Persistence of Protective Antibody Titers 12-24 Months After NmVac4-A/C/Y/W-135-DT Vaccination: Follow Up Study

The purpose of this study is to collect serum samples to evaluate duration of protection for NmVac4-A/C/Y/W-135-DT, based on titers determined by Serum Bactericidal Assay with human complement (hSBA). This assay is used to evaluate immunogenicity of meningococcal vaccines, as a surrogate for efficacy. A titer ≥ 1:8 is considered protective.

Objectives are to evaluate duration of protective antibody titer for NmVac4-A/C/Y/W-135-DT for all four serogroups, and determine if subjects with lower titers, but ≥:8 retain protective levels of antibody at 12-24 months.

Participants in trial # JN-NM-002, who seroconverted for serogroups A and C will be contacted and asked to provide a blood sample at 12-24 months after vaccination with NmVac4-A/C/Y/W-135-DT™.

Serum Bactericidal Assays will be performed to evaluated persistence of protective antibody titer for NmVac4-A/C/Y/W-135-DT for all four serogroups, to determine if subjects who seroconverted with lower titers retain protective levels of antibody (titer ≥:8) at 12-24 months after vaccination.

Inclusion criteria

• Willing and able to give informed consent
• Participant in trial JN-NM-002
• Seroconverted in trial JN-NM-002 for both serogroups A and C

Exclusion criteria

• Chronic medication use or medical history that, in the opinion of the Investigator, may impact the quality of the sample or safety of the subject