title: Pandemic influenza A/H1N1 2009 antibodies in the metropolitan area of Buenos Aires in Argentina.
abstract: OBJECTIVE
  To estimate the infection prevalence in Buenos Aires during the outbreak of pandemic influenza A/H1N1 2009 virus (A(H1N1)pdm09).
  
  
  METHODS
  A(H1N1)pdm09-specific antibodies were measured by hemagglutination inhibition assay in human serum samples collected 6 months after the outbreak and before the introduction of the A(H1N1)pdm09 vaccine in Argentina. Baseline levels of cross-reactive antibodies to A(H1N1)pdm09 were determined by testing 162 serum samples collected before 2009.
  
  
  RESULTS
  The overall seroprevalence of A(H1N1)pdm09 in 150 children and 427 adults was 28.9% (95% confidence interval (CI) 25-33%), with a 58.0% prevalence in children <19 years of age and an 18.7% prevalence in adults ≥19 years of age (p<0.001). The prevalence was 43.5% in children <5 years old and 60.6% among children aged 5-18 years. The prevalence in adults declined with increasing age: 24.9% in 19-39-year-olds, 9.7% in 40-59-year-olds, and 8.1% in those ≥60 years old. The prevalence of specific A(H1N1)pdm09 antibodies was higher compared with the baseline in children (p=0.014), adolescents (p<0.001), and adults <40 years old (p=0.017). Seroprevalence in health care workers was not different from the rest of the population (13.6% vs. 19.3%, respectively; p=0.421).
  
  
  CONCLUSIONS
  The prevalence of specific A(H1N1)pdm09 antibodies was high at 28.9%. The highest prevalence was observed in children, adolescents, and young adults.
authors.affiliation: Hospital de Clínicas "José de San Martín", Universidad de Buenos Aires, Arenales 2557, 1° A (CP 1425), Buenos Aires, Argentina.
authors.forename: Mariana I
authors.initials: MI
authors.lastname: Labato
authors.affiliation: Hospital de Niños "Ricardo Gutiérrez", Buenos Aires, Argentina.
authors.forename: María M
authors.initials: MM
authors.lastname: Contrini
authors.affiliation: Hospital de Niños "Ricardo Gutiérrez", Buenos Aires, Argentina.
authors.forename: Daniela
authors.initials: D
authors.lastname: Lazzarini
authors.affiliation: Servicio de Virus Respiratorios, Instituto Nacional de Enfermedades Infecciosas -Administración Nacional de Laboratorios e Institutos de Salud "Dr. Carlos Malbrán", Buenos Aires, Argentina.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Campos
authors.affiliation: Hospital de Clínicas "José de San Martín", Universidad de Buenos Aires, Arenales 2557, 1° A (CP 1425), Buenos Aires, Argentina.
authors.forename: María L
authors.initials: ML
authors.lastname: Gauna
authors.affiliation: Hospital de Clínicas "José de San Martín", Universidad de Buenos Aires, Arenales 2557, 1° A (CP 1425), Buenos Aires, Argentina.
authors.forename: Ronald
authors.initials: R
authors.lastname: Claros
authors.affiliation: Hospital de Niños "Ricardo Gutiérrez", Buenos Aires, Argentina.
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: López
authors.affiliation: Servicio de Virus Respiratorios, Instituto Nacional de Enfermedades Infecciosas -Administración Nacional de Laboratorios e Institutos de Salud "Dr. Carlos Malbrán", Buenos Aires, Argentina.
authors.forename: Vilma L
authors.initials: VL
authors.lastname: Savy
authors.affiliation: Hospital de Clínicas "José de San Martín", Universidad de Buenos Aires, Arenales 2557, 1° A (CP 1425), Buenos Aires, Argentina. Electronic address: dr.cm.luna@gmail.com.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Luna
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood*; D000918:Antibody Specificity; D001118:Argentina / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006761:Hospitals; D006801:Humans; D015994:Incidence; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D016036:Seroepidemiologic Studies; D011795:Surveys and Questionnaires; D014505:Urban Population; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral
keywords: H1N1 subtype; Influenza A virus; Prevalence; Seroepidemiological study