title: Antibodies against Haemophilus influenzae type b and tetanus in infants after subcutaneous vaccination with PRP-T/diphtheria, or PRP-OMP/diphtheria-tetanus vaccines.
abstract: In an open randomized study, serum antibodies against Haemophilus influenzae type b capsular polysaccharide (PRP) and tetanus toxoid were determined in 146 Swedish infants; 75 of them received PRP conjugated to tetanus toxoid (PRP-T) concurrently with diphtheria toxoid vaccine, and 71 received PRP conjugated to an outer membrane complex of Neisseria meningitidis (PRP-OMP) concurrently with diphtheria-tetanus toxoid vaccine. Injections were given subcutaneously at ages 3, 5 and 12 months. One month after the second injection, the PRP-T recipients had a geometric mean (GM) concentration of 0.38 microgram/ml and only 69% had PRP antibodies > or = 0.15 microgram/ml (considered a protective level). In the PRP-OMP group the GM concentration was 0.44 microgram/ml and 85% had PRP antibodies > or = 0.15 microgram/ml. One month after the third injection, 99% of the infants in both groups had PRP antibodies > or = 0.15 microgram/ml, but PRP-T recipients had significantly higher GM concentration than infants vaccinated with PRP-OMP, 10.21 micrograms/ml vs. 1.90 micrograms/ml (P < 0.001). After all three injections the diphtheria-tetanus toxoid vaccine elicited higher GM concentrations of tetanus toxoid antibodies than did the PRP-T vaccine, but both vaccines induced antibodies above the proposed protective level, 0.01 IU/ml. The reason for the lower than expected immunogenicity of the two Haemophilus influenzae type b conjugate vaccines has yet not been established. For PRP-OMP the most probable explanation is the use of a lot of low immunogenicity, but the route of administration also has to be considered.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Infectious Diseases, University of Göteborg, Sweden.
authors.forename: R M
authors.initials: RM
authors.lastname: Carlsson
authors.forename: B A
authors.initials: BA
authors.lastname: Claesson
authors.forename: S
authors.initials: S
authors.lastname: Iwarson
authors.forename: T
authors.initials: T
authors.lastname: Lagergård
authors.forename: H
authors.initials: H
authors.lastname: Käyhty
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D006192:Haemophilus Infections / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000008:administration & dosage*; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D007279:Injections, Subcutaneous; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage*; D011446:Prospective Studies; D013742:Tetanus / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D013745:Tetanus Toxoid / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D018073:Haemophilus Vaccines; C055753:Haemophilus influenza type b polysaccharide vaccine-tetanus toxin conjugate; C061964:Haemophilus influenzae-type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial; D013745:Tetanus Toxoid