Cross-Sectional Study On Varicella Vaccine Efficacy In Children

[Objective] To observe the long term immune effects and its influence factors of 1 dose Varicella vaccine vaccination schedule in children and to explore the timing of strengthen immunization program. [Methods] 633 children aged from 12 months to 12 years old were recruited into the study in January-August 2008. Those children had been injected 1 dose Varicella vaccine either imported product or domestic product. They were divided into 8 groups based on the age. All children were collected finger tip blood and 629 blood samples were valid because of Varicella medical record tested in 4 blood samples. The level of Varicella IgG antibody was tested by ELISA method. Meanwhile, Varicella vaccine vaccination record and varicella disease history were also investigated in the study. [Results] Mean antibody positive rate was 69.0% and those of Shanghai native children were much higher than those of children from other provinces (90.1% vs. 84.6%, P=0.047). Children varicella antibody titers showed a skewed distribution (P-25=40.19, P-50=96.42, P-75= 290.82)mIU/ml, Antibody on the values for Logarithm were 2.021+/-0.691 (95%CI:1.967-2.075)IU/ml. Different years since vaccination and different age groups inoculated on the antibody titer was statistically significant, Respectively, F = 2.723, P = 0.006 and F = 3.933, P = 0.002. Antibody in 4 year age group was the lowest point compared to other groups.GMC of antibody of imported product was much higher than that of domestic product ( 72.1% vs, 64.0%, P = 0.034). [Conclusion] 4 years after Varicella vaccination, antibody titers in the body dropped to the lowest point, children were susceptible to Varicella. To strengthen the immune body, children should have another 1 dose of VarV four years after children vaccinated the first dose to get more effective immune protection.