目的　调查HBV表面抗原(hepatitis B surface antigen，HBsAg)阳性母亲所生低体重儿HBV感染及血清学动态变化趋势，分析该类极特殊儿童HBV感染情况及免疫效果。方法　选取六安市24家医院或产科在2016—2021年出生的HBsAg阳性母亲所生低体重儿，分类统计姓名、性别、体质量、早产、及时接种乙型肝炎疫苗（hepatitis B vaccine，HepB）和接种剂数等，采用磁微粒化学发光法定量检测HBsAg和HBV表面抗体（hepatitis B surface antibody，HBsAb）浓度，分析比较抗体阳性率和抗体几何平均浓度（geometric mean concentration，GMC）。结果　研究共纳入172名低体重儿，其中121名完成了血样采集，平均年龄为（3.7±1.7）岁，体质量中位数为2.30 kg，早产儿占58.68%，HepB首针及时接种人数占75.21%，完成HepB基础免疫与加强免疫的对象分别有117、4人，HBV感染率为5.79%。在未感染对象中，加强免疫组与基础免疫组的HBsAb GMC差异有统计学意义，Z=-2.17，P=0.026；在未感染HBV且仅完成基础免疫的调查对象中，及时接种HepB、早产、出生体质量均不影响GMC。HBsAb阳性对象中，基础免疫组与加强免疫组相比，阳性率差异无统计学意义（χ²=2.45，P=0.118），但2组间GMC差异有统计学意义（Z=-2.25，P=0.024）。在仅完成基础免疫且未感染HBV的对象中，HBsAb阳性率和GMC随接种时间延长而总体呈下降趋势。结论　六安地区HBsAg 阳性母亲所生低体重儿的HBV感染率较高，HepB接种率较低，HBsAg和HBsAb总水平较低，需加强低体重儿的HepB 0-1-2-7月龄免疫程序的实施。

Objective　To investigate the trends in HBV infection and serological dynamics in low birth weight infants born to HBV surface antigen (HBsAg)-positive mothers, and to analyze HBV infection and the effectiveness of immunization in this very special group of children.Methods　Low birth weight infants born to HBsAg-positive mothers in 24 hospitals or obstetrics departments in Lu'an City from 2016 to 2021 were selected, categorized and counted by name, gender, weight, preterm delivery, hepatitis B vaccine（HepB） timely vaccination, vaccination dose, etc. The concentrations of HBsAg and hepatitis B surface antibody (HBsAb) were quantified by magnetic particulate chemiluminescence, and the antibody positivity rate and geometric mean concentration (GMC) of antibodies were analyzed and compared.Results　A total of 172 low birth weight infants were included in this study, of which 121 completed blood sample collection, with a mean age of (3.7±1.7) years, a median weight of 2.30 kg, a proportion of 58.68% of preterm infants, a proportion of 75.21% of infants who received the first dose of HepB timely The number of subjects who completed HepB primary and booster immunizations were 117 and 4, respectively, and the prevalence of HBV infection was 5.79%. Among the uninfected subjects, there was a statistically significant difference between HBsAb GMC of the booster immunization group and the primary immunization group, with Z=-2.17, P=0.030. Among the uninfected and primarily vaccinated subjects,timely vaccination preterm delivery, and birth weight diden´t effect GMC. Among the HBsAb positive subjects, no statistically significant difference in the positivity rate was seen in the primary immunization group compared to the booster immunization group (χ²=2.45, P=0.118); but there was a statistically significant difference between the two groups in GMC (Z=-2.25, P=0.024). In primarily vaccinated and uninfected subjects, there was an overall trend of decreasing HBsAb positivity and GMC after vaccination.Conclusion　In Lu'an, the HBV infection rate of low birth weight infants born to HBsAg-positive mothers is high, the HepB vaccination rate is low, and the total levels of HBsAg and HBsAb are low, so it is necessary to strengthen the implementation of 0-1-2-7 months HepB immunization program for low birth weight infants.