流行性乙型脑炎减毒活疫苗大面积接种后安全性和流行病学效果的5年观察

目的　考核乙脑减毒活疫苗大面积接种后的安全性和降低乙脑发病率,在乙脑高发区安徽省蒙城和涡阳县进行为期５ 年（１９９２ ～１９９６ 年） 的人群观察。方法　观察对象为１ ～６ 岁儿童。１ 岁初免１ 针,２ 岁加强１ 针。结果　通过５ 年连续观察共接种乙脑活疫苗３３５ ９４１ 人。表明：①疫苗对小龄儿童接种后近期和５ 年内均未出现不良反应,表明疫苗是安全的。②当地乙脑平均总发病率有显著性下降,从接种观察前１９８７ ～１９９１ 年的１１ ．３４／１０ 万下降到１９９２ ～１９９６ 年的２ ．７４／１０ 万（ Ｐ＜ ０ ．００５） 。③１ ～６ 岁儿童发病专率观察前５ 年涡阳县平均为５６ ．２４／１０ 万,蒙城县为４４ ．５７／１０ 万;普种后５ 年,两县分别下降至１３ ．８３／１０ 万和１６ ．９４／１０ 万（ Ｐ＜ ０ ．００５） 。④有接种史儿童发病率明显低于无接种史的儿童（２ ．２１／１０ 万和３５８ ．１／１０ 万） 。１８ 例死亡病例全部为无接种史者。⑤疫苗免疫一针后中和抗体阳转率为８３ ．８７ ％ ～９４ ．７４ ％ 。结论　乙脑活疫苗安全有效,接种后可明显提高机体的免疫力,对降低乙脑发病控制流行效果显著。

A large-scale study on the safety and epidemiological efficacy of Japanese encephalitis (JE) live vaccine (SA14-14-2) in the JE endemic areas

Objective To measure the safety and epidemiological efficacy of Japanese encephalitis live vaccine(SA14-14-2).Methods Guoyang and Mengcheng counties in Anhui Province,were chosen as observed spots where high incidence of JE was noticed in China. 1-6 years old children in two counties were inoculated with vaccine manufactured by Chengdu Biological Products Institute in the beginning of 1992. All children of 1-6 years old received one primary dose of live vaccine and the children at one or two years old were respectively given one dose for primary or booster vaccination in 1993-1996. Side effects of live vaccine had been under surveillance for five years for its safety JE cases during the epidemic season (Jun to October),were diagnosed clinically and serologically. Results Data on the safety and efficacy of the JE live vaccine(SA14-14-2) are listed as follows:1) During 1992-1996, a total number of 335 941 children at 1-6 year old were vaccinated. No vaccine-associated encephalitis,meningitis or other serious adverse events were observed. 2) The incidence of JE case has greatly declined since the beginning of large-scale vaccination. The average JE morbidity decreased from 11.34 / 100 000 in 1987-1991 to 2.74 / 100 000 in 1992-1996( P < 0.005 ). 3) The incidence of JE case in 1-6 years old in thatperiodreduced as well. Theaverage JEmorbiditydecreased from 56.24/100 000 to 13.83/100 000 in Guoyang and from 44.57/100 000 to 16.94/100 000 in Mengcheng counties respectively( P <0.005). Most of the JE cases (94%) occurred in the unvaccinated children including all the 18 death cases. 4) Serum antibody response to immunization were measured by plaque reduction neutralization test. Neutralizing antibody seroconversion after one single vaccination were 83.87%-94.74%. Conclusion The results further confirmed that JE live vaccine is safe for children and effective for prevention from JE disease in JE endemic areas.