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

Sirli Meriste, Jeanne-Marie Jacquet, Paul Willems and Irja Lutsar

volume 4 | issue 1

january/february 2008
Pages: 31 - 35

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This open randomised 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 ≥1.0 μg/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 μg/ml vs 78.36 μg/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 ≥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 immunised 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

Sirli Meriste

Childrens%u2019 Clinic of Tartu University Hospital, Tartu, Estonia

Jeanne-Marie Jacquet

GlaxoSmithKline Biologicals, Rixensart, Belgium

Paul Willems