Immunogenicity of Haemophilus influenzae type b polysaccharide-tetanus toxoid conjugate vaccine in infants
S. J. Holmes, B. Fritzell, K. P. Guito, J. F. Esbenshade, M. M. Blatter, K. S. Reisinger, H. L. Keyserling, E. P. Rothstein, H. H. Bernstein, S. Feldman and al. et
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St Louis, Mo 63110.
OBJECTIVE--To compare the safety and immunogenicity of three
investigational lots of Haemophilus influenzae type b
polysaccharide-tetanus toxoid (PRP-T) conjugate vaccine in infants.
DESIGN--A multicenter, randomized immunogenicity trial. Infants were
vaccinated at 2, 4, and 6 months of age with one of three lots of PRP-T. A
control group received H influenzae type b oligomers conjugated to CRM197
(HbOC). Serum was obtained before each injection and 1 month after the
third dose, and assayed blindly for antibody in one laboratory.
SUBJECTS--Four hundred eighty-four infants from private pediatric practices
located in five geographic areas. MEASUREMENTS AND RESULTS--There were no
significant differences in the number of adverse events reported for
infants receiving PRP-T or HbOC, and the rates did not exceed those
observed previously in infants given diphtheria-tetanus-pertussis vaccine
alone. Total serum anti-PRP antibody responses were analyzed in 336 infants
who met strict inclusion criteria. After one, two, or three doses, the
respective antibody responses to each of the three lots of PRP-T and to
HbOC vaccine were similar. The only exception was one lot of PRP-T, which
after one or two injections elicited significantly higher geometric mean
antibody responses than the other two lots or the HbOC vaccine. After a
third injection, there were no significant lot differences. Combining the
data from the different lots, there were no significant differences in the
geometric mean antibody concentration after three doses of PRP-T or HbOC
(8.3 vs 7.7 micrograms/mL), and 95% and 91%, respectively, of infants had
greater than 1.0 microgram/mL of antibody. There were no significant
differences in the magnitudes of the respective IgG1-, IgG2-, and
IgM-specific antibody concentrations between infants given PRP-T or HbOC.
CONCLUSIONS--The three investigational lots of PRP-T tested were safe and
were as immunogenic as or more so than the licensed HbOC conjugate vaccine.
