Progress in genomic sequencing and bioinformatic analysis, has opened a new era in vaccine design enabling the discovery of many new antigen candidates. This approach has successfully applied to Neisseria meningitidis serogroup B (MenB), a life-threatening disease with a high case-fatality rate and an unpredictable epidemiology due to strain evolution and outbreak potential. 4CMenB is the only licensed MenB vaccine providing protection in infants and adolescents and now approved in over 50 countries. It comprises Neisseria adhesin A (NadA), factor H binding protein (fHbp), Neisserial Heparin Binding Antigen (NHBA), and outer membrane vesicles (OMVs) expressing PorA P1.4. These components elicit broad and synergistic bactericidal antibody responses. Notably, some of these antigens are also conserved in non-B meningococcal serogroups and Neisseria gonorrhoeae, inducing cross-protection. To further elucidate the protective mechanism of the 4CMenB antigens, we isolated human monoclonal antibodies (HumAbs) from vaccinated individuals. These antibodies were screened for their binding affinity to MenB antigens and Neisseria gonorrhoeae enabling the characterization of the immune response, the identification of the most protective epitopes and the determination of OMV antigens contributing to protection. By integrating genome-driven antigen discovery with monoclonal antibody characterization, we can accelerate the development of next-generation vaccines targeting complex bacterial pathogens, transforming infectious disease prevention and treatment.