Immunogenicity and Tolerability in Infants of a New Zealand Epidemic Strain Meningococcal B Outer Membrane Vesicle Vaccine

Background: An outer membrane vesicle meningococcal vaccine (MeNZB), was developed for the New Zealand epidemic strain of Neisseria meningitidis B:4:P1.7-2,4. Methods: A phase II, randomized, observer blind, controlled study evaluating the safety, reactogenicity, and immunogenicity of McNZB administered with routine New Zealand immunizations at 6 weeks, 3 months, and 5 months of age (n = 375). Group 1 (n = 250) received 25 mu g MeNZB and routine immunizations with a fourth MeNZB dose given at 10 months (n = 51). Group 2 (n = 125) received routine immunizations only. Sero-response was a >= 4-fold rise in vaccine strain serum bactericidal antibody titer compared with baseline or a titer of at least 1 :8 for baselines <1:4. Reactogenicity was monitored for 7 days after vaccination. Results: Sero-response in Group 1 was achieved in 53% (95% Confidence interval [CI]: 46-59, n = 239) and 69% (95% CI: 54-80, n = 45) with geometric mean antibody titers of 9 (95% CI: 7-10) and 22 (95% CI: 12-39) after the third and fourth doses, respectively. No negative interference by MeNZB on routine immunizations was detected. There were no serious adverse events judged to be vaccine related. Conclusions: In this group of New Zealand infants, 4 MeNZB doses were required to demonstrate titers comparable with those achieved after 3 doses in older children. MeNZB was safe when used concomitantly with routine New Zealand immunizations to 5 months of age.