Comparative immunogenicity of three meningococcal vaccines as the first booster dose in children primed with MPCV-AC in China.

This study aimed to compare the immunogenicity of three meningococcal vaccines used as booster doses in children primed with MPCV-AC in China. A total of 250 eligible children were enrolled to receive MPSV-AC, MPCV-ACYW135, or MPCV-AC as a booster dose. Participants were subdivided into day 7 and day 28 subgroups based on the timing of sample collection. Blood samples were collected at baseline, day 7, and day 28 to measure IgG antibodies against serogroups A and C by ELISA. Baseline GMCs of IgG were 4.34 μg/mL (seropositivity: 79.2%) for serogroup A and 4.36 μg/mL (seropositivity: 82.0%) for serogroup C, both negatively correlated with age and time interval (p < 0.05). All vaccines significantly increased IgG levels at days 7 and 28 post-booster compared with baseline (p < 0.01). In the day 7 group, MPSV-AC yielded a lower GMC (19.14 μg/mL) and seroconversion rate (43.8%) for serogroup A compared with MPCV-ACYW135 (44.69 μg/mL, 78.9%) and MPCV-AC (43.06 μg/mL, 78.1%). In the day 28 group, MPSV-AC showed a comparable GMC for serogroup A (44.42 μg/mL vs. 60.39 μg/mL and 44.66 μg/mL) and a higher GMC for serogroup C (113.40 μg/mL) than MPCV-ACYW135 (59.62 μg/mL) and MPCV-AC (72.75 μg/mL). Only two mild adverse events were reported during the study period. These findings suggest that boosting with MPSV-AC, MPCV-ACYW135, or MPCV-AC is safe and immunogenic; however, further studies are warranted to assess the long-term persistence of immunity conferred by these booster vaccines.