title: Surveillance of influenza A H1N1 2009 among school children during 2009 and 2010 in São Paulo, Brazil.
abstract: BACKGROUND
  Influenza A H1N1 2009 is associated with a high morbidity rate among children around the world, including Brazil. This survey was conducted on samples of symptomatic children (< 12 years) to investigate the influenza virus as the etiological agent of respiratory infections in a day care school in a health facility during the first and second pandemic wave of H1N1 (2009-2010) in São Paulo, Brazil.
  
  
  METHODS
  Influenza infections were determined by real-time PCR in 34% (47/137) of children with a median age of 5 years (8 months - 12 years), from June to October 2009 and in 16% (14/85) of those with median age of 6 years (1-12 years), from March to November 2010.
  
  
  RESULTS
  In general, most positive cases (64%) occurred in children aged 5-12 years, this age group was significantly the most affected (39.8%, p = 0.001, OR = 8.3, CI 95% 1.9-36.9). Wheezing was reported by 31% (19/61) and dyspnea by 23% (14/61) of the studied patients. An outbreak of influenza H1N1 with an attack rate of 35.7% among children (median age 6 years) was documented in April 2010, before the vaccination campaign against the pandemic virus was extended for children up to 5 years in Brazil.
  
  
  CONCLUSIONS
  Therefore, the study reinforces the recommendation to immunize school children to reduce the incidence of the disease.
authors.affiliation: Laboratório de Virologia Clínica, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, SP.
authors.forename: Sandra Baltazar
authors.initials: SB
authors.lastname: Guatura
authors.forename: Aripuana Sakurada Aranha
authors.initials: AS
authors.lastname: Watanabe
authors.forename: Clarice Neves
authors.initials: CN
authors.lastname: Camargo
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Passos
authors.forename: Sheila Negrini
authors.initials: SN
authors.lastname: Parmezan
authors.forename: Tatiane Karen Cabeça
authors.initials: TK
authors.lastname: Tomazella
authors.forename: Emerson
authors.initials: E
authors.lastname: Carraro
authors.forename: Janete
authors.initials: J
authors.lastname: Kamikawa
authors.forename: Celso
authors.initials: C
authors.lastname: Granato
authors.forename: Nancy
authors.initials: N
authors.lastname: Bellei
mesh_terms: D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D058873:Pandemics; D060888:Real-Time Polymerase Chain Reaction; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000209:etiology; D012574:Schools; D018571:Sentinel Surveillance