Persistence of immunity following a booster dose of Haemophilus influenzae type B-Meningococcal serogroup C glycoconjugate vaccine: follow-up of a randomized controlled trial.
BACKGROUND
Antibodies against Haemophilus influenzae type b (Hib) and serogroup C Neisseria meningitidis (MenC) wane after early infant immunization.


METHODS
Children previously immunized in a randomized controlled trial at ages 2, 3, and 4 months with DTPa-IPV-Hib and MenC-CRM197 (MenC-CRM group) or DTPa-IPV and Hib-MenC-TT (Hib-MenC-TT group) had blood samples drawn at 1 and 2 years following a booster dose of Hib-MenC-TT at 12 to 15 months of age. A blood sample was also drawn at the year 2 follow-up from a separately recruited age-matched control group who had not received a booster.


RESULTS
In 271 children at year 1, mean 14.6 months (range: 12-18 months) following the Hib-MenC-TT booster, MenC bactericidal titers above the protective threshold (rSBA ≥ 1:8) was demonstrated in 89.0% of the Hib-MenC-TT group and 69.5% of MenC-CRM participants. Antipolyribosylribitol phosphate Ig ≥ 1.0 μg/mL (Hib correlate for long-term protection) was seen in 94.9% and 82.5%, respectively.In 379 participants (including 72 control children) at year 2 (age: 39-43 months, 25-31 months post Hib-MenC-TT) persistence of MenC antibodies was demonstrated in 67.1% of the Hib-MenC-TT group and 40.5% of the MenC-CRM group, compared with 44.1% of control group participants. Antipolyribosylribitol phosphate Ig ≥ 1.0 μg/mL was seen in 89.0%, 74.7%, and 38.9%, respectively.


CONCLUSIONS
A toddler Hib-MenC-TT booster helps sustain immunity against Hib to 3½ years of age. Persistence of MenC antibody is similar in children primed with MenC-CRM197 in infancy who receive a booster Hib-MenC-TT, to those who receive no booster. Persistence of MenC antibody is better when primed and boosted with Hib-MenC-TT.
Khatami
Ameneh
A
Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK. ameneh.khatami@paediatrics.ox.ac.uk
Snape
Matthew D
MD
John
Tessa
T
Westcar
Sharon
S
Klinger
Chaam
C
Rollinson
Llinos
L
Boutriau
Dominique
D
Mesaros
Narcisa
N
Wysocki
Jacek
J
Galaj
Andrzej
A
Yu
Ly-Mee
LM
Pollard
Andrew J
AJ
D000907:Antibodies, Bacterial / Q000097:blood*; D016667:Bacterial Capsules / Q000008:administration & dosage* / Q000276:immunology*; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D018073:Haemophilus Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D013997:Time Factors
D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine