ABSTRACT
Objective: Evaluation of tolerability, safety and immunogenicity ofa two-dose series of a quadrivalent meningococcalpolysaccharide diptheria toxoid conjugate (ACYW-D) vaccine inIndian and Russian infants/toddlers.Design: Open-label, single-arm, phase III multi-national trial.Study participants: 300 children aged 9-17 months, previouslyunvaccinated against meningococcal disease from four siteseach in India (n=200) and the Russian Federation (n=100).Intervention: Two 0.5 mL doses of ACYW-D by intramuscularinjection, 3-6 months apart.Main outcome measures: Meningococcal antibody titers toserogroups A, C, W-135 and Y, determined using a serumbactericidal assay in the presence of human complement beforevaccination and 28 days after the second vaccination. Titers ?1:8against either/all of the A, C, W-135 or Y were considered sero-protective.Results: After dose 2, 95.7–99.5% and 92.9–99.0% of infants/toddlers achieved seroprotection across the four serogroups inIndia and the Russian Federation, respectively. No immediateadverse events were reported after any dose of ACYW-D.Solicited reactions were reported in 49.2% of participants, andwere mainly of Grade 1 severity, and resolved within three days.Unsolicited adverse events were reported in 19.1% of infants:one event (Grade 3 diarrhea, resolving within one day) wasconsidered related to study vaccine. No non-serious adverseevents led to premature withdrawal from the study. Four seriousadverse events were reported; none were considered related tostudy vaccine. No deaths occurred during the study.Conclusions: A two-dose series of ACYW-D vaccine in Indianand Russian children (9-17 month) was well-tolerated with nosafety concerns, and induced robust bactericidal antibodyresponses against the meningococcal serogroups contained inthe vaccine