ARCHIVED - Canadian Children Hospitalized for Influenza at Immunization Monitoring Program Active (Impact) Centres, 2003-4


Category: Viral Vaccines or Infections

Moore DL, Vaudry W, Scheifele D, Halperin SA, Déry P, Ford-Jones E, Law B, Lebel M, LeSaux N, Tam T


Although influenza causes serious illness in young children, previous recommendations for immunization targeted children with specific chronic conditions. Our objectives were to (i) determine characteristics of children hospitalized for influenza and their disease manifestations, (ii) obtain baseline data prior to implementation of new recommendations for routine immunization of young children and their caretakers against influenza.


All children hospitalized with laboratory-confirmed influenza at nine Canadian IMPACT tertiary care hospitals during the 2003- 2004 influenza season were identified from virology laboratory results and their charts reviewed.


Five hundred children were admitted because of influenza (495 influenza A, five influenza B). Fifty-seven percent were < 2 years old. Previously healthy children accounted for 53% of all cases (65% of those < 2 years old; only 15% of those> 5 years old). Cases occurred between September and June, with peak activity in November in Edmonton andWinnipeg and from December to February elsewhere. Mean duration of hospitalization was 5.2 days. Twelve percent of children required intensive care unit admission and 6% required mechanical ventilation. Serious complications included myocarditis (two), encephalopathy (four) and meningitis (one). There were three influenza-related deaths. Secondary bacterial infections were identified or suspected in 23% of cases. Antibiotic therapy was administered to 78% of cases while only 7% received anti-influenza drugs.

Information on immunization was available for 82 of 150 children identified as vaccine candidates. Twenty-two had been immunized. The most frequent reasons for failure to immunize were parents: lack of awareness of the indication and infection occurring too early in the season. Only nine children were documentated to have been fully immunized > 14 days before onset of illness.


Health young children and children with underlying illnesses are at risk of hospitalization for influenza. Ongoing surveillance is needed to evaluate the impact of the new immunization recommendations on the burden of influenza illness in children.

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