IMMUNOGLOBULIN DEFICIENCY IN CHILDREN WITH HIB VACCINE FAILURE
Dr. Clarissa Oeser
United Kingdom 
11 slide(s) – English – 2011-06-07
Background:
Immunoglobulin (Ig) deficiency in children with Hib vaccine failure is well-described, but its clinical significance is unknown.
Aims:
To estimate the prevalence of Ig deficiency in children with Hib vaccine failure several years after infection and to determine their risk of recurrent infections
Methods
Children who developed invasive Hib disease after immunization with Hib conjugate vaccine from 1992 to 2006 were identified through national surveillance. Participation involved completion of a questionnaire and a blood sample from the child.
Results
A completed questionnaire and blood sample was provided by 170 children at a median of 4 years after infection, equivalent to 1035 child-years of follow-up. Ig deficiency was present in 11.2% and was associated with age <2 years at onset of Hib disease (63.2% vs. 39.7%, P=0.05) and receiving at least two antibiotic courses/year in early childhood (57.9% vs. 25.8%, P=0.004), but not with clinical presentation, severity of Hib infection or risk of other serious infections requiring hospitalization. In a logistic regression model, antibiotic use was independently associated with presence of an underlying medical condition (OR=7.3; 95% CI=2.3-22.7; P=0.001) and Ig deficiency (OR=5.4; 95%CI=1.8-16.0; P=0.003), while breastfeeding was protective (OR=0.30; 95%CI=0.14-0.65; P=0.002).
Conclusions
At 4 years after infection, the prevalence of Ig deficiency in children with Hib vaccine failure is half that reported in the first few months after Hib infection. Young children with Hib vaccine failure may have quantitative as well as qualitative antibody defects, which predisposes them to recurrent minor and occasionally serious infections, but improves with age.
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