OBJECTIVEIn order to evaluate the safety and immunogenicity of group A + C meningococcal polysaccharide vaccine, a controlled field trial was performed among children at 6-24 months and 5-13 years old in Longsheng county, Guangxi Zhuang Autonomous Region.

METHODSMore than 600 children were selected in this trial. 428 children, aged 6-24 month-old and 5-13 year-old were involved in two experimental groups and were inoculated 100 microg of group A + C meningococcal polysaccharide vaccine. 103 children in positive control group were inoculated 50 microg of group A meningococcal polysaccharide vaccine while 94 children in negative control group were inoculated 30 microg of Typhoid Vi polysaccharide vaccine. Both systemic and local reactions were observed in each group at 6 h,24 h,48 h and 72 h after inoculation. Blood samples were collected in all children before and at 1 month after inoculation. Additionally, at least 50 blood samples were taken in each experimental group at 6 and 12 months after inoculation. Serum bactericidal antibody was tested by micro bactericidal test.

RESULTSBoth systemic and local reactions were mild in two experimental groups with only 3 children (0.7%) had > or = 37. 6 degrees C fever, 4 children (0.9%) appeared mild areola but all adverse reaction disappeared within 48 hours. In 5-13 year-old experimental group, the rates for four-fold increase of bactericidal antibody were 96.59% and 92.15% to group A and group C meningococcus respectively at 1 month after inoculation, and remained 90.91% and 90.08% at 12 months after inoculation.

CONCLUSIONGroup A + C meningococal polysaccharide vaccine was safe and having good immunogenicity among Chinese children.