title: Change in hepatitis A epidemiology after vaccinating high risk children in Taiwan, 1995-2008.
abstract: Taiwan started to immunize children in 30 indigenous townships against hepatitis A since June 1995. The program was further expanded to 19 non-indigenous townships with higher incidence or increased risk of epidemic in 1997-2002, covering 2% of total population. Annual incidence of hepatitis A decreased from 2.96 in 1995 (baseline period) to 0.90/100,000 in 2003-2008 (vaccination period). The incidence in vaccinated townships and unvaccinated townships declined 98.3% (49.66-0.86/100,000) and 52.6% (1.90-0.90/100,000). In 2003-2008, incidence doubled in people aged >=30 years, mostly in unvaccinated townships (0.42-0.92). During 2003-2008, travel to endemic countries was the most commonly reported risk factor (13.5%). First dose vaccine coverage was 78.8% in 1994-2005 birth cohort. Taiwan's experience demonstrates the great, long-term efficacy of hepatitis A vaccine in disease control in vaccinated townships, and out-of-cohort effect in unvaccinated townships. Further reduction can be achieved by improving vaccination coverage of adults at risk.
authors.affiliation: Field Epidemiology Training Program, Centers For Disease Control, Department of Health, 2F, No. 6 Linsen South Road, Taipei City 100, Taiwan. tsungpei@cdc.gov.tw
authors.forename: Tsung-Pei
authors.initials: TP
authors.lastname: Tsou
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Liu
authors.forename: Ji-Jia
authors.initials: JJ
authors.lastname: Huang
authors.forename: Kun-Ju
authors.initials: KJ
authors.lastname: Tsai
authors.forename: Hsiu-Fang
authors.initials: HF
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology* / Q000517:prevention & control; D022362:Hepatitis A Vaccines / Q000008:administration & dosage*; D006801:Humans; D032521:Immunity, Herd; D017589:Immunization Programs; D015994:Incidence; D007223:Infant; D008297:Male; D011159:Population Surveillance; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult
chemical_list: D022362:Hepatitis A Vaccines