Figure 3. Meningococcal Serogroup C Polysaccharide Specific Immunoglobulin G (IgG) Avidity Indices (AI).

Avidity indices divided in low, intermediate and high (a) and mean avidity indices (b) per age group prior to (T0) and 1 month (T1) and 1 year (T2) after the MenC conjugate booster. Only serum samples from participants with an IgG concentration of ≥0.25 µg/ml at T0 were included in the analyses (44 10-year-olds, 49 12-year-olds and 60 15-year-olds). Serum samples were diluted to a concentration of 25 ng/ml. Avidity index  =  (amount of IgG still bound after treatment with 0.5 M NH₄SCN/amount of IgG with PBS) x 100.