Group A plus Group C Meningococcal Conjugate Vaccine (Wuhan Institute of Biological Products)

To evaluate the safety and immunogenicity of freeze-dried group AC meningococcal conjugate vaccine in infants aged 2 to 11 months. The primary objective was to evaluate the safety of freeze-dried group AC meningococcal conjugate vaccine in infants aged 2 to 11 months and the antibody seroconversion rate and 4-fold titer increase after vaccination with freeze-dried group AC meningococcal conjugate vaccine. The secondary objective was to evaluate the level of antibodies against group AC meningococcal capsular polysaccharides in the serum of infants aged 2 to 11 months before and after immunization.