title: Immunologic response to Hib tetanus toxoid conjugated vaccine coadministered with DTPa either mixed or in two separate injections in toddlers not primed with Hib vaccine.
abstract: This open randomized study compared the immunogenicity and safety of a diphtheria-tetanus-acellular pertussis (DTPa) and H. influenzae polyribosylribitol phosphate conjugated to the tetanus toxoid (Hib-PRP-T) vaccine (mixed prior to administration) with separate injections of DTPa and Hib vaccines in toddlers aged two years. A total of 119 children (60 mixed; 59 separate administration), primed with DTPw, but not with Hib vaccine were enrolled. Prior to immunization only 10.3% of toddlers had anti-PRP antibody titres > or =1.0 microg/ml, compared with all children on Days 7 and 30. The anti-PRP and anti-tetanus antibody geometric mean concentrations were lower after the combined DTPa/Hib vaccine compared to separately administered vaccines (47.16 microg/ml vs 78.36 microg/ml and 24.95 IU/ml vs 40.63 IU/ml, respectively). One month after vaccination all children had anti-tetanus and anti-diphtheria antibody titres above the protective level of > or =0.1 IU/ml. The rates of recorded adverse events were similar and mostly mild or moderate in intensity whether the vaccines were combined as a single injection or given separately. We conclude that in 2-year old children, previously not immunized against Hib, a single dose of DTPa and Hib was safe and highly immunogenic irrespective of whether it was given as a combined vaccine or separate injections. Although the increase in anti-T and early (7-10 days after) anti-PRP concentrations was greater when the vaccine components were given separately than after combined administration, the DTPa/Hib combined vaccine would provide an effective method of delivering primary Hib vaccination in unprimed toddlers.
authors.affiliation: Childrens' Clinic of Tartu University Hospital, Estonia. sirli.meriste@kliinikum.ee
authors.forename: Sirli
authors.initials: S
authors.lastname: Meriste
authors.forename: Jeanne-Marie
authors.initials: JM
authors.lastname: Jacquet
authors.forename: Paul
authors.initials: P
authors.lastname: Willems
authors.forename: Irja
authors.initials: I
authors.lastname: Lutsar
mesh_terms: D002675:Child, Preschool; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage / Q000276:immunology*; D006192:Haemophilus Infections / Q000276:immunology* / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000009:adverse effects / Q000276:immunology*; D019741:Haemophilus influenzae type b / Q000276:immunology; D006801:Humans; D012449:Safety; D013745:Tetanus Toxoid / Q000276:immunology; D017778:Vaccines, Combined / Q000009:adverse effects / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; C055753:Haemophilus influenza type b polysaccharide vaccine-tetanus toxin conjugate; D013745:Tetanus Toxoid; D017778:Vaccines, Combined; D018074:Vaccines, Conjugate