[Observation of live, attenuated hepatitis A vaccines in humans]

Hepatitis A viruses L-A-1 and MBB strains were attenuated by serial passages in laboratory, then appropriately attenuated strains were screened based on marmosets experiments. Three live attenuated vaccine lots L-A-1/P14, L-A-1/P21, MBB/P13 (35 degrees C) were prepared respectively. Three vaccine lots titer were 10(5.5), 10(5.0), 10(4.5) TCID50/ml. Each vaccine lot was inoculated into 2 adults and 8 children 1.0 ml intramuscularly in the upper arm. All volunteers were closely observed for 4 weeks after the inoculation: No one showed local or systemic side-effects and serum ALT, ICD were normal. Every body developed anti-HAV 2-3 weeks postinoculation. Anti-HAV IgM also seroconverted. Neutralizing antibody was detected in serum 4-6 months after inoculation. Three vaccine lots showed no significant difference in safety and immunogenicity. The experimental data showed that the live vaccines were safe and had good immunogenicity.