目的　观察在甲型肝炎 (甲肝 )高发县、区用甲肝减毒活疫苗 (H2 株 )大面积接种后长期的流行病学保护效果。方法　选择浙江省嵊泗县和椒江区二个试点。二组小学生定群研究 ,观察 4年。试点内 1～ 15岁儿童普遍接种甲肝活疫苗。部分研究对象作血清中和试验、免疫回忆反应及免后 10年抗体检测。结果　接种组与未接种组甲肝发病率差别具有显著性 (P <0 .0 1) ,疫苗保护率为10 0 %。疫苗接种率与甲肝发病率二者具有明显负相关。全人口甲肝发病率分别下降了 94.5 %和90 .3% ,1～ 15岁儿童组发病专率分别下降了 96 .9%和 97.9% ,10年期间没有发生甲肝流行。血清学检测结果 :免后阴性血清 ,用体外中和法验证有 6 3.8%仍有中和作用 ,加强免疫 1针后回忆反应明显。免后 10年抗 HAV IgG的阳性率为 80 .2 %。结论　甲肝减毒活疫苗 (H2 株 )长期的流行病学效果明显。通过普遍接种甲肝活疫苗 ,第一次在甲肝高发地区和高发年龄组消除了甲肝的发生与流行 Objective To observe the long-term epidemiological protective effect of large-area hepatitis A attenuated live vaccine (H2 strain) in Hepatitis A (HF) counties. Methods Two pilots in Shengsi County and Jiaojiang District of Zhejiang Province were selected. Two primary school students group study, observed for 4 years. Hepatitis A live vaccine is generally given to children aged 1-15 years. Some of the subjects for serum neutralization test, immune recall reaction and 10 years after antibody test. Results The incidence of hepatitis A in vaccinated and non-vaccinated groups was significantly different (P0.01). The vaccine protection rate was 100%. Vaccination rate and incidence of hepatitis A have a clear negative correlation between the two. The prevalence of hepatitis A in the whole population decreased by 94.5% and 90.3% respectively, while the incidence rates of children aged 1-15 years decreased by 96.9% and 97.9% respectively. No hepatitis A epidemic occurred during the 10-year period. Serological test results: negative serum after free, in vitro neutralization method to verify that there is still 6 3.8% neutralization, strengthen the immune response after a needle reaction was obvious. The positive rate of anti-HAV IgG after 10 years was 80.2%. Conclusion The long-term epidemiological effect of attenuated live attenuated hepatitis A vaccine (H2 strain) is obvious. Through the universal vaccination of live Hepatitis A vaccine, the first time in the high incidence of hepatitis A and high incidence of age group to eliminate the occurrence and prevalence of hepatitis A