title: Impact of the single-dose immunization strategy against hepatitis A in Argentina.
abstract: BACKGROUND
  After a country wide outbreak occurred during 2003-2004, 1 dose of hepatitis A vaccine was introduced into Argentinian regular immunization schedule for all children aged 12 months in June 2005. The aim of this study was to assess the impact of this novel intervention.
  
  
  METHODS
  A longitudinal analysis was done of hepatitis A virus (HAV) infection rates reported to the National Epidemiological Surveillance System from 2000 to 2011. Occurrence of fulminant hepatic failure (FHF) and liver transplantation cases up to 2011 were also assessed. Incidence rates and clinical impact were compared between pre- and postvaccination periods (2000-2002 vs. 2006-2011). Notification rates were also compared by age groups and geographical regions.
  
  
  RESULTS
  Since 2006, an abrupt decline was observed in HAV infection rates, as well as in FHF and liver transplantation cases. The mean incidence rate of 7.9/100,000 in the postvaccination period represents a reduction of 88.1% (P < 0.001) when compared with the prevaccination period. Neither FHF nor liver transplantation due to HAV infection were observed since March 2007. Decline in incidence rates was evident in all geographical regions and all age groups but was higher in the prevaccination most affected areas and in young children. Although an absolute decrease was observed for cases and rates in all age groups, since 2006, a higher proportion of cases was observed in people >14 years of age.
  
  
  CONCLUSIONS
  The single-dose vaccination strategy has been highly effective for controlling HAV infection in all age groups till now in Argentina. Long-term surveillance will be critical to document the sustained success of this unique intervention.
authors.affiliation: From the *Ministerio de Salud de la Nación, Av. de 9 de Julio 1925 (C1073ABA); †INEI-ANLIS "Dr. Carlos Malbrán", Av. Vélez Sarsfield 563 (1281); and ‡Sociedad Argentina de Pediatría, C.A.B.A., Argentina.
authors.forename: Carla
authors.initials: C
authors.lastname: Vizzotti
authors.forename: Jorge
authors.initials: J
authors.lastname: González
authors.forename: Angela
authors.initials: A
authors.lastname: Gentile
authors.forename: Analía
authors.initials: A
authors.lastname: Rearte
authors.forename: Margarita
authors.initials: M
authors.lastname: Ramonet
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Cañero-Velasco
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Pérez Carrega
authors.forename: Analía
authors.initials: A
authors.lastname: Urueña
authors.forename: Máximo
authors.initials: M
authors.lastname: Diosque
mesh_terms: D000293:Adolescent; D000328:Adult; D001118:Argentina / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006506:Hepatitis A / Q000453:epidemiology* / Q000517:prevention & control*; D022362:Hepatitis A Vaccines / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D007223:Infant; D008137:Longitudinal Studies; D008875:Middle Aged; D055815:Young Adult
chemical_list: D022362:Hepatitis A Vaccines