title: Viral shedding in children infected by pandemic A/H1N1/2009 influenza virus.
abstract: BACKGROUND
  The aim of this study was to investigate viral shedding in otherwise healthy children with pandemic A/H1N1/2009 influenza in order to define how long children with pandemic A/H1N1/2009 influenza shed the virus, and also plan adequate measures to control the spread of the disease within households.
  
  
  RESULTS
  In 74 otherwise healthy children with pandemic A/H1N1/2009 influenza, nasopharyngeal swabs were taken for virus detection upon hospital admission and every two days until negative. The nasopharyngeal swabs of all of the children were positive for pandemic A/H1N1/2009 influenza virus in the first three days after the onset of infection, and only 21.6% and 13.5% remained positive after respectively 11 and 15 days. No child was positive after more than 15 days. Viral load also decreased over time, and was not associated with patient age or the risk of pneumonia. Those who shed the virus for ≥ 9 days were not at any increased risk of suffering from more severe disease in comparison with those who shed the virus for a shorter time, but their households experienced a significantly higher number of influenza-like illness during the two weeks after the onset of the initial disease (72.3% vs 41.4%; p < 0.05).
  
  
  CONCLUSIONS
  Regardless of their age, healthy children can shed pandemic A/H1N1/2009 influenza virus for up to two weeks after illness onset, and the households of the children who shed the virus for ≥ 9 days suffered a higher number of influenza-like illness in the two weeks following the onset of the first disease. This could suggest that when a completely unknown influenza virus is circulating, isolation period of infected children has to be longer than the 7 days recommended for the infections due to seasonal influenza viruses.
authors.affiliation: Department of Maternal and Pediatric Sciences, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Esposito
authors.forename: Cristina
authors.initials: C
authors.lastname: Daleno
authors.forename: Fausto
authors.initials: F
authors.lastname: Baldanti
authors.forename: Alessia
authors.initials: A
authors.lastname: Scala
authors.forename: Giulia
authors.initials: G
authors.lastname: Campanini
authors.forename: Francesca
authors.initials: F
authors.lastname: Taroni
authors.forename: Emilio
authors.initials: E
authors.lastname: Fossali
authors.forename: Claudio
authors.initials: C
authors.lastname: Pelucchi
authors.forename: Nicola
authors.initials: N
authors.lastname: Principi
mesh_terms: D002648:Child; D002675:Child, Preschool; D006801:Humans; D017053:Infection Control / Q000379:methods; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000517:prevention & control / Q000821:virology*; D008137:Longitudinal Studies; D009305:Nasopharynx / Q000821:virology; D013997:Time Factors; D019562:Viral Load; D017201:Virus Shedding