title: Waning of anti-HAV immunity in Shijiazhuang prefecture, Hebei province, China: a comparison of seroprevalence between 1992 and 2011.
abstract: OBJECTIVE
  To study the epidemiological patterns of hepatitis A, and immunity of entire population in Shijiazhuang prefecture, Hebei province, a former hyper-endemic area in north China.
  
  
  METHODS
  Cross-sectional, seroprevalence surveys with two-stage cluster sampling were conducted among population older than 2-year between 1992 and 2011. During the 2011 serological survey, blood samples from infants <18 months without hepatitis A immunization history were also collected to determine maternal anti-HAV antibody. Serum samples were tested for anti-HAV antibody by domestic reagent or Abbott reagent. Viral hepatitis incidence rates and gross domestic product data were derived from local governmental statistics.
  
  
  RESULTS
  Concomitant with the reduction of reported hepatitis A cases between 1992 and 1996 was a significant decline of HAV infections. The average prevalence decreased from 93.6% to 41.9%, and the average age at new infection was postponed from infancy to adolescence. This was attributed to improved socio-economic conditions. With intensive vaccination, a return of new seroconversion rate and seroprevalence was observed. A well fitted exponential regression equation (R(2)=0.96, p<0.0001) modeled that the maternal antibody would wane to <20 mIU/mL at 13 months.
  
  
  CONCLUSIONS
  Benefiting from the booming economy, rapid improvement in sanitation, safe water supply, and implementation of hepatitis A vaccines, the epidemiological pattern of hepatitis A moved from high to intermediate endemicity in Shijiazhuang. Policy makers should be aware of the waning of immunity in entire population, and adapt immunization strategy timely, to ensure a lifelong protection against hepatitis A virus.
authors.affiliation: Key Laboratory of Medical Molecular Virology of MoE & MoH, and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Zhengding County Center for Disease Control and Prevention, Zhengding 050800, People's Republic of China.
authors.forename: Xin-Jiang
authors.initials: XJ
authors.lastname: Zhang
authors.affiliation: Hebei Province Center for Disease Control and Prevention, Shijiazhuang 050800, People's Republic of China.
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Zhao
authors.affiliation: Zhengding County Center for Disease Control and Prevention, Zhengding 050800, People's Republic of China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zhang
authors.affiliation: Fudan University, Shanghai 200032, People's Republic of China.
authors.forename: Song-Mei
authors.initials: SM
authors.lastname: Wang
authors.affiliation: Zhengding County Center for Disease Control and Prevention, Zhengding 050800, People's Republic of China.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Hao
authors.affiliation: Zhengding County Center for Disease Control and Prevention, Zhengding 050800, People's Republic of China.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Zhang
authors.affiliation: Hebei Province Center for Disease Control and Prevention, Shijiazhuang 050800, People's Republic of China.
authors.forename: Jing-Chen
authors.initials: JC
authors.lastname: Ma
authors.affiliation: Department of Mathematics, Mathematics and Science College, Shanghai Normal University, Shanghai 200234, People's Republic of China. Electronic address: fanyun0919@shnu.edu.cn.
authors.forename: Yun
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Key Laboratory of Medical Molecular Virology of MoE & MoH, and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China. Electronic address: xywang@shmu.edu.cn.
authors.forename: Xuan-Yi
authors.initials: XY
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology*; D035922:Hepatitis A Antibodies / Q000097:blood*; D006801:Humans; D007112:Immunity, Maternally-Acquired; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016036:Seroepidemiologic Studies; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies
keywords: Anti-HAV; China; Hepatitis A virus; Immunization; Maternal; Seroprevalence