Response of 7- to 15-month-old infants to sequential immunization with Haemophilus influenzae type b-CRM197 conjugate and polysaccharide vaccines
E. P. Rothstein, R. P. Schiller, J. A. Girone, T. J. Hipp, R. L. Souder, H. H. Bernstein, D. V. Madore, C. L. Johnson and D. H. Smith
Pennridge Pediatrics Associates, Sellersville, PA.
OBJECTIVE. To evaluate the immunologic potential of infants 7 to 15 months
of age to respond to Haemophilus influenzae type b polysaccharide vaccine
following immunization with H influenzae b oligosaccharide-CRM197 conjugate
vaccine. STUDY DESIGN. One hundred seventy-one infants, aged 7 to 15
months, were consecutively and alternatively assigned to one of three
immunization protocols. Group 1 (n = 71) received three doses of H
influenzae b oligosaccharide-CRM197 conjugate vaccine, group 2 (n = 47)
received two doses of H influenzae b oligosaccharide-CRM197 conjugate
vaccine followed by one dose of H influenzae type b polysaccharide vaccine,
and group 3 received one dose of H influenzae b oligosaccharide-CRM197
conjugate vaccine followed by two doses of H influenzae type b
polysaccharide vaccine. Immunizations were given on day 0 and at 2 months
and 6 months. Anti-H influenzae type b polysaccharide antibody levels were
measured on day 0 and 2, 3, 6, 7, and 12 months after the study began.
RESULTS. Haemophilus influenzae type b polysaccharide vaccine given as a
second dose stimulated an antibody rise but did so less effectively than H
influenzae b oligosaccharide-CRM197 conjugate vaccine. Two doses of H
influenzae b oligosaccharide-CRM197 conjugate vaccine were highly
immunogenic; geometric means were 31 and 35 micrograms/mL in the 7- to
11-month and 12- to 15-month age groups, respectively. Following two doses
of H influenzae b oligosaccharide-CRM197 conjugate vaccine, both
immunization protocols resulted in (1) equally high geometric mean antibody
levels 1 month after immunization and (2) similar geometric mean antibody
levels 6 months after immunization. CONCLUSIONS. Haemophilus influenzae b
oligosaccharide-CRM197 conjugate vaccine induces antibody levels that would
be expected to protect infants from initial invasion and primes the immune
system for an anamnestic response. Our data indicate that if a booster
immunization is needed, H influenzae type b polysaccharide vaccine could be
an alternative to H influenzae b oligosaccharide-CRM197 conjugate vaccine.
