title: Single-Dose Universal Hepatitis A Immunization in Argentina: Low Viral Circulation and High Persistence of Protective Antibodies Up to 4 Years.
abstract: BACKGROUND
  Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children aged 12 months in 2005. Between 2005 and 2011, a dramatic decline was observed in HAV infection rates, fulminant hepatitis, and liver transplantation. This study assessed current viral circulation and estimated protective antibody persistence 4 years after vaccination.
  
  
  METHODS
  Prevalence of prevaccination anti-HAV antibodies in 12-month-old children was evaluated as an indirect estimation of viral circulation (Group A). Seroprevalence was also measured in 5-year-old children who received 1 dose of HAV vaccine at 1 year of age (Group B). Blood samples were tested for immunoglobulin (Ig)G anti-HAV antibodies (seroprotection = ≥10 mIU/mL). All Group A-positive samples were tested for IgM anti-HAV antibodies to identify recent infections. Logistic regression analysis was done to evaluate associations between demographic and socioeconomic variables and seroprotection.
  
  
  RESULTS
  Of 433 children from Group A, 29.5% (95% confidence interval [CI], 25.2-33.8) were positive for IgG anti-HAV antibodies with a geometric mean concentration (GMC) of 6.17 mIU/mL (95% CI, 5.33-7.15 mIU/mL); all IgM anti-HAV were negative. From 1139 in Group B, 93% (95% CI, 91.7-94.6) maintained seroprotection with a GMC of 97.96 mIU/mL (95% CI, 89.21-107.57 mIU/mL). Kindergarten attendance was associated with seroprotection in Group B (odds ratio [OR], 2.0; 95% CI, 1.26-3.3). In contrast, high maternal educational level was associated with a lack of seroprotection in this group (OR, .26; 95% CI, .09-.8).
  
  
  CONCLUSIONS
  Single-dose, universal hepatitis A immunization in infants resulted in low HAV circulation and persistent immunologic protection up to 4 years in Argentina. Variables associated with presence or absence of seroprotection in vaccinated children could be related to differences in hygiene habits in settings with residual viral circulation.
authors.affiliation: Ministerio de Salud de la Nación, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: C
authors.initials: C
authors.lastname: Vizzotti
authors.affiliation: Instituto Nacional de Enfermedades Infecciosas - Administración Nacional de Laboratorios e Instituto de la Salud "Dr. Carlos Malbrán," Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: J
authors.initials: J
authors.lastname: González
authors.affiliation: Ministerio de Salud de la Nación, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Rearte
authors.affiliation: Ministerio de Salud de la Nación, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Urueña
authors.affiliation: Ministerio de Salud de la Nación, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Pérez Carrega
authors.affiliation: Ministerio de Salud de la Provincia de Tucumán, Programa Ampliado de Inmunizaciones, Argentina.
authors.forename: R
authors.initials: R
authors.lastname: Calli
authors.affiliation: Hospital de Niños Ricardo Gutiérrez, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Gentile
authors.affiliation: Ministerio de Salud de la Provincia de Santa Fe, Programa Ampliado de Inmunizaciones, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Uboldi
authors.affiliation: Hospital Nacional Profesor Dr. Alejandro Posadas, Provincia de Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Ramonet
authors.affiliation: Hospital de Niños de San Justo, Provincia de Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Cañero-Velasco
authors.affiliation: Ministerio de Salud de la Nación, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Diosque
mesh_terms: D001118:Argentina / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology / Q000517:prevention & control*; D035922:Hepatitis A Antibodies / Q000097:blood*; D022362:Hepatitis A Vaccines / Q000627:therapeutic use*; D006801:Humans; D007115:Immunization Schedule; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D008297:Male; D016036:Seroepidemiologic Studies
chemical_list: D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D007074:Immunoglobulin G; D007075:Immunoglobulin M
keywords: Argentina; hepatitis A; immunogenicity; single-dose vaccination; viral circulation