Persistence of antibody and booster responses to reimmunization with Haemophilus influenzae type b polysaccharide and polysaccharide diphtheria toxoid conjugate vaccines in children initially immunized at 15 to 24 months of age.
To evaluate the persistence of antibody after Haemophilus influenzae type b polysaccharide vaccine (PRP) and H influenzae type b polysaccharide diphtheria toxoid conjugate vaccine (PRP-D), a group of 141 infants initially immunized between 15 and 24 months of age were studied 1 year later. One month after immunization with PRP, the man anti-PRP antibody level was 0.27 microgram/mL and 1 year later was 0.29 microgram/mL (not significant). In the group immunized with PRP-D, the levels were 1.34 micrograms/mL and 1.20 micrograms/mL (not significant), respectively. To evaluate immunogenicity and safety of a booster immunization 1 year after initial vaccination, subjects were randomly assigned to receive saline, PRP, or PRP-D. In addition, 73 age-matched previously unimmunized subjects were vaccinated with PRP or PRP-D. In all groups, adverse reactions were minor and resolved by 48 hours. Subjects receiving booster immunization with PRP or PRP-D had significantly greater antibody responses than children of the same age receiving their first dose of vaccine. The highest antibody levels were achieved in children initially immunized with PRP-D, regardless of whether the booster vaccine was PRP (112.8 micrograms/mL) or PRP-D (122.0 micrograms/mL) (not significant). Antibody levels after booster vaccine were significantly lower in those initially given PRP compared with those initially given PRP-D but significantly higher than in age-matched previously unimmunized control subjects (PRP booster 3.16 micrograms/mL vs control of 0.62 microgram/mL [P less than .05]; PRP-D booster 12.31 micrograms/mL vs control 2.31 micrograms/mL [P less than .01]).
Berkowitz
C D
CD
Harbor/UCLA Medical Center, Torrance 90509.
Ward
J I
JI
Chiu
C E
CE
Marcy
S M
SM
Gordon
L
L
Hendley
J O
JO
Meier
K
K
Marchant
C D
CD
McVerry
P
P
D000917:Antibody Formation; D016667:Bacterial Capsules; D001428:Bacterial Vaccines / Q000276:immunology*; D002675:Child, Preschool; D004168:Diphtheria Toxoid / Q000276:immunology*; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary; D007223:Infant; D011135:Polysaccharides, 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