Safety and immunogenicity of groups A+C meningococcal conjugate vaccine.

Objective To observe the safety and immunogenicity of freeze-dried groups A + C meningococcal conjugate vaccine. Methods A double-blind, randomized and parallel controlled clinical trial was carried out in the children at ages of 6 ～ 9 months and not less than 3 years. The children in trial groups were immunized with freeze-dried groups A + C meningococcal conjugate vaccine. However, in control groups, the children at ages of 6 ～ 9 months were immunized with group A meningococcal polysaccharide vaccine, while those at ages of not less than 3 years with groups A + C meningococcal polysaccharide vaccine. The adverse reaction, serum antibody content and antibody positive conversion rate after immunization were observed. Results The systemic adverse reaction rates in the children at ages of 6 ～ 9 months in trial and control groups were 1. 67% and 4. 58%, while those of local adverse reaction rates were 0. 83% and 2. 08%, respectively. However, the systemic adverse reaction rates in the children at ages of not less than 3 years in trial and control groups were 2. 50% and 3. 33% respectively, while those of local adverse reaction rates were both 0. 83%. The contents of antibody against group A meningococcus in sera of children at ages of 6 ～ 9 months in trial and control groups were 22. 27 and 3. 61 μg / ml, while the antibody positive conversion rates were 99. 01% and 66. 67%, respectively, which showed significant difference(P 0. 05). The contents of antibodies against groups A and C menigococcus in sera of children at ages of not less than 3 years in trial group were 21. 28 and 17. 94 μg / ml, while the antibody positive conversion rates were 99. 04% and 98. 08%, respectively. However, in the sera of children at ages of not less than 3 years in control group, the contents of antibodies against groups A and C menigococcus were 34. 43 and 22. 66 μg / ml respectively, while the antibody positive conversion rates were both 98. 04%. The antibody contents of children at ages of not less than 3 years in trial and control groups showed significant difference(P 0. 05), while the antibody positive conversion rates showed no significant difference(P 0. 05). Conclusion Freeze-dried groups A + C meningococcal conjugate vaccine showed high safety and immunogenicity in the children at ages of 6 ～ 9 months and not less than 3 years.