title: Effect of age on the incidence of acute hepatitis B after 25 years of a universal newborn hepatitis B immunization program in Taiwan.
abstract: BACKGROUND
  Raising concerns about the waning immunity of cohorts receiving hepatitis B virus (HBV) vaccination in infancy persuaded us to identify the changing incidence of acute hepatitis B (AHB) in children and young adults.
  
  
  METHODS
  Data on AHB surveillance through the National Notifiable Disease Surveillance System from July 2001 to June 2009 were collected and described. Cases were divided into 2 cohorts according to their birth year: before or after the universal newborn HBV vaccination program. Age-specific incidence was compared for the 2 birth cohorts with diagnosis at age 15-24 years.
  
  
  RESULTS
  In total, 2226 patients with AHB were identified. AHB rates varied by age; the highest rates occurred among unvaccinated individuals aged 25-39 years (2.33/100 000). Due to breakthrough HBV infection from mother-to-infant transmission, vaccinated infants (0.78/100 000) had higher rates than those aged 1-14 years (0.04/100 000), who had the lowest rates. The incidence in vaccinated birth cohorts was significantly lower than in unvaccinated birth cohorts among patients 15-24 years old, with an adjusted-relative risk of 0.42.
  
  
  CONCLUSIONS
  Implementation of universal-at-birth HBV immunization programs has effectively reduced the occurrence of AHB among adolescents and young adults in Taiwan for >25 years, making infants and the 25-39-year-old cohort additional targets for preventing AHB.
authors.affiliation: Centers for Disease Control, Department of Health, Taipei, Taiwan.
authors.forename: Wei-Ju
authors.initials: WJ
authors.lastname: Su
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Liu
authors.forename: Ding-Ping
authors.initials: DP
authors.lastname: Liu
authors.forename: Shu-Fong
authors.initials: SF
authors.lastname: Chen
authors.forename: Ji-Jia
authors.initials: JJ
authors.lastname: Huang
authors.forename: Ta-Chien
authors.initials: TC
authors.lastname: Chan
authors.forename: Mei-Hwei
authors.initials: MH
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D006509:Hepatitis B / Q000453:epidemiology* / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D016012:Poisson Distribution; D011159:Population Surveillance; D013624:Taiwan / Q000453:epidemiology; D014611:Vaccination; D055815:Young Adult