Phase II meningococcal B vesicle vaccine trial in New Zealand infants.

BACKGROUND: A tailor-made serogroup B outer membrane vesicle vaccine was evaluated in the context of a serogroup B meningococcal epidemic dominated by Neisseria meningitidis strain B:4:P1.7b,4. OBJECTIVE: To determine the safety, reactogenicity and immunogenicity in infants aged 6-8 months of a meningococcal B vaccine developed against the New Zealand epidemic strain. DESIGN, SETTING AND PARTICIPANTS: Observer-blind, randomised, controlled trial conducted in 296 healthy infants in Auckland, New Zealand. INTERVENTION: Infants were randomised 4:1 to receive three doses of New Zealand candidate vaccine (epidemic strain NZ98/254, B:4:P1.7b,4) or meningococcal C conjugate vaccine at 6-weekly intervals. MAIN OUTCOME MEASURES: Immune response was determined by human complement mediated serum bactericidal assay. Sero-response was a fourfold or greater rise in titre compared to baseline, with baseline titres <4 required to increase to >or=8. Blood samples were taken before vaccination, 6 weeks after dose two, and 4 weeks after dose three. Local and systemic reactions were recorded for 7 days following vaccination. RESULTS: Sero-response to the candidate vaccine strain, NZ98/254, was demonstrated in 74% of vaccinees (95% CI: 68% to 80% intention-to-treat; 67% to 79% per protocol) after three doses of New Zealand candidate vaccine. No meningococcal C conjugate vaccine recipients were sero-responders to NZ98/254 after three doses. Both vaccines were well tolerated with no vaccine related serious adverse events. CONCLUSIONS: Our data indicate that the New Zealand candidate vaccine administered in three doses to this group of 6-8-month-old infants was safe and immunogenic against the candidate vaccine strain NZ98/254 (Neisseria meningitidis B:4:P1.7b,4).