Reactogenicity of DTPa-HBV/Hib vaccine administered as a single injection vs DTPa-HBV and Hib vaccines administered simultaneously at separate sites, to infants at 2, 4 and 6 months of age.

An open, randomised, multicentre trial was performed to assess the reactogenicity and safety profile of the administration of a candidate Haemophilus influenzae type b (Hib) conjugate vaccine with a quadrivalent diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine as a single injection (Group 1) versus the simultaneous administration of the latter vaccine (DTPa-HBV) and an available Hib conjugate vaccine (Group 2) in opposite thighs, as a primary vaccination course to healthy infants at 2, 4 and 6 months of age. Eight hundred and eighty five infants (9.3+/-1.4 weeks old) were randomly allocated to Group 1 (n=665) and Group 2 (n=221). Oral polio vaccine was given concomitantly to all subjects. Blood samples (pre-vaccination and 1 month after the third dose) were obtained from a subset of infants (Group 1, 73; Group 2, 22) for serological determinations. Local and general symptoms were recorded by parents on diary cards. 2614 diary cards (Group 1, 1966; Group 2, 648) were collected. There were no statistically significant differences in the incidence of local and general symptoms between groups. Pain such that the infant cried when limb was moved was reported in 0.6 and 0.2% in groups 1 and 2, respectively. Redness and swelling (>20 mm in diameter) were recorded between 2.1 and 3% in both groups. Fussiness preventing normal activities was the most frequently reported general symptom in both groups (1.6 and 1.9% in groups 1 and 2, respectively). Fever (rectal temperature >39.5 degrees C) was reported in 0.4% (Group 1) and 0.3% (Group 2). All subjects included in the immunogenicity analysis had seroprotective or seropositive titres to the diphtheria, tetanus, hepatitis B and pertussis components of the vaccines. About 99 and 100% of infants had anti-PRP titres > or =0.15 mcg/ml in groups 1 and 2, respectively. This study indicates that DTPa-HBV vaccine given in a single injection with a candidate Hib conjugate vaccine has a similar reactogenicity profile to that of two commercially available vaccines (DTPa-HBV, Hib) given in two simultaneous injections to infants 2, 4 and 6 months of age.