Immunogenicity and reactogenicity of a pneumococcal conjugate vaccine administered combined with a Haemophilus influenzae type b conjugate vaccine inUnited Kingdom infants

Background, Streptococcus pneumoniae is a major disease burden in young chi ldren and the incidence of antibiotic-resistant pneumococcal strains is inc reasing. Multivalent pneumococcal saccharide-protein conjugate vaccines hav e recently been developed. Objectives. To assess the immunogenicity and reactogenicity of a 7-valent p neumococcal conjugate vaccine (7VPnC) administered as a separate injection or as a combined injection with Haemophilus influenzae type b vaccine (HbOC ) at 2, 3 and 4 months of age. Methods. Randomized controlled trial of 368 healthy UR infants receiving ro utine vaccines only (control group), routine vaccines and 7VPnC as a separa te injection (separate group), or routine vaccines and 7VPnC combined with HbOC (combined group) at 2, 3 and 4 months. The control group received 7VPn C at 5, 6 and 7 months. All groups received pneumococcal polysaccharide vac cine at 13 to 16 months. Anticapsular IgG antibodies to 7VPnC serotypes wer e measured at 2, 5, 13 and 14 months and safety data collected. Results, IgG antibody concentrations at 5 months were higher in the two tre atment groups compared with the controls for all 7VPnC serotypes (P < 0.001 ) and higher in the separate group than the combined group for five 7VPnC s erotypes (P < 0.05), For both treatment groups antibody concentrations were higher at 14 months (range, 6.6 to 25.3 mu g/ml) than at 5 months (range, 0.6 to 2.5 mu g/ml) for all 7VPnC serotypes (P < 0.001), Conclusion, 7VPnC was well-tolerated, safe and immunogenic when administere d as a separate or as a combined 7VPnC/HbOC injection, Although antibody re sponses were lower in the infants who received the combination compared wit h those who received 7VPnC as a separate injection, marked anamnestic respo nses to polysaccharide challenge were observed, suggesting that both groups were immunologically primed.