title: [Persistence of immune memory to hepatitis B vaccine among infants with normal or high antibody response to primary vaccination: a five-year following-up study].
abstract: OBJECTIVE
  To examine the immune memory status to hepatitis B vaccine among infants with normal or high antibody response to primary vaccination, 5 years after the primary vaccination and the risk factors associated with the immune memory.
  
  
  METHODS
  Titers of the antibody against hepatitis B surface antigen (anti-HBs) were detected, five years after the primary vaccination among children who appeared normal or high response to hepatitis B primary vaccination in infancy. Those whose anti-HBs titers were low than protective level (10 mIU/ml) were given a challenge dose of hepatitis B vaccine and titers of anti-HBs were detected 14 days after the challenge. Positive rate and geometric mean titer (GMT) of anti-HBs were calculated. Level of the anti-HBs titers after primary vaccination, at following-up and after the challenge periods were divided into different levels, respectively. Risk factors associated with the levels of anti-HBs titer after the challenge were examined by univariate analysis that and multivariable analysis.
  
  
  RESULTS
  Anti-HBs waned to the level below protective standard among 37.98% of the children with normal or high antibody response to hepatitis B primary vaccination; among those children whose anti-HBs were below the protection standard. The seroconversion rate and GMT of anti-HBs after the challenge dose were 98.95% (757/765) and 2 811.69 mIU/ml [95% Confidence Interval (CI) :2 513.55-3 145.19 mIU/ml] , respectively. Titers and levels of anti-HBs after the challenge, appeared an increase with anti-HBs after primary vaccination and the anti-HBs in the following-up (F=5.46, 10.23 respectively; P<0.000 1 for both) periods. Results from the multivariable analysis showed that gender, premature birth and birth weight were factors insignificantly associated with the anti-HBs titers after the dose of challenge, while the anti-HBs levels were independently associated with the levels of anti-HBs titer after the challenge [OR = 1.001 (95%CI: 1.000-1.002) , P<0.001; OR=1.28 (95%CI: 1.81-1.39) , P<0.001]at the following-up periods.
  
  
  CONCLUSIONS
  Strong immune memory could be found among those children with normal or high responses to hepatitis B vaccination, 5 years after the primary vaccination. The intensity of immune memory might be associated with the anti-HBs titer after primary vaccination as well as the anti-HBs titers before the challenge dose was given.
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China; Email : zl9127@163.com.
authors: Li
authors: L
authors: Zhang
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China.
authors: Bingyu
authors: B
authors: Yan
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China.
authors: Jiaye
authors: J
authors: Liu
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China.
authors: Jingjing
authors: J
authors: Lyu
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China.
authors: Yi
authors: Y
authors: Feng
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China.
authors: Aiqiang
authors: A
authors: Xu
authors: Expanded Program Immunization Division of Shandong Provincial Center for Disease Control and Prevention, Shandong Provincial Key Laboratory of Infectious Disease Control and Prevention, Jinan 250014, China.
authors: Lizhi
authors: L
authors: Song
authors: National Immunization Program, Chinese Center for Disease Control and Prevention.
authors: Xiaofeng
authors: X
authors: Liang
authors: National Immunization Program, Chinese Center for Disease Control and Prevention.
authors: Li
authors: L
authors: Li
authors: National Immunization Program, Chinese Center for Disease Control and Prevention.
authors: Fuqiang
authors: F
authors: Cui
authors: National Immunization Program, Chinese Center for Disease Control and Prevention.
authors: Guomin
authors: G
authors: Zhang
authors: National Immunization Program, Chinese Center for Disease Control and Prevention.
authors: Fuzhen
authors: F
authors: Wang
mesh_terms: D000917:Antibody Formation; D002648:Child; D005500:Follow-Up Studies; D006509:Hepatitis B / Q000517:prevention & control*; D006510:Hepatitis B Antibodies / Q000302:isolation & purification*; D006514:Hepatitis B Surface Antigens / Q000276:immunology; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006801:Humans; D007114:Immunization; D007156:Immunologic Memory; D007223:Infant; D012307:Risk Factors; D000069078:Seroconversion
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines