Antibody persistence in Australian adolescents following meningococcal C conjugate vaccination.
BACKGROUND
In Australia, following the introduction of serogroup C meningococcal (MenC) conjugate vaccine for toddlers and catch-up immunization through adolescence, MenC disease incidence plummeted and remains low. However, individual protection following MenC conjugate vaccination, particularly in young children, may be short-lived. We investigated the persistence of MenC serum bactericidal antibody (SBA) titers in adolescents, more than 7 years after a single "catch-up" dose of MenC conjugate vaccine. We also investigated their exposure and susceptibility to meningococcal serogroups A, W and Y.


METHODS
MenC SBA titers and Men A, C, W and Y IgG geometric mean concentration were measured in 240 healthy 11- to 16-year-old adolescents. The correlate of protection was an rSBA titer of ≥8.


RESULTS
An rSBA≥8 was observed in 105 [44% (95% confidence interval {CI}, 37-50%)] of 240 adolescents (mean age, 13.2 years, mean interval since MenC immunization, 8.2 years). The proportion with an rSBA≥8, geometric mean rSBA titer and geometric mean IgG concentration increased with age, from 22% to 75%, 3.7 to 33.4 and 0.13 to 0.52 μg/mL, in participants who received MenC vaccine at mean age 2.8 to 7.5 years, respectively. Natural acquired antibody to Men A, W and Y was low with IgG geometric mean concentrations of 1.26, 0.38 and 0.47 μg/mL, respectively.


CONCLUSIONS
More than half of Australian adolescents have inadequate serological protection against MenC disease and low natural immunity to MenA, W and Y.
From the *Vaccine and Immunisation Research Group (VIRGo), Murdoch Childrens Research Institute and Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia, †School of Paediatrics and Child Health, University of Western Australia, Telethon Institute for Child Health Research, Princess Margaret Hospital for Children, Perth, Western Australia, Australia; and ‡Vaccine Evaluation Unit, Public Health England, Manchester Royal Infirmary, Manchester, Greater Manchester, United Kingdom.
Kirsten P
KP
Perrett
Peter C
PC
Richmond
Ray
R
Borrow
Terry
T
Nolan
Jodie
J
McVernon
D000293:Adolescent; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology*; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008585:Meningitis, Meningococcal / Q000097:blood / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000276:immunology*; D009345:Neisseria meningitidis / Q000276:immunology*; D062486:Public Health Surveillance; D014611:Vaccination
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine