Efficacy of the meningococcal vaccine against Neisseria gonorrhoeae: a randomised clinical trial (MenGO).

Neisseria gonorrhoeae (NG) causes significant morbidity globally, and no licensed vaccine currently exists. Observational studies suggest the four-component meningococcal B (4CMenB) vaccine may provide cross-protection against NG. We conducted MenGO, an open-label, randomized controlled trial to evaluate the efficacy, safety, and immunogenicity of 4CMenB against NG in gay and bisexual men (GBM). Participants were randomized 1:1 to receive two doses of 4CMenB, or no vaccine, and were followed for 2 years with 3-monthly visits. 4CMenB vaccination did not significantly reduce gonorrhoea incidence (incidence rate ratio 0.78 (95% confidence interval (CI) 0.40-1.51;p = 0.457), and no study-related serious adverse events occurred. The vaccine was immunogenic against NG, with higher serum bactericidal activity (hSBA) median titres at 6 months in vaccinated compared to unvaccinated participants (4 [interquartile range (IQR) 2-8] vs 2 [IQR 2-2];p = 0.0021). However, hSBA titres did not increase in participants with an NG infection at the time of vaccination (2 [IQR 2-2] to 2 [IQR 2-4];p = 0·999), whereas those without NG infection showed an increase from baseline to 6 months (2 [IQR 2-4] to 6 [IQR 2-16];p = 0.0089). This study is limited by its small sample size based on an assumed vaccine efficacy of >67% and was impacted by the COVID-19 pandemic. These findings provide important information for current 4CMenB vaccines programmes and gonorrhoea vaccine development and implementation.