Interchangeability of conjugated Haemophilus influenzae type b vaccines in infants
E. L. Anderson, M. D. Decker, J. A. Englund, K. M. Edwards, P. Anderson, P. McInnes and R. B. Belshe
Department of Medicine, Saint Louis (Mo) University School of Medicine.
OBJECTIVE--To evaluate the safety and immunogenicity of two Haemophilus
influenzae type b (Hib) conjugate vaccines when administered in serial
combination. These vaccines consisted of Hib capsular polysaccharide
polyribosyl-ribitol phosphate (PRP) conjugated to the meningococcal outer
membrane protein (OMP) complex (PRP-OMP) and H influenzae oligosaccharide
conjugated to a mutant toxin (CRM197) isolated from Corynebacterium
diphtheriae (HbOC). DESIGN--Randomized, double-blind, clinical trial
evaluating five Hib vaccination regimens. SETTING--Vaccine Treatment and
Evaluation Units and affiliated private pediatric practices at Saint Louis
(Mo) University, Vanderbilt University, Nashville, Tenn, and Baylor College
of Medicine, Houston, Tex. PATIENTS--A total of 497 healthy 2-month-old
infants scheduled to receive routine immunization.
INTERVENTION--Participants received either PRP-OMP or HbOC given as
recommended by the manufacturer, PRP-OMP at 2 and 6 months, HbOC at 2
months, then PRP-OMP at 4 and 6 months, or PRP-OMP at 2 months and then
HbOC at 4 and 6 months. Unconjugated PRP was given at 15 months to evaluate
priming. RESULTS--Geometric mean antibody concentrations differed
significantly among the groups following the second and third immunizations
of the primary series and following booster immunization with unconjugated
PRP. On each occasion, the groups receiving serial combinations of PRP-OMP
and HbOC achieved mean antibody concentrations that equalled or exceeded
those of the groups receiving a single product. Adverse reactions did not
vary by group. CONCLUSIONS--The studied sequential combinations of Hib
vaccines were safe and at least as immunogenic as either vaccine alone.
