OBJECTIVETo evaluate the safety of meningococcal group AC bivalent polysaccharide conjugate vaccine among children aged 5-24 months old.

METHODSFrom July 2011 to June 2012, a total of 34 411 children aged 5-24 month-old who voluntarily vaccinated meningococcal group AC bivalent polysaccharide conjugate vaccine in Zhongshan city were included. The adverse effects within 72 hours were recorded and analyzed.

RESULTS34 411 children were recruited, including 18 708 boys (54.36%), whose mean age were ( 11.4 ± 3.9 ) months old.Within 72 hours, the incidence rates of local adverse effects were 0.76% (261/34 411) for erythema,0.57% (197/34 411) for sclerosis,0.56% (191/34 411) for swelling,0.42% (143/34 411) for pain,0.15% (53/34 411) for pruritus, and 0.15% (50/34 411) for rash on the injection site. The overall incidence rate of local adverse effects was 1.61% (554/34 411; 95%CI:1.48%-1.74%). The incidence rates of systemic adverse effects were 0.98% (312/34 411) for fever,0.48% (164/34 411) for anorexia,0.31% (108/34 411) for diarrhea,0.29% (100/34 411) for malaise,0.20% (70/34 411) for nausea and vomiting, and 0.08% (26/34 411) for headache. The overall incidence rate of systemic adverse effects was 1.64% (565/34 411; 95%CI:1.51%-1.78%).25 children (0.07%) had hyperpyrexia ( > 39°C), and the time of duration lasted less than 48 hours.16 children (0.05%) had symptoms of cold, such as cough and catarrh.No accident and other serious events were reported. The incidence rate of systemic adverse effects among boys was 1.79% (334/18 708), which was higher than that of girls (1.47%, 231/15 703), the difference showed statistical significance (χ(2) = 5.22, P < 0.01). The incidence rate of systemic adverse effects among children aged 5-12 month-old was 1.78% (411/23 113), which was higher than that among children aged 13-24 month-old (1.36%, 154/11 298), the difference showed statistical significance (χ(2) = 8.10, P < 0.01). The incidence rate of local adverse effects in children vaccinated the first dose was 1.72% (536/31 129), which was higher than that in children vaccinated the second or third dose (0.55%, 18/3282), the difference showed statistical significance (χ(2) = 25.81, P < 0.01). The incidence rate of systemic adverse effects in children vaccinated the first dose was 1.73% (539/31 129), which was higher than that in children vaccinated the second or third dose (0.79%, 26/5282), whose difference also showed statistical significance (χ(2) = 16.22, P < 0.01).

CONCLUSIONThe safety of meningococcal group AC bivalent polysaccharide conjugate vaccine among children aged 5-24 months old is relative good.