 participants who received either the meningococcal vaccine or a saline placebo.
“Across both arms, the gonorrhoea incidence was virtually the same – at around 48 per cent per year, indicating very clearly that the vaccine had no effect on preventing gonorrhoea,” said Professor Kate Seib from Griffith University, who led the trial.
Study Results and Implications
The study’s results align with the earlier DOXYVAC open-label trial, which also found no significant impact of the 4CMenB vaccine on gonorrhoea prevention. Together, these studies provide compelling evidence against the vaccine’s efficacy in this context, particularly among gay and bisexual men at high risk.
Professor Andrew Grulich from the Kirby Institute, a co-lead on the study, expressed disappointment at the findings, noting the potential transformative impact an effective gonorrhoea vaccine could have had on public health strategies.
“An effective vaccine to reduce gonorrhoea would transform our approach to prevention, so it is incredibly disappointing that our research has proven that 4CMenB is not effective in gonorrhoea prevention in gay and bisexual men,” Grulich stated.
Alternative Prevention Strategies
Despite the setback, the meningococcal B vaccine remains a safe and effective measure against meningococcal disease, approved in Australia since 2013. However, those who have received the vaccine in hopes of gonorrhoea prevention are advised to explore other preventive measures, such as condom use and regular testing.
Professor Grulich emphasized the importance of sexual health clinics and community-based testing services as critical components of gonorrhoea prevention strategies.
Understanding the Study Population
The trial focused on gay and bisexual men with a recent history of gonorrhoea or syphilis, selected due to their higher likelihood of contracting gonorrhoea during the study. The high prevalence of gonorrhoea history in this group may have influenced the vaccine’s apparent ineffectiveness.
Brent Mackie, Director of Policy, Strategy and Research at ACON, highlighted the importance of such research in providing clarity and refining STI prevention approaches.
“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,” Mackie said.
Discrepancies with Observational Studies
The RCT, named ‘GoGoVax,’ was initiated following observational studies suggesting a link between the meningococcal B vaccine and reduced gonorrhoea incidence. These studies, however, can be influenced by confounding factors, which the RCT aimed to eliminate through rigorous randomisation.
“Some case-control studies have compared the meningococcal B vaccination history of people who have gonorrhoea to the vaccination history of people who have chlamydia. In these studies, people who acquired gonorrhoea had lower 4CMenB vaccination rates than expected, suggesting that the vaccine may have prevented gonorrhoea. However, other confounding factors might explain the differences in vaccine history between the other two groups,” explained Prof Grulich.
RCTs are regarded as the gold standard in medical research due to their ability to minimise confounding factors and establish cause-and-effect relationships.
“In GoGoVax, our data demonstrate that good-quality randomisation was achieved, and people randomised to receive vaccine or placebo had balanced levels of confounding factors,” Prof Grulich noted.
Despite the disappointing outcome, the study underscores the importance of continued research and collaboration with at-risk communities to explore alternative prevention methods for gonorrhoea.
