Total and functional antibody response to a quadrivalent meningococcal polysaccharide vaccine among children

Objective: To determine total and functional serogroup C antibody response after vaccination with a quadrivalent meningococcal polysaccharide vaccine. Design: Prospective, before and after intervention study. Subjects: Study subjects were between the ages of 0.5 and 19.9 years, and were eligible for a community-wide public health immunization campaign against Neisseria meningitidis serogroup C. Methods: Total and functional antibody response was measured by enzyme-linked immunosorbent assay and bactericidal assay, respectively. Results: One month after vaccination, total capsular polysaccharide antibody significantly increased in all age groups; a significant rise in bactericidal antibody, that correlated with total capsular polysaccharide antibody, was seen in children 18 months of age and older. At 1 year bactericidal antibody titers were maintained but capsular polysaccharide antibody declined substantially in children younger than 5 years. Conclusion: Total capsular polysaccharide antibody concentration appears to be a useful surrogate measure of bactericidal antibody in children 18 months and older. Children who originally received the vaccine at less than 18 months of age should be considered for revaccination if there is a new or continuing risk of disease. Because of the differences in the total and bactericidal antibodies formed, vaccine efficacy trials are required to define which serologic measures are associated with protection.