Immune memory in children previously vaccinated with an experimental quadrivalent meningococcal polysaccharide diphtheria toxoid conjugate vaccine.
BACKGROUND
In a previous study, a meningococcal diphtheria toxoid conjugate vaccine (MCV-4) triggered robust bactericidal antibody responses against serogroups A, C, Y, and W-135 in 2- to 10-year-old children. A subset of participants, 2 to 3 years of age at the initial vaccination, was evaluated for persistence of antibody, immune memory, and antibody avidity.


METHODS
Participants were healthy children vaccinated 23 to 36 months earlier with MCV-4 (primed) or newly recruited meningococcal vaccine-naive 4-year-olds. Participants in both groups were alternately allocated to provide sera 8 or 28 days after administration of one tenth of the recommended dose of a meningococcal polysaccharide vaccine (PSV-4). Immune responses were assessed in sera obtained at baseline and either 8 or 28 days after reduced-dose PSV-4 administration. Safety was monitored.


RESULTS
Before PSV-4 challenge, serum bactericidal antibody geometric mean titers (SBA GMTs) were higher for all 4 serogroups in the MCV-4-primed group than in the vaccine-naive group. SBA GMTs, geometric mean concentrations of immunoglobulin G (IgG) and geometric mean avidity indices for all 4 serogroups were significantly higher among MCV-4-primed versus vaccine-naive participants in the cohorts evaluated at 8 or 28 days after PSV-4 challenge. Adverse events were generally mild, self-limited, and comparable in all groups of children.


CONCLUSIONS
Persistence of bactericidal antibody was seen for 23 to 36 months after a primary dose of MCV-4 in young children. Booster responses and avidity maturation were evident after a challenge with reduced-dose polysaccharide vaccine.
Pichichero
Michael
M
University of Rochester, Rochester, NY, USA. michael_pichichero.edu
Papa
Thomas
T
Blatter
Mark
M
Mitchell
Douglas
D
Kratz
Richard
R
Sneed
Jane
J
Bassily
Ehab
E
Casey
Janet
J
Gilmet
Gregory
G
D000907:Antibodies, Bacterial / Q000097:blood; D000915:Antibody Affinity; D001770:Blood Bactericidal Activity; D002675:Child, Preschool; D004168:Diphtheria Toxoid / Q000276:immunology*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007156:Immunologic Memory; D008297:Male; D008589:Meningococcal Infections / Q000517:prevention & control; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000276:immunology; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
D000907:Antibodies, Bacterial; D004168:Diphtheria Toxoid; D007070:Immunoglobulin A; D022401:Meningococcal Vaccines; D011135:Polysaccharides, Bacterial; D018074:Vaccines, Conjugate