建立群体免疫屏障控制甲型肝炎流行的效果研究

目的 大面积接种甲型肝炎(甲肝)疫苗，建立群体免疫屏障，控制甲肝周期性流行效果评价。方法 对甲肝易感人群进行逐步免疫覆盖，并选择不同流行强度地区的人群进行抗—HAV IgG监测，分析评价甲肝疫苗累计接种率与人群免疫水平、甲肝发病率之间的相关性。结果 ①1993—2000年8年间累计接种甲肝疫苗1981805人份，累计接种率为34．15％，学龄前儿童、中小学生、15—45岁年龄组人群累计接种率分别为84．46％、82．23％、15．14％。2000年甲肝发病率仅为8．26／10万。②1998年人群抗—HAV IgG阳性率为74．24％，至2000年抗—HAV IgG阳性率达83．68％，其中2—4、6—8、13—15、20一、30—39岁年龄组的抗—HAV IgG阳性率已分别达到74．02％、68．49％、79．41％、85．71％、90．80％。③相关与回归分析，人群甲肝疫苗累计接种率与甲肝抗体阳性率存在正相关关系，r全市＝0．91，F=15．10，P＜0．03。结论 大面积接种甲肝疫苗后，人群甲肝抗体阳性率达到85％左右，有效地构筑了甲肝的群体免疫屏障，阻断了甲肝后续的周期性流行，甲肝发病率控制在历史最低水平。

Study on the effects of controlling hepatitis A epidemics by building the colony immune defence

Objective To build the colony immune defence and to control the periodic epidemics of hepatitis A after a mass vaccination of live attenuated hepatitis A vaccine. Methods Through yearly observing the correlation of the accumulative inoculation rates of live attenuated hepatitis A vaccine, the crowd immune standard and the morbidity of hepatitis A after administered live attenuated hepatitis A vaccine among susceptible population and surveilling anti-HAV IgG in the different epidemic areas. Results (1)The accumulative inoculation rates of live attenuated hepatitis A vaccine was 34.15 % in 8 years from 1993 to 2000, among which they were 84.46 %, 82.23 % and 15.14 % in the preschool children, primary and middle school student and 15-45 age groups respectively. The morbidity of hepatitis A decreased to 8.26/ 100 000 in 2000. (2)The crowd positive rates of anti-HAV IgG were 74.24 % in 1998 and 83.68 % by 2000. Among which they were 74.02 %, 68.49 %, 79.41 %, 85.71 % and 90.80 % in 2- 4, 6- 8, 13-15 , 20- and 30-39 age groups respectively. (3)The accumulative inoculation rates were 37.36 %, 51.08 % and 28.68 % in the inspection areas of Tongtai, Binhai and Yandu respectively. The crowd positive rates of anti- HAV IgG in three inspect area were 85.71 %, 85.94 % and 78.63 % respectively. It was noticed the correlation between the accumulative inoculation rates and the crowd positive rates of anti- HAV IgG was ( r city = 0.91 , F = 15.10 , P < 0.03 ). Conclusion The results showed that the crowd positive rates of anti-HAV IgG had increased to 85% while, the colony immune defence of hepatitis A was effectively built to break the periodic epidemics of hepatitis A. The morbidity of hepatitis A decreased to the lowest level in the history.