RESUMO
<p><b>OBJECTIVE</b>To evaluate the safety of meningococcal group AC bivalent polysaccharide conjugate vaccine among children aged 5-24 months old.</p><p><b>METHODS</b>From 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.</p><p><b>RESULTS</b>34 411 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).</p><p><b>CONCLUSION</b>The safety of meningococcal group AC bivalent polysaccharide conjugate vaccine among children aged 5-24 months old is relative good.</p>