The B-cell response to a primary and booster course of MenACWY-CRM197 vaccine administered at 2, 4 and 12 months of age.

A quadrivalent meningococcal vaccine conjugated to CRM197 (MenACWY-CRM197) is immunogenic in young infants. We assessed the memory B-cell and antibody responses after a primary and booster course of MenACWY-CRM197 in children. At 5 months of age, following primary immunisation, serogroup-specific memory B-cells were detectable in fewer than 25% of children, although protective antibody titres (hSBA ≥ 4) were detectable in 69% of children against serogroup A and more than 95% against the other serogroups. At 12 months, before booster immunisation the percentages with hSBA ≥ 4 were 5% for serogroup A, and between 44 and 70% for the other serogroups. One month after booster immunisation with MenACWY-CRM197 over 50% of children had detectable memory B-cells, and 91% had hSBA ≥ 4 against serogroup A and more than 99% against the other serogroups. These data show that few antigen-specific anticapsular memory B-cells can be detected after two-doses priming with MenACWY-CRM197. For MenC and CRM197, the antigens with the highest number of B-cells at 5 months, there was a definite (p ≤0 .02) but weak correlation with antibody persistence at 12 months. Although previous studies suggest that measuring memory B-cell responses after priming immunisations in infancy can be used to predict antibody persistence and memory responses, this may not be suitable for all antigens in young children.

Immunogenicity and reactogenicity of a 13-valent-pneumococcal conjugate vaccine administered at 2, 4, and 12 months of age: a double-blind randomized active-controlled trial.

BACKGROUND: A 2-, 4-, and 12-month schedule of a novel 13-valent-pneumococcal conjugate vaccine (PCV13), containing serotype 1, 3, 4, 5, 6A, 6B 7F, 9V, 14, 18C, 19A, 19F, and 23F polysaccharides individually conjugated to CRM197 was evaluated in a randomized, double-blind, controlled infant study. METHODS: Two hundred eighty-six healthy infants received PCV13 or the 7-valent-pneumococcal conjugate vaccine (PCV7) at 2, 4, and 12 months of age, alongside a serogroup C meningococcal (MenC) vaccine (2 and 4 months of age), DTaP-IPV-Hib (2, 3, and 4 months), and a Hib-MenC vaccine (12 months). Specific antibody responses were assessed at age 5, 12, and 13 months. RESULTS: At 13 months of age, >97% of PCV13 recipients had pneumococcal serotype-specific serum IgG concentrations ≥0.35 µg/mL for each vaccine serotype except serotype 3 (88.2%), and at least 93% of PCV13 recipients had OPA titers ≥1:8 for each serotype. At 5 months, 110/114 (96.5%) of PCV13 recipients and 100/102 (98.0%) of PCV7 recipients had serum anti-PRP (Hib) IgG concentration ≥0.15 µg/mL (difference, 1.5%; CI, -7.1%­3.7%), while 119/120 (99.2%) and 117/118 (99.2%), respectively, had MenC serum bactericidal assay titers of ≥1:8. All PCV13 recipients and 110/113 (97.3%) of PCV7 recipients had IgG concentrations against fimbrial agglutinogens of ≥2.2 EU/mL; IgG concentrations for the remaining pertussis antigens were ≥5 EU/mL for all participants. Local reactions and systemic events were similar in the PCV13 and PCV7 groups. CONCLUSIONS: A 2-, 4-, and 12-month course of PCV13 was immunogenic for all 13 vaccine serotypes and was well tolerated.