Decline in serum antibody to the capsule of Haemophilus influenzae type b in the immediate postimmunization period.
OBJECTIVE
To determine what change, if any, occurs in the serum anticapsular antibody concentration immediately after immunization with either Haemophilus influenzae type b capsular polysaccharide vaccine (PRP) or a vaccine consisting of the capsular polysaccharide conjugated to diphtheria toxoid (PRP-D).


METHODS
Children: a convenience sample of 32 healthy 2-year-old children from diverse locales. Adults: a convenience sample of 16 healthy adults chosen from employees at the Washington University and Tulane University schools of medicine.


METHODS
PRP or PRP-D vaccine administered to the adults and serum obtained daily for 5 days. PRP vaccine was administered to the children, and serum was sampled 2 or 3 days or 4 or 5 days after immunization, or both.


RESULTS
Decline in serum antibody in all seven (100%) adult recipients of PRP. The nadir occurred on days 1 to 3, and the decrease average 26.0% of the preimmunization concentration. Eight (89%) of nine PRP-D recipients had a similar decline that averaged 25.9%. Of 29 children, 20 (69%) had a decline that averaged 14.7%. The magnitude of anticapsular antibody present before immunization was correlated with the magnitude of the observed decrease.


CONCLUSIONS
A decrease in serum anticapsular antibody occurs in most children and adults immunized with PRP (adults and children) or PRP-D (adults). Such a decrease might transiently increase the risk of invasive disease if it occurred during a period of asymptomatic colonization with H. influenzae type b.
Daum
R S
RS
Department of Pediatrics, Tulane University School of Medicine, New Orleans.
Sood
S K
SK
Osterholm
M T
MT
Pramberg
J C
JC
Granoff
P D
PD
White
K E
KE
Granoff
D M
DM
D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D016667:Bacterial Capsules; D001428:Bacterial Vaccines / Q000276:immunology*; D002675:Child, Preschool; D004168:Diphtheria Toxoid / Q000276:immunology*; D004198:Disease Susceptibility / Q000276:immunology; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007114:Immunization; D007223:Infant; D011135:Polysaccharides, Bacterial / Q000276:immunology; D013997:Time Factors
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D004168:Diphtheria Toxoid; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; C052180:Haemophilus influenzae type b-polysaccharide vaccine-diphtheria toxoid conjugate; D011135:Polysaccharides, Bacterial