title: Influenza virus infection in infants less than three months of age.
abstract: OBJECTIVE
  We evaluated the presentation, outcomes, and the risk of serious bacterial infection (SBI) in infants <3 months old with influenza virus infection.
  
  
  METHODS
  We identified demographic, hospitalization, and microbiologic data from computerized medical records for all infants and children <24 months of age, with laboratory confirmed influenza infection cared for at a tertiary care children's hospital during 4 winter seasons (2004-2008). We compared those <3 months of age with older groups.
  
  
  RESULTS
  We identified 833 children <24 months of age with laboratory-confirmed influenza. Of those, 218 were <3 months old. Influenza accounted for 3.6% of all evaluations of febrile infants and 12% of febrile infant encounters during winter. Infants <3 months of age were less likely to have a high risk chronic medical condition, but were more likely to be hospitalized than children 3 to <24 months old (P < 0.005). Infants <3 months with influenza had fewer prolonged hospital stays than those 3 to <6 months old [P = 0.056; OR: 0.5 (0.24-1.0)] and 6 to <12 months old [P = 0.011; OR: 0.43 (0.24-0.83)]. Five (2.3%) infants <3 months old had SBI.
  
  
  CONCLUSIONS
  Infants <3 months of age with influenza virus infection often present with fever alone. Although they are more likely to be hospitalized than those 3 to <24 months old, hospital stays are short and outcomes generally good. Infants with influenza virus infection have a low risk of concomitant SBI.
authors.affiliation: University of Utah School of Medicine, Department of Pediatrics, Division of Pediatric Infectious Diseases, PO Box 581289, Salt Lake City, UT, USA. Jeffrey.Bender@hsc.utah.edu
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Bender
authors.forename: Krow
authors.initials: K
authors.lastname: Ampofo
authors.forename: Per
authors.initials: P
authors.lastname: Gesteland
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Sheng
authors.forename: Kent
authors.initials: K
authors.lastname: Korgenski
authors.forename: Bill
authors.initials: B
authors.lastname: Raines
authors.forename: Judy A
authors.initials: JA
authors.lastname: Daly
authors.forename: Karen
authors.initials: K
authors.lastname: Valentine
authors.forename: Rajendu
authors.initials: R
authors.lastname: Srivastava
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Pavia
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Byington
mesh_terms: D000367:Age Factors; D001419:Bacteria / Q000302:isolation & purification; D001424:Bacterial Infections / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology* / Q000473:pathology*; D007902:Length of Stay; D008297:Male; D009975:Orthomyxoviridae / Q000302:isolation & purification*; D012307:Risk Factors; D016896:Treatment Outcome