Article Text
Abstract
Background A New Zealand serogroup B meningococcal epidemic prompted trials of a strain-specific (B:4:P1.7-2,4) outer membrane vesicle vaccine (MeNZB).
Methods Adults, school children, and infants provided serum after three MeNZB doses to evaluate antibody persistence via serum bactericidal assay. Toddler (16–24 months) non-responders and responders received a fourth MeNZB dose 11 and 17 months after dose three respectively. Response was a ≥4-fold rise in bactericidal titre to a titre of ≥8.
Results Geometric mean bactericidal titres (GMTs), with 95% CI, after dose 3: adults: 27 (14–52), 5 (3–11), and 7 (3–15) at 1, 10, and 22 months; school children: 18 (13–25) and 4 (3–6) at 1 and 4 months; infants: 27 (19–39) and 2 (2–3) at 1 and 7 months. The titre achieved after priming significantly influenced persistence. Toddler non-responder GMTs were 4 (3–5) and 1 (1–1) at 1 and 11 months after dose 3 and 69 (46–106) 1 month after dose 4. Responder GMTs were 24 (19–30) and 3 (2–4) at 1 and 17 months after dose 3 and 259 (184–363) 1 month after dose 4. Dose 4 had no safety concerns.
Conclusions Immune response to MeNZB was most sustained in adults. In infants, bactericidal titres decayed almost to baseline by 7 months after dose 3. Toddlers showed marked immune response following a fourth dose suggesting memory. Persisting antibody is likely to be necessary for ongoing protection, as seen with serogroup C meningococci.
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Footnotes
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Funding This study was funded by the New Zealand Ministry of Health and Novartis Vaccines.
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Competing interests DL: funding for travel received from Novartis Vaccines; PO and EY: employed by Novartis Vaccines during the study; DM: serum antibody assays were indirectly funded through a joint contract with the New Zealand Ministry of Health and Novartis Vaccines.
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Ethics approval This study was conducted with the approval of the Auckland Regional Ethics Committee.
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Provenance and peer review Not commissioned; externally peer reviewed.