Adverse Reaction and Immunogenicity Induced by Freeze-dried Live Attenuated Hepatitis A Vaccine

Objective To observe the adverse reaction and immunogenicity induced by freeze-dried live attenuated hepatitis A(HA)vaccine.Methods A random and open clinical trial was performed in children at more than 18 months of age,who were uninoculated with HA vaccine,and adults at 18～35 years of age in Yancheng City,Jiangsu Province,China.All the subjects were inoculated with a single dose of freeze-dried live attenuated HA vaccine and observed for immediate reactions within 30 min as well as local and systemic reactions 24,48 and 72 h after inoculation.The serum samples were collected 30 d after inoculation for evaluation of immunogenicity.Results No local reactions were observed in all the 562 subjects,while mild fever in 35 subjects(6.23%).Of the 471 subjects observed for immunogenicity of vaccine,the positive rates of anti-HAV and protective antibody were 99.8%and 96.4%respectively,and the GMC of anti-HAV was 527.4 mIU/ml,which increased by 30.3 folds compared with that before immunization.The positive rate of protective antibodies in children and adults after immunization were 97.0%and 95.9%,while the GMCs of anti-HAV were 84.1 and 2 119.1 mIU/ml,respectively,which showed significant difference with those before immunization.The positive rates of anti-HAV and protective antibody and GMCs of anti-HAV of 277 susceptible subjects after immunization were 99.6%, 93.9%and 92.6 mIU/ml respectively.However,the antibody positive rate of susceptible children after immunization was significantly higher,while the GMC of anti-HAV was significantly lower than that of susceptible adults.Conclusion Domestic freeze-dried live attenuated HA vaccine induced mild adverse reaction but good immunogenicity,which was worthy of popularization.