X Wang1, J Ma, Y Zhang. 1. Department of Epidemiology, Medical Centre of Fudan University, Shanghai 200032, China.
Abstract
OBJECTIVE: This study was carried out to assess the long-term persistence of antibodies against hepatitis A in different vaccine dosage groups. METHODS: One hundred and sixty-six susceptibles aged form 6 to 8 years old were selected in Zhengding county, and were divided into 4 different dose groups. Each group received 10(6.17)TCID(50), 10(6.52)TCID(50), 10(6.83)TCID(50) of attenuated hepatitis A vaccine or 10(6.83)TCID(50) of the same vaccine but treated with 60 degrees C for 3 hours. All subjects were bled at month 3, 12, 24, 36 and 48. All serum specimens were tested for antibodies to HAV using Abbott-IMx mEIA reagent. Part of the tested negative serum specimens were retested by neutralization assay for 10(6.52)TCID(50) and 10(6.83)TCID(50) dosage groups at 4 years after vaccination. RESULTS: The seroconversion rate and GMT 3 months after vaccination in each dosage group showed a significant dose-response relationship. Antibody levels reached the peak at month 3 in each group but declined dramatically within one year and the decline slowed down thereafter. The serocoversion rate and GMT in 10(6.83)TCID(50) dose group 4 years after vaccination was significant higher than those of other dosage groups. Positive rates of neutralizing antibodies in B and C dosage group were 60.0% and 83.3% respectively. CONCLUSION: The immunogenicity and long-term persistence were related to the attenuated hepatitis A vaccine titer. The vaccine, whose titer was 10(6.83)TCID(50), had good immunogenicity and long-term persistence. Booster dose was not needed within short time after initial vaccination.
OBJECTIVE: This study was carried out to assess the long-term persistence of antibodies against hepatitis A in different vaccine dosage groups. METHODS: One hundred and sixty-six susceptibles aged form 6 to 8 years old were selected in Zhengding county, and were divided into 4 different dose groups. Each group received 10(6.17)TCID(50), 10(6.52)TCID(50), 10(6.83)TCID(50) of attenuated hepatitis A vaccine or 10(6.83)TCID(50) of the same vaccine but treated with 60 degrees C for 3 hours. All subjects were bled at month 3, 12, 24, 36 and 48. All serum specimens were tested for antibodies to HAV using Abbott-IMx mEIA reagent. Part of the tested negative serum specimens were retested by neutralization assay for 10(6.52)TCID(50) and 10(6.83)TCID(50) dosage groups at 4 years after vaccination. RESULTS: The seroconversion rate and GMT 3 months after vaccination in each dosage group showed a significant dose-response relationship. Antibody levels reached the peak at month 3 in each group but declined dramatically within one year and the decline slowed down thereafter. The serocoversion rate and GMT in 10(6.83)TCID(50) dose group 4 years after vaccination was significant higher than those of other dosage groups. Positive rates of neutralizing antibodies in B and C dosage group were 60.0% and 83.3% respectively. CONCLUSION: The immunogenicity and long-term persistence were related to the attenuated hepatitis A vaccine titer. The vaccine, whose titer was 10(6.83)TCID(50), had good immunogenicity and long-term persistence. Booster dose was not needed within short time after initial vaccination.