[A seroepidemiologic analysis of hepatitis B in Sichuan province].

OBJECTIVE: To understand the changes of hepatitis B infection rates, before and after the hepatitis B vaccine was included into EPI, and to evaluate the effect of immunization which would lead to the development of a more appropriate hepatitis B control strategy. METHODS: Seroepidemiologic method, with multi-section random sampling method were chosen. 14 sites from 8 counties were involved. 2-4 ml of the vein blood was drawn from all the individuals engaged in the study including 3806 samples. HBsAg, anti-HBs, anti-HBc of the samples were tested with ELISA. RESULTS: Standardized positive rates of HBsAg and HBsAb were found as 7.05% and 29.77% respectively with the overall infection rate of HBV as 40.30%. The hepatitis B vaccine coverage of the children under 15 years was 70.73% and the positive rates for both HBsAg and anti-HBs were 2.62% and 56.68%, respectively. The coverage of hepatitis B vaccine among children under 3 years was 83.44% and the positive rates of both HBsAg and anti-HBs were 1.47% and 67.69% respectively, hepatitis B vaccine coverage of children under 3 years was 85.77%, with positive rates of HBsAg and anti-HBs as 1.78% and 75.44% respectively. CONCLUSION: Results from our study revealed that since the introduction of hepatitis B vaccination, the prevalence rates of HBsAg and HBV infection had an obvious decline, especially in children aged under 15 years of old, suggesting that some changes had occurred in the epidemic characteristics of hepatitis B in Sichuan.

[The immunogenicity and safety of 10 microg recombination yeast hepatitis B vaccine applied in expanded population].

OBJECTIVE: To assess the feasibility of the 10 microg recombination yeast hepatitis B vaccine in the expanded applicable population group aged 5 - 18. METHODS: People with both HBsAg and anti-HBs negative were selected to take two-stage clinical experiment and the safety and immunogenicity were observed. Safety observation was conducted in 925 subjects, while 568 for immunogenicity. The observation group (aged 5 - 18) included 493 subjects, and (age > 18) 75 enrolled in control group. For the observation group, there were three sub-groups including a child group (141, aged 5 - 6), early youth group (177, aged 12 - 13), and youth group (175, aged 16 - 18). Both groups were administered with 10 microg recombination yeast hepatitis B vaccines with 3 doses at 0 month, 1st month, 6th month. To assess the immunogenicity, the vaccination reactions were observed during the following 4 weeks in order to assess the vaccine safety. The blood samples were taken during 4 - 6 weeks after fully vaccinated, and then anti-HBs were tested with RIA and analyzed by comparing the positive rate of anti-HBs, the geometric mean titer (GMT) and the protective rate between the two groups. RESULTS: Both observation and control group didn't show any general reactions, adverse events following immunization (AEFI) or coincidental cases when observed at 0.5 h, 6 h, 24 h, 48 h, 72 h, 1 week, 2 weeks, 3 weeks, 4 weeks after being vaccinated. The result of serum test showed, the positive rates of child group, early youth group, youth group and control group were respectively 100.00% (141/141), 97.18% (172/177), 98.29% (172/175) and 89.33% (67/75); the GMTs of anti-HBs were respectively 440.28, 875.38, 467.80, 131.06 U/L; the protective rates were respectively 100.00% (141/141), 97.18% (172/177), 97.14% (170/175) and 86.67% (65/75). The positive rate, GMT and protective rate of the experimental group were all higher than that of control group (chi(2)(positive rate) = 12.77, 5.12, 7.99; t(GMT) = 3.89, 4.13, 5.91; chi(2)(protective rate) = 16.81, 8.60, 8.44; P < 0.05). CONCLUSION: This vaccine could be expanded to 5 - 18 year-old population with safety and effectiveness, the positive rate and protective rate of anti-HBs were both higher than that of control group.