One or two doses of quadrivalent meningococcal serogroups A, C, W-135 and Y tetanus toxoid conjugate vaccine is immunogenic in 9- to 12-month-old children.
BACKGROUND
The incidence of invasive meningococcal disease is highest in infants. A quadrivalent meningococcal serogroups A, C, W-135 and Y tetanus toxoid conjugate vaccine (MenACWY-TT) was evaluated in children 9-12 months of age.


METHODS
We randomized infants (1:1) to receive 1 dose of MenACWY-TT at 12 months of age (ACWY-1 group) or 2 doses at 9 and 12 months (ACWY-2). We measured immunogenicity after each dose and 1 year after completing vaccination using human serum bactericidal antibody (hSBA) assays according to prespecified criteria of ≥ 1:8. Local and general symptoms were solicited for 8 days after vaccination. Adverse events were recorded for 6 months after the last dose.


RESULTS
We enrolled and vaccinated 349 subjects, of whom 248 reenrolled at Year 1 for evaluation of antibody persistence. Percentages of subjects with postvaccination hSBA ≥ 1:8 in the ACWY-1 group were 79.5%, 94.6%, 50.8% and 56.1% and in the 2-dose group (ACWY-2) were 88.4%, 100%, 99.3% and 99.3% postdose 2 for serogroups A, C, W-135 and Y, respectively. At Year 1, 80.0-99.1% in each group had hSBA ≥ 1:8, except for serogroup A, for which 20.6% (ACWY-1) and 25.9% (ACWY-2) retained hSBA ≥1:8. Both schedules were well-tolerated, with no observed increase in reactogenicity after the second dose.


CONCLUSIONS
MenACWY-TT was immunogenic when administered as a single dose at 12 months of age, or as 2 doses at 9 and 12 months, and had a clinically acceptable safety profile. Good antibody persistence was observed through 12 months postvaccination after both treatment schedules for serogroups C, W-135, Y.
Kaiser Permanente Vaccine Study Center, Oakland, CA 94612, USA. nicola.klein@kp.org
Nicola P
NP
Klein
Yaela
Y
Baine
Veronique
V
Bianco
Pascal R
PR
Lestrate
Aftab
A
Naz
Mark
M
Blatter
Leonard R
LR
Friedland
Jacqueline M
JM
Miller
D000907:Antibodies, Bacterial / Q000097:blood; D001770:Blood Bactericidal Activity; D002675:Child, Preschool; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D007156:Immunologic Memory; D007223:Infant; D008297:Male; D008589:Meningococcal Infections / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology*; D013997:Time Factors; D014611:Vaccination / Q000009:adverse effects / Q000379:methods*
D000907:Antibodies, Bacterial; D022401:Meningococcal Vaccines; C576777:tetravalent meningococcal serogroups A, C, W-135 and Y tetanus toxoid conjugate vaccine