AGE-RELATED IMMUNOGENICITY OF MENINGOCOCCAL POLYSACCHARIDE VACCINE INABORIGINAL CHILDREN AND ADOLESCENTS LIVING IN A NORTHERN MANITOBA RESERVE COMMUNITY

Objective, To determine the total and functional serogroup C antibody response to a quadrivalent meningococcal polysaccharide vaccine in a g roup of aboriginal infants, children and adolescents. A secondary obje ctive was to determine their prevalence of meningococcal carriage. Des ign, Open prospective, before and after intervention study. Subjects,A boriginal children ages 0.5 to 19.9 years, living in a single Northern community and eligible for a public health immunization campaign cond ucted in all Manitoba native reserve communities to control a meningoc occal serogroup C, electrophoretic type (ET) 15 outbreak. No outbreak cases had occurred in the community at the time of the study, Methods, Total serogroup C capsular polysaccharide antibody (CPA) and function al bactericidal antibody (BA) responses were measured by enzyme-linked immunosorbent assay and bactericidal assay, respectively, Results. Ne isseria meningitidis mas recovered from the oropharynx of 13 (5.2%) of 249 aboriginal children including 4 (1.6%) serogroup C isolates, all with the designation C:2a:P1.2,5 ET15, Paired sera from 152 children w ere available for assay, For CPA the geometric mean concentrations and proportions with greater than or equal to 2 mu g/ml before and after immunization were 0.69, 18% and 12.3, 96%, respectively. A significant increase in serum CPA was achieved by children of all ages, with the greatest response occurring after age 11 years. Among infants <1year o ld 89% achieved concentrations of greater than or equal to 2 mu g/ml. For BA the pre- and post-vaccine geometric mean titers were 1.02 and 4 5.9, The response was significantly associated with age. BA titers gre ater than or equal to 1:8 mere present, before and after immunization, respectively, in 0 and 0% of infants <1 year old, 0 and 20% of 1- to 1.4-year-olds, 0 and 50% of 1.5- to 1.9-year-olds and 1 and 100% of gr eater than or equal to 2-year-olds. Conclusion. The age-related total and functional group C meningococcal antibody response after quadrival ent polysaccharide vaccine among aboriginals is similar to that report ed for Caucasian children. After age 2 all children made excellent CPA and BA responses. In the younger age groups the BA response was blunt ed but 82 to 95% achieved CPA titers of greater than or equal to 2 mu g/ml.