Defining the Efficacy of Meningococcal B Vaccines Against Gonococcal Acquisition: The Current Landscape

Gonorrhoea is a major global sexually transmitted infection, with rising incidence and increasing antimicrobial resistance threatening current control strategies. If untreated, Neisseria gonorrhoeae can lead to severe reproductive health sequelae. Gonorrhoea is also linked to increased HIV acquisition and transmission. There is currently no vaccine licensed to prevent gonorrhoea. However, observational evidence suggests that outer membrane vesicle-based serogroup B meningococcal vaccines, including the four-component meningococcal B (4CMenB) vaccine, confer partial cross-protection against gonorrhoea. We discuss observational studies and randomized controlled trials (RCTs) focused on defining the efficacy of 4CMenB against gonorrhoea.

Observational studies from multiple settings have reported an association between receipt of 4CMenB vaccine and reduced gonorrhoea risk, with a meta-analysis estimating a 38% reduction in risk. Neisseria meningitidis and N. gonorrhoeae are closely related bacteria that share numerous antigens, making cross-protection biologically plausible. Based on observational data, 4CMenB immunization programmes have been implemented in two countries with the aim of preventing gonorrhoea. However, three RCTs have recently shown that 4CMenB is not effective in preventing gonorrhoea in gay, bisexual and other men at high risk of acquisition. Several RCTs are ongoing, looking at efficacy in different populations, including women and people at lower risk of acquisition. The different outcomes between the observational studies and RCTs may be due to a range of known and unknown confounding factors, and differences in the populations considered in the different studies.

Current evidence from RCTs does not support the use of 4CMenB to prevent gonorrhoea in gay and bisexual men at high risk of acquisition. Results from ongoing RCTs will be critical to determine whether vaccine efficacy varies by population or epidemiological context and to inform future gonorrhoea vaccine policy and development.