Responses to immunisation with Hib conjugate vaccine in Australian breastfed and formula-fed infants.
OBJECTIVE
There are conflicting reports as to whether breastfed infants respond with higher antibody levels to conjugate Haemophilus influenzae type b (Hib) vaccine compared with formula-fed infants. These observations prompted us to investigate the effect of feeding method on the antibody concentration to Hib polyribosylribitol (PRP) both prior to and 3 months after the primary course of immunisation with Hib (PRP-OMP).


METHODS
We measured plasma concentrations of IgG antibody to Hib PRP by enzyme-linked immunosorbent assay in blood samples from a total of 272 breastfed and formula-fed infants prior to immunisation (7 weeks of age, n = 82 and n = 148, respectively) and again 3 months after completion of the primary course of immunisation with Hib PRP-OMP (7 months of age, n = 88 and n = 132, respectively).


RESULTS
Breastfeeding was associated with lower plasma antibody titres at both times (P < 0.01, T-test) with 49% of breastfed infants having anti-PRP concentrations below 1.0 microg/mL at age 7 months. There was no reported invasive Hib disease in this cohort of infants, and nationally the effectiveness of the Hib vaccination programme remains high.


CONCLUSIONS
These data suggest that breastfeeding may be associated with immunomodulation of infant Hib immunisation responses with this immunisation regime. Further research is needed to determine whether differences in antibody concentration described here are primarily determined by factors directly attributed to breastfeeding or whether other environmental factors may play a significant role.
Hawkes
Joanna S
JS
Child Health Research Institute, Flinders Medical Centre and Flinders University, Bedford Park, South Australia, Australia.
Makrides
Maria
M
Roberton
Donal M
DM
Gibson
Robert A
RA
D000914:Antibodies, Viral / Q000097:blood*; D001315:Australia; D016667:Bacterial Capsules; D001942:Breast Feeding; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000276:immunology*; D006761:Hospitals; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D007225:Infant Food; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000008:administration & dosage
D000914:Antibodies, Viral; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial; D018074:Vaccines, Conjugate