Studies on Safety and Sero-effect of Freeze-dried Live Attenuated Hepatitis A Vaccine

This study was to assess the safety and sero-effect of freeze-dried live attenuated hepatitis A vaccine(H 2 strain)inoculated to humans In a primary school of Ningbo,179 students aged 9 to 10 years inoculated with this vaccine were observed for local and systemic responses after 30 min,8,24,48,72 h The body temperature and other clinical responses were recorded every two days. 68 students with negative anti-HAV-IgG,normal SGPT,without history of liver diseases and none of hepatic symptoms were inoculated with this vaccine and 2 months later the finger blood was taken to detect anti-HAV antibody level. 28 students who definitely were injected HA vaccine(liquid)within 5 years but with low antibody level(1∶2,ELISA)were boosted with this vaccine again The method used to test antibody is EIA competitive inhibition test,marked by WHO standard sample(100mIU/ml) In whole period of observation,all students had no abnormal clinical response The freeze-dried live attenuated hepatitis A vaccine was highly safe as same as the liquid one The positive seroconversion rate of anti-HAV-IgG two months later was 91 2%,the geometric mean titer(GMT)level of anti-HAV-IgG was 227 6mIU/ml The GMT level in boosted group rose much more higher than that in single injection group,that was about 1?223 6mIU/ml:227 6mIU/ml,indicating a significant difference between the two groups(P0 01) Freeze-dried live attenuated hepatitis A vaccine(H 2 strain)is of high safety,high seroconversion rate and high GMT level