title: Modeling the long-term antibody response of a hepatitis E vaccine.
abstract: BACKGROUND
  The first commercialized hepatitis E vaccine, HEV 239, has been shown to be safe and highly immunogenic, the protection as well as the vaccine-induced anti-HEV maintained for at least 4.5 years. However, the longer term persistence of the vaccine-induced anti-HEV responses is unknown.
  
  
  METHODS
  Two statistical models, the power-law model and the modified power-law model, were applied to predict the long-term antibody response of the HEV 239 vaccine. The models were fit using the anti-HEV IgG data from a modeling subpopulation of 1278 baseline seronegative vaccinees who seroconverted within one month after finishing the whole vaccination course in the phase 3 trial of HEV 239. In addition, antibody data from a validation subpopulation were used to validate the robustness of the derived models.
  
  
  RESULTS
  In the vaccinees without pre-vaccination immunity, the power-law model and the modified power-law model estimated that the median duration of the detectable antibody (≥0.077 WU/ml) was 8 years and 13 years, respectively. The power-law model and the modified power-law model estimated that 50% of these vaccinees will maintain detectable levels of anti-HEV IgG for 8 years and >30 years, respectively.
  
  
  CONCLUSIONS
  The recombinant hepatitis E vaccine HEV 239 is predicted to provide from 8 years to nearly life-long persistence of anti-HEV IgG above detectable levels. Model predictions are based on conservative mathematical assumptions. (NCT01014845).
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen 361102, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Chen
authors.affiliation: Key Laboratory of Health Technology Assessment of Fujian Province University, School of Public Health, Xiamen University, Xiamen 361102, China.
authors.forename: Zi
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen 361102, China.
authors.forename: Fei-Xue
authors.initials: FX
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen 361102, China.
authors.forename: Shou-Jie
authors.initials: SJ
authors.lastname: Huang
authors.affiliation: School of Mathematical Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Tan
authors.affiliation: Key Laboratory of Health Technology Assessment of Fujian Province University, School of Public Health, Xiamen University, Xiamen 361102, China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, Jiangsu Province, China.
authors.forename: Feng-Cai
authors.initials: FC
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen 361102, China. Electronic address: wuting@xmu.edu.cn.
authors.forename: Ting
authors.initials: T
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen 361102, China. Electronic address: zhangj@xmu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen 361102, China.
authors.forename: Ning-Shao
authors.initials: NS
authors.lastname: Xia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000917:Antibody Formation; D005500:Follow-Up Studies; D006508:Hepatitis Antibodies / Q000097:blood*; D016751:Hepatitis E / Q000517:prevention & control*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008875:Middle Aged; D015233:Models, Statistical; D013997:Time Factors; D016896:Treatment Outcome; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology*; D014761:Viral Hepatitis Vaccines / Q000008:administration & dosage / Q000276:immunology*; D055815:Young Adult
chemical_list: D006508:Hepatitis Antibodies; D007074:Immunoglobulin G; D014614:Vaccines, Synthetic; D014761:Viral Hepatitis Vaccines; C577000:hecolin
keywords: Antibody persistence; Hepatitis E vaccine; Immunogenicity; Mathematical models