Presented at the Neonatal Society 2003 Autumn Meeting.
Clarke P1, Ahmad I1, Powell P2, Connell J3, Bedford-Russell A4, Borrow R5, Heath P6, Andrews N7, Southern J7, Miller E7, Robinson M1
1 Neonatal Unit, Hope Hospital, Salford, UK
2 Neonatal Unit, Royal Bolton Hospital, Bolton, UK
3 Neonatal Unit, St Mary’s Hospital, Manchester, UK
4 Neonatal Unit, St George’s Hospital, London, UK
5 PHLS Meningococcal Reference Unit, Withington Hospital, Manchester, UK
6 Department of Child Health and Vaccine Institute, St George’s Hospital, London, UK
7 Immunisation Division, HPA Communicable Disease Surveillance Centre, London, UK
Background: Prematurity and dexamethasone treatment for chronic lung disease are associated with attenuated antibody responses to primary immunisation with several antigens. The duration of immunosuppression may extend into later infancy (1).
Aim: To assess the immune response of preterm infants to a single meningococcal serogroup C conjugate (MCC) immunisation given after infancy.
Methods: A cohort of 49 previously unimmunised toddlers born at less than 33 weeks’ gestation were given a single MCC-CRM197 vaccine at a median age of 13 months. Sera obtained 4 weeks post immunisation were analysed for serum bactericidal antibody (SBA) and serogroup C-specific IgG antibody concentrations. Immune responses of those who previously received dexamethasone in the management of neonatal chronic lung disease were compared with those who had not received dexamethasone. Responses in the study group were also compared with those of an historical group of term infants given a single dose of the same vaccine at 13 months (2). An SBA titre of = 8 was taken to indicate a protective response.
Results: Following a single MCC dose, the IgG antibody geometric mean concentration (GMC) for the cohort was 11.8 (95% confidence interval 8.9-15.6) μg/mL and the SBA geometric mean titre (GMT) for responding infants was 898 (524-1540). For the steroid-treated subgroup the IgG antibody GMC was 16.0 (10.0-25.7) μg/mL and SBA GMT in responders was 2195 (843-5716). Corresponding values for the non steroid-treated subgroup were 10.8 (7.8-15.0) μg/mL and 645 (350-1187) respectively. Overall, 37/48 (77%) of infants achieved a protective SBA titre. Proportions of infants achieving the protective titre did not differ significantly between dexamethasone treated and untreated subgroups (p = 0.42). Compared with the term cohort in whom 64/70 (91%) attained the protective titre, fewer preterm infants were protected (p=0.03).
Conclusions: As a group, children born below 33 weeks’ gestation may be less likely than term infants to mount a satisfactory immune response to a single MCC vaccine dose in the second year of life. Prior dexamethasone treatment given in early infancy does not adversely affect immunogenicity or reduce the likelihood of a protective SBA titre to MCC.
References
1. Clarke P, Powell PJ, Goldblatt D, Robinson MJ. Arch Dis Child Fetal Neonatal Ed.2003;88:F58-F61
2. Richmond P, Borrow R, Goldblatt D, et al J Infect Dis 2001;183:160-163