Xu H, Zuo H, Zhuang G
Department of Epidemiology, Xi' an Medical University.
Zhonghua Yu Fang Yi Xue Za Zhi. 1998 Jul;32(4):205-7.
To observe the effectiveness of hepatitis B vaccine nine years after primary immunization.
A randomized, controlled and double-blinded trial was designed with 126 children primarily immunized with local produced plasma-derived hepatitis B vaccine nine years ago and 135 placebo-control children aged five to nine years. All the children were followed-up, their blood samples collected and their disease occurrence examined. Their hepatitis B surface antigen (HBsAg), antibody against hepatitis B core antigen (anti-HBc) and antibody against hepatitis B surface antigen (anti-HBs) were tested. Causes of lowering in their antibodies were analyzed with multivariate methods.
During the nine-year follow-up, 4% to 19% of the study subjects dropped out. In the ninth year after immunization (T108), anti-HBs positive rate in the vaccinees and their geometric mean titer (GMT) (65.3% and 5.47, respectively) were still significantly higher than those in the placebo-controls (28.3% and 1.46, respectively), but significantly lower than those in the 6th year after immunization (T72). Multivariate analysis for the causes of lowering in the antibody during the 4th, 6th and 9th year after immunization showed that antibody titer in the vaccines first year after immunization (T12) was a crucial factor for the persistence of the antibody, and natural booster might also played a certain role in it. In the T108, one clinical case of hepatitis B occurred in the placebo control group, but no cases in the vaccinees found, with a protection rate of 81.4% from HBV infection and 84.6% from HBsAg positive-coversion, similar to those in the T72.
The effectiveness of HB vaccine still existed nine years after primary immunization, and no booster dose was needed so far.
观察初次免疫九年后乙肝疫苗的效果。
设计一项随机、对照、双盲试验，选取九年前初次接种当地生产的血浆源性乙肝疫苗的126名儿童以及135名5至9岁的安慰剂对照儿童。对所有儿童进行随访，采集血样并检查疾病发生情况。检测他们的乙肝表面抗原（HBsAg）、乙肝核心抗体（抗-HBc）和乙肝表面抗体（抗-HBs）。采用多变量方法分析抗体水平下降的原因。
在九年的随访期间，4%至19%的研究对象退出。免疫后第九年（T108），疫苗接种组的抗-HBs阳性率及其几何平均滴度（GMT）（分别为65.3%和5.47）仍显著高于安慰剂对照组（分别为28.3%和1.46），但显著低于免疫后第六年（T72）。对免疫后第4年、第6年和第9年抗体水平下降原因的多变量分析表明，免疫后第一年（T12）疫苗接种者的抗体滴度是抗体持续存在的关键因素，自然加强免疫可能也起到了一定作用。在T108时，安慰剂对照组发生1例临床乙肝病例，疫苗接种组未发现病例，对HBV感染的保护率为81.4%，对HBsAg血清学转换的保护率为84.6%，与T72时相似。
初次免疫九年后乙肝疫苗仍有效果，目前无需加强接种。
