宁波市实施乙型肝炎疫苗计划免疫后儿童乙型肝炎病毒血清流行病学研究

目的了解宁波市实施乙型肝炎疫苗(乙肝疫苗)计划免疫7年后,儿童乙型肝炎病毒(HBV)感染及免疫状况.方法采用整群分层抽样法调查1982～1995年出生儿童血清HBsAg和抗-HBs阳性率(RIA法).结果①1992～1995年出生的免疫人群HBsAg阳性率为2.66%,比未免疫人群(10.95%)下降了75.71%(χ2=22.91,P＜0.0001);②免疫人群抗-HBs阳性率达65.95%,显著高于未免疫人群的41.03%(χ2=113.67,P＜0.0001);③在计划免疫后的第5～7年起显现了免疫人群HBsAg阳性率升高和抗-HBs阳性率下降的迹象.结论宁波市实施乙肝疫苗计划免疫7年后,儿童对HBV已呈现出高免疫、低感染的特征;但需进一步研究计划免疫4～5年后,免疫人群HBsAg阳性率升高、抗-HBs阳性率下降的现象和乙肝疫苗加强免疫的适时问题.

Seroepidemiological analysis of characteristic of hepatitis B virus in children after vaccination in Ningbo

OBJECTIVE: To understand the immunity of children in Ningbo after hepatitis B vaccination for seven years and to explore the best time for booster. METHODS: One thousand nine hundred and twenty serum samples from children born in 1982 - 1995 were tested for anti-HBs and HBsAg, using RIA. RESULTS: (1) HBsAg positive rate (2.66%) was lower in vaccinated children born in 1992 - 1995 than those unvaccinated (10.92%) born in 1982 - 1995. HBsAg positive rate had a drop of 75.71% (chi(2) = 22.91, P < 0.0001). (2) Anti-HBs positive rates (65.95%) in vaccinated children was much higher than that in unvaccinated children (41.03%) (chi(2) = 113.67, P < 0.0001). (3) It also showed that children's positive rate of HBsAg increased and anti-HBs dropped after 5 - 7 years of vaccination. CONCLUSION: After immunization of hepatitis B vaccine for 7 years, high immunity and low infection rate of HB in children it appeared in Ningbo. However it is necessary to further study the reason causing the increase of HBsAg positive rate and/or deerease of anti-HBs positive rate, and the suitable time frame of boostering, after 4 or 5 years of primary vaccination.