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目的 观察不同剂量的甲型肝炎 (甲肝 )减毒活疫苗免疫原性与免疫持久性。方法 对河北省正定县 4个村 16 6名 6～ 8岁事先经血清检测抗 HAV阴性的易感儿童 ,按村分成 4组 ,分别给予 0 .5、1、2及 2剂经 6 0℃ 3h灭活处理的甲肝减毒活疫苗 (滴度为 10 6.52 TCID50 )。并于接种后 3、12、2 4、36及 48个月采集观察对象血清 ,采用Abbott IMxmEIA试剂检测血清抗 HAV。并对接种 1剂、2剂活疫苗组免后 4年部分血清检测中和抗体。结果 免后 3个月抗体阳转率、抗体几何平均滴度(GMT)同疫苗滴度呈剂量效应关系。免疫后各组抗体水平于免疫后 3个月达高峰后逐年下降 ,12个月内下降较明显 ,12个月后下降缓慢。免疫后 4年接种 2剂活疫苗组抗体阳性率与GMT均高于接种 0 .5剂及 1剂组。接种 1、2剂活疫苗组部分经Abbott IMxmEIA试剂检测抗 HAV阴性的血清检测中和抗体 ,其阳性率为 6 0 %及 83%。结论 甲型肝炎减毒活疫苗的免疫原性与免疫持久性同疫苗的滴度有关 ,滴度为 10 6.83 TCID50 的减毒活疫苗具有较理想的免疫原性及免疫持久性。减毒活疫苗接种后近期内不必予以加强免疫
Objective To observe the immunogenicity and immune persistence of live attenuated hepatitis A (A) attenuated vaccine at different doses. Methods Sixteen children aged 6-8 years old in 4 villages of Zhengding County, Hebei Province, who were previously tested for serum anti-HAV negative susceptible children, were divided into 4 groups according to the village, and were given 0.5, 1, 2 and 2 doses respectively at 60 ℃ 3h inactivated live attenuated hepatitis A vaccine (10 6.52 TCID50). Sera were collected at 3, 12, 24, 36 and 48 months after inoculation, and serum anti-HAV was detected by Abbott IMxmEIA reagent. And inoculation of 1, 2 live vaccine group after 4 years of partial serum detection of neutralizing antibodies. Results The rate of antibody positive conversion and the geometric mean antibody titer (GMT) were in dose-dependent relationship with the vaccine titer after 3 months. After immunization, the level of antibody in each group dropped year by year after reached the peak 3 months after immunization, decreased more obviously within 12 months and then decreased slowly after 12 months. The positive rate and the GMT of antibody of two live vaccinated groups vaccinated 4 years after immunization were higher than those of 0.5 and 1 dose group. Neutralizing antibodies were detected in 1 and 2 doses of live vaccine against neutralizing antibodies against HAV detected by Abbott IMxmEIA reagent. The positive rates were 60% and 83% respectively. Conclusion The immunogenicity and immunocompetence of the live attenuated hepatitis A vaccine are related to the titer of the vaccine. The live attenuated vaccine with a titer of 10 6.83 TCID50 has good immunogenicity and immunocompetence. Live attenuated vaccines need not be boosted in the near future