Epidemics of serogroup B meningococcal disease are rare. Strain-specific outer membrane vesicle vaccines, which are not marketed, are the only current tool for control. A correlate of protection is ill defined, but published data suggest that measured serum bactericidal antibody levels parallel efficacy. Even infants can mount a strain-specific antibody response to a strain-specific vaccine. New Zealand's epidemic (1991-2007; peak rate [in 2001], 17.4 cases per 100,000 persons) was dominated by a single strain. After a 5-year search (1996-2001) for a manufacturer for a strain-specific outer membrane vesicle vaccine, a fast-tracked research program (2002-2004) determined the safety and immunogenicity of vaccine in infants (2 age groups: 6-10 weeks and 6-8 months), children (age, 16-24 months), and school-aged children (age, 8-12 years) after an adult trial. The vaccine was reactogenic, compared with control vaccines (meningococcal C conjugate and routine infant vaccines), but retention was high. Three vaccine doses produced antibody levels (measured by serum bactericidal assay) that were considered to be adequate for public health intervention. However, in young infants, a fourth dose was required to achieve levels equivalent to those achieved by other age groups. Provisional licensure by New Zealand's MedSafe was based on serological criteria strengthened by bridged safety data from studies of the parent outer membrane vesicle vaccine, independent assessment of manufacturing quality, and a clear plan for safety monitoring and effectiveness evaluation after licensure.