Antibody responses to four Haemophilus influenzae type b conjugate vaccines
H. Kayhty, J. Eskola, H. Peltola, P. R. Ronnberg, E. Kela, V. Karanko and L. Saarinen
Department of Bacteriology, National Public Health Institute, Helsinki, Finland.
Serum antibody responses to four Haemophilus influenzae type b capsular
polysaccharide-protein conjugate vaccines (PRP-D, HbOC, C7p, and PRP-T)
were studied and compared in 175 infants, 85 adults and 140 2-year-old
children. Antibodies to the H influenzae type b polysaccharide vaccines
were determined with a Farr-type radioimmunoassay. The infants received two
doses of vaccine at the ages of 4 and 6 months. After the first dose of
vaccine, the geometric mean antibody concentration measured at the age of 6
months was 0.09 to 0.10 mg/L, only marginally higher than that measured
before immunization in all infants who had received PRP-D, HbOC, or C7p but
increased to 0.82 mg/L in those who had received PRP-T. One month after the
second dose, the geometric mean antibody concentration was increased in all
vaccine groups. No significant differences were noted between recipients of
HbOC, C7p, or PRP-T (geometric mean antibody concentrations, 4.32, 3.10,
and 6.10 mg/L, respectively), whereas the PRP-D recipients had a
significantly lower geometric mean antibody concentration (0.63 mg/L). In
contrast, PRP-D, HbOC, C7p, and PRP-T were all highly immunogenic in
adults, with no differences noted among them. The 2-year-old children also
responded to one dose of these vaccines with a high antibody concentration.
