Poster Presentations

Session Title: VACCINE AND PREVENTION

CELLULAR AND HUMORAL IMMUNE RESPONSES OF PRE-TERM INFANTS TO THE PRIMING WITH PERTUSSIS VACCINES

F. Vermeulen¹, V. Verscheure², E. Damis³, D. Vermeylen⁴, G. Leloux², V. Dirix², C. Locht⁵, F. Mascart^2
1Pediatrics, ²Laboratory of Vaccinology and Mucosal Immunity, Hôpital Erasme - Université Libre de Bruxelles (ULB), ³Pediatric Department, Centre Hospitalier Inter Régional Edith Cavell, ⁴Neonatal Intensive Care Unit, Hôpital Erasme - Université Libre de Bruxelles (ULB), Bruxelles, Belgium, ⁵INSERM U629, Institut Pasteur de Lille, Lille, France

Background and aims: As protection against Bordetella pertussis is mediated by both specific antibody and T cell responses, and as it is recommended to vaccinate preterm infants against B. pertussis according to chronological age, we have determined whether highly pre-term infants (≤ 30 weeks) are able to mount these immune responses during vaccine priming.
Methods: 46 premature infants were vaccinated at 2, 3 and 4 months of chronological age with a Tetravalent diphtheria-tetanus-pertussis-polio vaccine mixed with an Haemophilus influenzae Type b vaccine. 22 received an acellular (Pa), and 24 received a whole cell (Pw) pertussis vaccine. Blood samples collected at 2, 3 and 6 months of age were analyzed for specific IgG titers and avidities, as well as for antigen-induced IFN-γ, IL-5 and IL-13 secretions.
Results: In Pa-vaccinated infants, anti-filamentous haemagglutinin and anti-pertusiss toxin IgG were detected in the sera from 6 months-old infants at similar titres and nearly same avidities as age-matched vaccinated full-term infants. Most of the Pa- or Pw-vaccinated infants developed at 3 or 6 months of age an IFN-γ response to the B. pertussis antigens, accompanied by an IL-5 and IL-13 secretion for the Pa-vaccinated infants.
Conclusions: Like full-term infants, most pre-term infants are able to mount at 6 months of age adequate specific humoral and cellular immune responses to the administration of prime pertussis vaccination at chronological age. However, since most severe cases of infection occur before 2 months of age, additional efforts should be made to protect infants already at birth against B. pertussis.