[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 dcreased 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 that period reduced as well. The average JE morbidity decreased 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%.


CONCLUSIONS
The results further confirmed that JE live vaccine is safe for children and effective for prevention from JE disease in JE endemic areas.
Zhou
B
B
Chengdu Biological Products Institute.
Jia
L
L
Xu
X
X
D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004664:Encephalitis Virus, Japanese / Q000276:immunology*; D004672:Encephalitis, Japanese / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009017:Morbidity; D014611:Vaccination; D014613:Vaccines, Attenuated; D014765:Viral Vaccines
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines