title: Surveillance for seasonal influenza virus prevalence in hospitalized children with lower respiratory tract infection in Guangzhou, China during the post-pandemic era.
abstract: BACKGROUND
  Influenza A(H1N1)pdm09, A(H3N2) and B viruses have co-circulated in the human population since the swine-origin human H1N1 pandemic in 2009. While infections of these subtypes generally cause mild illnesses, lower respiratory tract infection (LRTI) occurs in a portion of children and required hospitalization. The aim of our study was to estimate the prevalence of these three subtypes and compare the clinical manifestations in hospitalized children with LRTI in Guangzhou, China during the post-pandemic period.
  
  
  METHODS
  Children hospitalized with LRTI from January 2010 to December 2012 were tested for influenza A/B virus infection from their throat swab specimens using real-time PCR and the clinical features of the positive cases were analyzed.
  
  
  RESULTS
  Of 3637 hospitalized children, 216 (5.9%) were identified as influenza A or B positive. Infection of influenza virus peaked around March in Guangzhou each year from 2010 to 2012, and there were distinct epidemics of each subtype. Influenza A(H3N2) infection was more frequently detected than A(H1N1)pdm09 and B, overall. The mean age of children with influenza A virus (H1N1/H3N2) infection was younger than those with influenza B (34.4 months/32.5 months versus 45 months old; p<0.005). Co-infections of influenza A/ B with mycoplasma pneumoniae were found in 44/216 (20.3%) children.
  
  
  CONCLUSIONS
  This study contributes the understanding to the prevalence of seasonal influenza viruses in hospitalized children with LRTI in Guangzhou, China during the post pandemic period. High rate of mycoplasma pneumoniae co-infection with influenza viruses might contribute to severe disease in the hospitalized children.
authors: State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: Wen Da
authors: WD
authors: Guan
authors: Department of Pediatric, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: Xiao Yan
authors: XY
authors: Gong
authors: Centre of Influenza Research, School of Public Health, HKU Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; HKU-Pasteur Research Pole, School of Public Health, HKU Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors: Chris Ka Pun
authors: CK
authors: Mok
authors: State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: Ting Ting
authors: TT
authors: Chen
authors: State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: Shi Guan
authors: SG
authors: Wu
authors: State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: Si Hua
authors: SH
authors: Pan
authors: Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong, China.
authors: Benjamin John
authors: BJ
authors: Cowling
authors: State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: Zi Feng
authors: ZF
authors: Yang
authors: State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Department of Pediatric, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors: De Hui
authors: DH
authors: Chen
mesh_terms: D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D006760:Hospitalization; D006801:Humans; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology*; D011159:Population Surveillance; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000150:complications / Q000453:epidemiology*; D012189:Retrospective Studies; D012621:Seasons