TOTAL AND FUNCTIONAL ANTIBODY-RESPONSE TO A QUADRIVALENT MENINGOCOCCAL POLYSACCHARIDE VACCINE AMONG CHILDREN

Objective: To determine total and functional serogroup C antibody resp onse after vaccination with a quadrivalent meningococcal polysaccharid e vaccine. Design: Prospective, before and after intervention study. S ubjects: Study subjects were between the ages of 0.5 and 19.9 years, a nd were eligible for a community-wide public health immunization campa ign against Neisseria meningitidis serogroup C. Methods: Total and fun ctional antibody response was measured by enzyme-linked immunosorbent assay and bactericidal assay, respectively. Results: One month after v accination, total capsular polysaccharide antibody significantly incre ased in all age groups; a significant rise in bactericidal antibody, t hat correlated with total capsular polysaccharide antibody, was seen i n 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 caps ular polysaccharide antibody concentration appears to be a useful surr ogate 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 con tinuing risk of disease. Because of the differences in the total and b actericidal antibodies formed, vaccine efficacy trials are required to define which serologic measures are associated with protection.