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Influenza Virus Infection in Infants Less Than Three Months of Age

Bender, Jeffrey M. MD*; Ampofo, Krow MD*; Gesteland, Per MD, MSc; Sheng, Xiaoming PhD*; Korgenski, Kent MS; Raines, Bill; Daly, Judy A. PhD; Valentine, Karen MS; Srivastava, Rajendu MD, FRCP(C), MPH; Pavia, Andrew T. MD*; Byington, Carrie L. MD*

The Pediatric Infectious Disease Journal: January 2010 - Volume 29 - Issue 1 - p 6-9
doi: 10.1097/INF.0b013e3181b4b950
Original Studies

Objective: We evaluated the presentation, outcomes, and the risk of serious bacterial infection (SBI) in infants <3 months old with influenza virus infection.

Patients and 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.


From the *Divisions of Pediatric Infectious Disease and †Inpatient Pediatrics, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah; and ‡Department of Pediatrics, Pediatric Specialty Clinical Program, Intermountain Healthcare, Salt Lake City, Utah.

Accepted for publication June 25, 2009.

J.M.B. is the recipient of a NIH Rocky Mountain Regional Center for Excellence in Biodefense and Emerging Diseases young investigator award U54 AI065357. P.G. and C.L.B. are supported in part through the CDC-funded Center of Excellence in Public Health Informatics (CDC 1 PO1 CD000284) at the University of Utah. R.S. is the recipient of a NIH/Eunice Kennedy Shriver NICHD career development award K23 HD052553. C.L.B. is further supported by grants from the Public Health Services research grant UL1-RR025764 from the National Center for Research Resources (NIH/NIAID 1 U01 AI074419 and U01-A1061611), and the NIH/Eunice Kennedy Shriver NICHD K24- HD047249. This project was in addition supported by the Children's Health Research Center at the University of Utah.

Address for correspondence: Jeffrey M. Bender, MD, University of Utah School of Medicine, Department of Pediatrics, Division of Pediatric Infectious Diseases, PO Box 581289, Salt Lake City, UT. E-mail:

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© 2010 Lippincott Williams & Wilkins, Inc.