Surveillance for Influenza Admissions Among Children Hospitalized in Canadian Immunization Monitoring Program Active Centers, 2003-2004

doi:10.1542/peds.2005-2744

Surveillance for Influenza Admissions Among Children Hospitalized in Canadian Immunization Monitoring Program Active Centers, 2003–2004

Dorothy L. Moore, PhD, MD^a, Wendy Vaudry, MD^b, David W. Scheifele, MD^c, Scott A. Halperin, MD^d, Pierre Déry, MD^e, Elizabeth Ford-Jones, MD^f, Haider M. Arishi, MD^g, Barbara J. Law, MD^g, Marc Lebel, MD^h, Nicole Le Saux, MDⁱ, Karen Grimsrud, MD^j and Theresa Tam, MBBS^k

^a Infectious Diseases Division, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
^b Division of Infectious Diseases, Stollery Children's Hospital, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
^c Division of Infectious Diseases, British Columbia Children's Hospital, Vaccine Evaluation Center, University of British Columbia, Vancouver, British Columbia
^d Department of Pediatrics, Dalhousie University, IWK Health Centre, Halifax, Nova Scotia, Canada
^e Centre Hospitalier Universitaire de Québec, Laval University, Québec, Québec, Canada
^f Division of Infectious Diseases, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
^g Winnipeg Children's Hospital, University of Manitoba, Winnipeg, Manitoba, Canada
^h Department of Pediatrics, Hôpital Ste Justine, University of Montréal, Montréal, Québec, Canada
ⁱ Division of Infectious Diseases, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
^j Provincial Health Office, Alberta Health and Wellness, Edmonton, Alberta, Canada
^k Immunization and Respiratory Infections Division, Centre for Infectious Disease Prevention and Control, Public Health Agency of Canada, Ottawa, Ontario, Canada

OBJECTIVES. Influenza is a common childhood infection that mayresult in hospitalization. Our objectives were to (1) determinecharacteristics of children hospitalized for influenza and diseasemanifestations and (2) obtain baseline data before implementationof new recommendations for routine immunization of young childrenand their caretakers against influenza.

METHODS. All of the children hospitalized with laboratory-confirmedinfluenza at 9 Canadian tertiary care hospitals during the 2003–2004influenza season were identified from virology laboratory reports,and their charts were reviewed.

RESULTS. There were 505 children admitted because of influenza.Fifty-seven percent were <2 years old. Previously healthychildren accounted for 58% of all of the cases. Pulmonary andneurologic disorders were the most common underlying chronicconditions. Fever and cough were the most frequent manifestations.Seizures occurred in 9% of cases. Serious complications includedmyocarditis (2), encephalopathy (6), and meningitis (1). Therewere 3 influenza-related deaths. Mean duration of hospitalizationwas 5.3 days. Twelve percent of children required ICU admission,and 6% required mechanical ventilation. Antibiotic therapy wasadministered in 77% of cases, and 7% received anti-influenzadrugs. Information on influenza vaccination was available for84 of 154 children identified as vaccine candidates. Twentytwo had received vaccine, but only 7 children had been fullyimmunized >14 days before the onset of illness.

CONCLUSIONS. Healthy young children and children with chronicconditions are at risk for serious illness with influenza. Ongoingsurveillance is needed to evaluate the impact of changing immunizationrecommendations on the burden of influenza illness in children.

Key Words: influenza • vaccine • pediatrics

Abbreviations: IMPACT—Immunization Monitoring Program Active • OR—odds ratio • CI—confidence interval

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ARTICLE

Surveillance for Influenza Admissions Among Children Hospitalized in Canadian Immunization Monitoring Program Active Centers, 2003–2004