title: Seroprevalence of antibodies to influenza A/H1N1/2009 among transmission risk groups after the second wave in Mexico, by a virus-free ELISA method.
abstract: OBJECTIVE
  No serological studies have been performed in Mexico to assess the seroprevalence of influenza A/H1N1/2009 in groups of people according to the potential risk of transmission. The aim of this study was to determine the seroprevalence of antibodies against influenza A/H1N1/2009 in subjects in Mexico grouped by risk of transmission.
  
  
  METHODS
  Two thousand two hundred and twenty-two subjects were categorized into one of five occupation groups according to the potential risk of transmission: (1) students, (2) teachers, (3) healthcare workers, (4) institutional home residents aged >60 years, and (5) general population. Seroprevalence by potential transmission group and by age grouped into decades was determined by a virus-free ELISA method based on the recombinant receptor-binding domain of the hemagglutinin of influenza A/H1N1/2009 virus as antigen (85% sensitivity; 95% specificity). The Wilson score, Chi-square test, and logistic regression models were used for the statistical analyses.
  
  
  RESULTS
  Seroprevalence for students was 47.3%, for teachers was 33.9%, for older adults was 36.5%, and for the general population was 33.0%, however it was only 24.6% for healthcare workers (p=0.011). Of the students, 56.6% of those at middle school, 56.4% of those at high school, 52.7% of those at elementary school, and 31.1% of college students showed positive antibodies (p<0.001). Seroprevalence was 44.6% for college teachers, 31.6% for middle school teachers, and 29.8% for elementary school teachers, but was only 20.3% for high school teachers (p=0.002).
  
  
  CONCLUSIONS
  The student group was the group most affected by influenza A/H1N1/2009, while the healthcare worker group showed the lowest prevalence. Students represent a key target for preventive measures.
authors.affiliation: School of Medicine, Instituto Tecnológico y de Estudios Superiores de Monterrey, Av. Morones Prieto 3000 Pte. Col. Los Doctores, CP 64710, Monterrey, Nuevo León, Mexico. lelizond@itesm.mx
authors.forename: Leticia
authors.initials: L
authors.lastname: Elizondo-Montemayor
authors.forename: Mario M
authors.initials: MM
authors.lastname: Alvarez
authors.forename: Martín
authors.initials: M
authors.lastname: Hernández-Torre
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Ugalde-Casas
authors.forename: Lorena
authors.initials: L
authors.lastname: Lam-Franco
authors.forename: Humberto
authors.initials: H
authors.lastname: Bustamante-Careaga
authors.forename: Fernando
authors.initials: F
authors.lastname: Castilleja-Leal
authors.forename: Julio
authors.initials: J
authors.lastname: Contreras-Castillo
authors.forename: Héctor
authors.initials: H
authors.lastname: Moreno-Sánchez
authors.forename: Daniela
authors.initials: D
authors.lastname: Tamargo-Barrera
authors.forename: Felipe
authors.initials: F
authors.lastname: López-Pacheco
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Freiden
authors.forename: Stacey
authors.initials: S
authors.lastname: Schultz-Cherry
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood*; D000956:Antigens, Viral; D002648:Child; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005178:Faculty / Q000706:statistics & numerical data; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control / Q000635:transmission; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies; D013334:Students / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral